Understanding Audiology: Masking and Audiograms PDF

Created with Coconote - https://coconote.app Understanding Audiology: Masking and Audiograms The most simple topic. It's not super hard either. You guys will get your head around it. It's not a beloved topic. It's one that, in audiology, we spend a lot of time on in the 2nd year. It feels very ro...

Created with Coconote - https://coconote.app Understanding Audiology: Masking and Audiograms The most simple topic. It's not super hard either. You guys will get your head around it. It's not a beloved topic. It's one that, in audiology, we spend a lot of time on in the 2nd year. It feels very routine. It's not, you know, it's not super challenging. It's the issue of when you're testing hearing in one ear, how do you isolate that ear? And it becomes an important issue in audiology. We're not gonna go in this class too far down that road because that's not really useful or practical for SLPs. You're not gonna be doing masking in the clinic. Masking in the clinic. The focus of the class will be on understanding why we mask and how to read the audiogram. Like, when you should be reading mask symbols versus unmasked symbols and why it matters. So if you're in order to have competency in reading hearing tests and understanding hearing results, you do need to understand a little bit about masking. So that's the focus of this. It's understanding the why, when we use masked symbols versus unmasked, a little bit of the lingo around it, to develop that basic competency, that really everyone should have. We aren't so if you have bought or found the textbook and read the textbook, the chapter is good. It it goes a little bit it goes into the practice of masking, which is beyond what we're covering. So just know that you're doing the reading. It's, you know, it's not it's it's well written and the practice isn't, you know, that super hard either. It's just not what we're covering in class. So feel free to read it if you're interested. Those on the audiology side, you're gonna get this, you know, you'll get a little bit of this again, but we're gonna go deeper into how you do with different methods, different techniques. You'll get hands on, but not in this class. That's down the road. So yeah, it's not always everyone's favorite because it's it's not super exciting. You're covering up one ear so you can test the other. But it's really important. It's it's kind of one of those core competencies to understand hearing and hearing tests that you really need. And so I don't have a ton of slides today. I'm gonna try not to rush through this, to leave time for questions. If we're done early, that's good. I don't wanna make promises because some yeah. I'd rather cover it fully. I'm planning to be here for up to 6 hours. Do you guys are? Just kidding. 3 hours tops. 3 hours tops. Maybe early. I don't know. I mean, I feel like it's a curse if I say that. It won't be. So I don't wanna make make promises. Someone will get in front of me 1 year for saying like, we're gonna get out early today, and then it was always, you know, 1 minute early. Alright. Let's try not to recreate that. We'll try to be honest. Okay. So a little bit of summary before we get into masking. Because last week, we covered a lot. Who has have you had a chance to be in the lab yet? Have some groups been anyone? No? Okay. This week coming? Okay. Alright. It is pretty straightforward. We covered a lot during the lecture. We finished up with sort of the practicality, which you'll be getting hands on with. You'll be doing training with Madeline on. But just to recap, some of the core important things that you'll want to to learn. A few of these are just memorization, descriptive titles, things like that. Not, you know, not a ton of memorization, but things you just have to know, symbols, which I won't talk about as much today, but I talked about that last week. So so when we're describing a loss and that will be a core piece. So that's gonna be something that you have to do in the case studies, in the tests, and so on. You should be, you know, good at describing a hearing loss. You should be able to look at it and say that's what it is. The things you're going to want to say are one thing that's not on here is ear. What ear are we looking at? It's an easy thing to miss, but that's where x's are left, o's are right, right, and so on. So you want to remember to say ear, if we know which ear. And also to remember, and this will make more sense after the lecture, but just to note it now. Sometimes you're not the symbols will suggest one ear, but you're not sure what ear it's coming from. That's where masking comes in. So that's, if it's something that you really can't know what ear it's from and you write down, oh, that's the left ear, that's wrong. Right? Because knowing that you don't know what ear it's from is important. So you wanna be able to say ear, the degree, what's, you know, how much hearing loss it is. And that's where you have the categories of, the normal or the typical range. Remember that goes down to 25. You can and it's fine if you want to say anything past 15 up to 25 is slight. That's up to you. It varies by clinic, by, by audiologist, by SLP. The if you're doing, kids, we typically do that just as a reminder. We typically will say slight. And then you have mild up to 40, moderate up to 55, moderately severe up to 70, severe up to 90, profound is beyond that. Okay? So you wanna know that those descriptive titles. And that's in last week's lecture. The other things to know that are important, pure tone average, it's always the average of 500, 1,000, 2,000. You'd often say PTA, which also means parent teacher association, but in this context, pure tone average. 512. And there's a reason we choose those frequencies. You sometimes will see other PTAs calculated in research and specific applications. But in the clinic, PTA is 512. 500, 1000, 2000 is what I mean. Percentage hearing loss, we don't use it, but just know the formula. So if someone you know, if you're talking to a physician, if you're talking to someone who's seen a doctor, you understand what that means. Right? And then what goes with degree is that is configuration. So we'll go through some examples today. The different shapes. Right? Because when you're describing a loss you're describing ear, degree and configuration, and then type. And when you're looking at an audiogram, you can say conductive versus sensory neural. You really can't do sensory versus neural. So we typically just write sensory, change the y to an I and say neural. Or you could write sensory slash neural, but we typically just say sensory neural. It's our own word. So conductive versus sensory neural. There are other tests that will help you separate sensory versus neural, later. But with an audiogram, that's what we can do. Okay. You might be talking about, mentioning sort of potential causes what's going on. For instance, we haven't really covered this, but, you know, when you see Carhartt's notch, you suggest that might be Odysseus. But if you see, a 4 k notch, and particularly after a case history, you know, you know, they're a musician. That's likely noise induced hearing loss. Right? So you might be there might be, some other information added on to that. But the core thing is always, ear, degree configuration, and type. So this is a left, conductive hearing loss. It's mild, that's flat. You know, that's clunky but, you know, you're gonna wanna describe those things. Questions? So the core. If one of those things you can't describe, again, like, if you don't know what ear it's coming from, leave that off. Right? Or if you don't know if it's conductive or sensorineural because no one's done bone conduction, don't describe the type. Right? So only describe what you have. You don't never wanna over describe something and sort of guess well, you know, he probably wants us to say this. Like I only want you to describe what's there. Because that's one of the core things you want to describe what's in the on the page. Alright. So we have a few configurations. We talked about most of these last week. There are a couple of surprises on there that, come up in this little slide which are good to cover. So I'll get you guys to just shout them out if you know them. We'll start I won't jump. I'm not a good jumper. It's low on my list of skills. My daughter is good. I'm not a good jumper. She's a dancer and she's good. But I think she's mine because she has certain things that match me, but anyway, not the jumping. Top left is Flat. Flat. Right? Flat means within 20. Not always perfectly flat. Right? So it's not changing by 20 from one side of the audiogram to the other by 20 dB. Below that? Sloping. Sloping. Yeah. Which means that it is changing by 20 dB going down. And then if it goes up by at least 20 dB? Rising. Rising. Okay. So flat sloping rising. These are your most common. Rising is a little less common. Or a lot less common than you would say. Middle top. Precipidus. Precipidus. Yeah. And it's fine to say ski slope. That's that's also fine. People say ski slope or precipitous. The fun one in the middle? Cookie bite. Cookie bite. Right? A lot of bugs with the cookie. What about this, so we did talk about this. Anyone know what this is? It's a reverse cookie bite. It's the cookie's name. It's a reverse cookie bite. You're cookie you're eating the wrong side of the cookie. You've lifted up the audiogram and I don't know. You could have said mountain or something. Anyway, it's a reverse cookie bite. That's what it is. We didn't talk about the upper right. Any guesses as to what that would be? It's really a hearing loss just in the high frequencies. What would you call that? High frequency loss. No fancy name for it. It. This one we have not talked about. It will be hard to guess if you don't haven't heard it. Does anyone Sorry. There's one there in the middle. There's just a little bit of hearing down in the bottom left corner. It's called a left corner audiogram. A left corner. So when someone has, often when they have a profound hearing loss, when someone has a lot of hearing loss, you will often see a few thresholds in the very low frequencies at the highest level. So left corner audiograms, that's what it means. There's a little tiny bit of hearing in the low frequencies at very high levels. Very common. You see that almost more than you see a completely dead ear, like there's nothing. You often see new thresholds. Remember that low frequencies, they have to go through the whole cochlea. Right? So they have to go all the way up. So if you're playing a low frequency, you're stimulating a lot of the cochlea. It's like you're sticking your finger into the whole cochlea and shaking it, you know. It's, so you often do get some left corner. So if someone says he's got a left corner audiogram, you know, oh, he doesn't have much much hearing. This one you might know because I think I've mentioned it. 4 k notch? Yeah. We did and we did last week. Okay. Yeah. 4 k notch. And it could be could have a 3 k notch or a 2 k notch. 4 k notches are a classic sign of noise induced damage for a very simple reason that we won't go into now. But if we have time or if you're interested, we can chat about it. It'll it'll come up later. Alright. Any questions? Those are the core configurations. So you're gonna describe some combination of degree and configuration. So you might say 4 k notch that smiles or 4 k notch that's moderate or to be more concise, that's a moderate 4k notch in the right ear. That kind of thing. That kind of Alright. So let's go let's go through some examples. Alright. A little bit of background first just so that we're remembering how audiograms work because I know we covered this just once last week. When we do any air conduction testing, so that's speaker, headphone, earphone, anything that's naturally going to go down the ear canal through the eardrum, through the ossicles, that's all air conduction. Right? Because it starts in the air. So any kind of air conduction audiometric measure will pick up any amount, any hearing loss. It doesn't matter where the hearing loss is because we're starting the sound from outside the person. It has to go through the whole system. So if you have cochlear loss, right, sensory neuro loss, you have fascicular problems, eardrum problems, middle ear issues, earwax, ear plug, anything will all affect your air conduction threshold. So that shows you the total amount of hearing loss. And that will typically be the lowest line on the audiogram, your air conduction thresholds. It shows all hearing loss. Okay. Bone conduction will only show, because you're vibrating the skull, you're really testing cochlea and beyond. It's not a 100% true. Remember the ossicles contribute a little bit and so on. But, for the most part we're testing, the sensory neural system. Right? The sensory organ and the neural pathways. So bone conduction measures are an estimate of sensorineural hearing loss. K. If all of your hearing loss is sensorineural, your bone conduction should match your air conduction or be close to it. Right? If the problem is here, it's gonna affect my thresholds regardless of whether I use a bone oscillator or start from out there. Right? The problem is in here. Whereas if you're having trouble getting to the cochlea, let's say you have an ear plug in and I'm testing the cochlea, it's fine. Right? So that my bone conduction will be in the normal range. I have no sensory neural loss. In that case, it's the difference between them that tells us something. It's the it's the trouble getting to the cochlea, and that tells us the conductive loss. Another term for the so this is the difference between air conduction and bone conduction. Okay. You will always have more air conduction, more than bone conduction. Or they'll match or if anything bone conduction thresholds are better. Better. K. Your bone conduction can't really be worse than your error because how can you have more sensory neural loss than total loss? Right? Like if you have sensory neural loss, it's part of your total loss. The reason I say that kind of like, you can't really have more bone conduction, worse bone thresholds than air is there are calibration differences. So sometimes your bone will come out a little lower than your air, like 5 dB. That's just calibration. It can't really be lower. So it will show up a little lower sometimes because they're calibrated differently. Okay. So ac minus bc shows you conductive, Which means if the ac and the bc are the same, one minus the other is 0. There's no conductive. That tells you the sensory neuro part. If they're different, there's a conductive component. The other term for that that we often use is the air bone gap. And you might see abbreviated ABG with sometimes. Air bone gap. It's the difference between the air thresholds and the bone thresholds. So air bone gap is kind of a proxy, a way of saying conductive hearing loss. Alright. So if you know those core concepts, you should be able to read audiograms and describe them. So here's one. What ear are we looking at, first of all? Right. Right. Right red round. Right? So that's right ear. Right ear, our bone thresholds are the little, the unmasked bone thresholds are those little, less than signs. So they're pretty close to the air conduction thresholds. Right? They're not going to match perfectly. Remember, air conduction thresholds are affected a bit by ear canal acoustics and all of that, bone or not. So they're not going to match perfectly. But they're almost the same. So what does that tell us? There's no, what kind of loss? There's no air bone gap. Right? Exactly. So no conductive loss. The air Exactly. So no conductive loss. The air thresholds are also within they're not past 25. Right? So there's no there's no hearing loss at all. That's just the normal hearing. And that's all you really have to say. You would say normal hearing right ear. Or right ear normal hearing. Right ear normal. In fact, on an audiogram typically audiologists tend to be pretty concise. Like I would probably put r circle normal. Like I wouldn't waste time writing a paragraph. It's just that's it. The only reason you'd write it is that the person reading it might not know how to understand your symbols. You will write more in a lot of cases. You know, if it's a child going to the school, you're gonna want to describe it more for people who don't know about audiology. If it's your file or you're sending it to an otologist or something, they they understand what that means. Okay. Here we, here we have, did anyone just wanna take a stab at describing this all the way through? I feel like I'm feeling brave. I feel like I'm like echoing. Am I? Man, It's really crazy. Even if I stand somewhere different. Is that better? There? Yeah. I might go blind, but, okay. So this one let's go oh, you wanna try? Sure. Yeah. It's a right ear mild, not the earring. Bingo. Perfect. Yeah. So it's right ear, red, right round. It wouldn't always be red, but the circles. It's mild, right, because it's past 25, but it doesn't go past 40. It's mild. It's flat, right, it doesn't change by 20 dB. And the the bone thresholds are in the normal range. So there's no sensory neural loss. The bone thresholds are right up around 0. No sensory neural loss there at all. Right? The hearing loss is only in the air thresholds. So that means there's some problem getting to the cochlea. If I test the bone thresholds, if I test the cochlea directly, it cannot normal. So this is a conductive problem. Problem getting to the cochlea. This it's all air bone gap. Right? So the difference between the there's air bone gap, there's a conductive loss. Right? And then the red blood here. Any questions about that? So that's right, conductive, mild, flat. Those are the 4 things. Now, I do wanna warn, I'm gonna slightly revise this later on if you're going back through your slides. Because those bone thresholds aren't masked in practice, if I ask you that on an exam later on, you don't actually know that it's conductive. But we haven't got them yet. So let's we're just assuming that's from the right ear, we'll say this is conductive. So just if you wanna put a little note on that slide, we're gonna revise this. So if you're studying later, it doesn't mess you up. What about this one? What area are we looking at? Left. Left. Right? What's the configuration? Sloping. Sloping. Bingo. Right? It's just changing by at least 20, And it's sloping from what to what? We're going from Mild to moderately severe. Perfect. Mild to moderately severe. So it's a left, a left, and what kind of loss is it? Sensory neural. Sensory neural. Because air and bone match. Right? So there's no air bone gap. There's no conductive hearing loss. So what we're looking at is a left sensory neural hearing loss sloping from mild to moderately severe. Or you could change the order. You know, it's the left hearing loss scoping from the mild to severe range. That's sensory neural. You know, whichever order. It's all fine. You know, those are the things you wanna hit on when you see that. You don't wanna go into describing little changes in the shape along it. That's what the audiogram is for. If that matters, a person who's gonna be able to use that information in a helpful way, like to program a hearing aid or for surgery, we'll understand how to read the picture as well. Alright. So this one's a little different. One thing I haven't said is we don't separately describe degree and configuration for the bone thresholds. We never do that. We always describe the degree and configuration of the air thresholds. Okay. The bone thresholds are just there to tell us type. So in this case, again, we've got what which ear? Left. Right. And what's the configuration? Sloping. Sloping. Right? And we're sloping from what to what? Moderate to severe. Moderate to severe. Exactly. But sloping from moderate to severe, left ear, what kind of hearing loss? Mixed. Mixed. Right? Because we have an air bone gap, so there's the conductive component right there. But the bone thresholds themselves are below 0.5. So there is a sensory neural loss. The bone thresholds are telling you the cochlear component, the the sensory neural component. So if we had surgery to correct the conductive component, we can in theory get back up to those bone that bone line. Okay. If you know, maybe your ear was plugged, something like that. Right. Or, I mean, collapsing canal. Maybe you tested with a with a, TBH or supra aural phone and the ear canal collapsed so it created a conductive hearing loss on top. Right? That's the kind of thing that would give you a false mixed loss. Alright. This one's a little strange. What's the configuration of this? It's really like a reverse cookie. Yeah. Someone might get really pedantic and say it doesn't go up by 20 dB on the bottom, but I would still call it a reverse cookie bite. Like it's that's you want something that describes it that when people see it they say, oh, yeah. I get that. Right, because it only goes up by 15. But then, yeah, it's really a reverse cookie bite. The other you could also say flat to 2 k and then sloping above that. You know, one of those is you're close enough, I think. Which ear? Easy. Right? Right. Yeah. What about the type of hearing loss? Mixed. It's mixed. There have been debates over whether you should call this conductive at some frequencies, sensory neural at others, or call it mixed. I've seen online debates saying it has to be mixed at one frequency. It's which is dumb. Who cares? Right? As long as the description makes sense to the person you're writing it to. I think what you want to do in any case is indicate I would say it's mixed, but it's conductive in the low frequencies sensory neural on the high. That's what I would say. You have both kinds of hearing loss. It's conductive at 255100. Sensory neural at 1 k and above. That's what I would say. Right? You just wanna make it as clear as possible. That's that's the goal. And then configuration, you're in the what range up to 2k? Sneaky. Yeah. But then but then up 12, you're technically in the sorry, you're at moderate. Moderate and then you go up. You go down to you go down to moderately severe here. Right? But up in this range, you're in the moderate and then you hit on 40 is technically mild. So it's a mild to moderate loss up to 2 k, sloping down to moderately severe at 8 k. It's a little seedy because 55 is the bottom edge of moderate. 40 is mild. There are a few different ways you could describe this. You could say relatively flat mild to moderate hearing loss to 2 k and sloping down to a moderately severe loss. Or you could say reverse cookie bite, moderate in the low frequencies, mild mid frequencies, moderately severe or not. You know, so there's a few different ways you could describe it. You'd want you'd wanna include those words. You want to mention probably that it's conductive in the lows in sensory neural at 1 k and above. Because that's important. Right? That's, this is something that in theory can be it's probably transient. It might be some issue that can be easily handled. That would be an autologie consult. High frequencies, likely a permanent loss. Right? So they'll likely want a hearing aid, or some other support. Alright. This one's more straightforward. It looks like a lot because now we're seeing 2. But, we just do each one. We do them separately. Right? It starts to get like, there's so much to describe. So we'll just go step by step. Let's describe the right ear. First of all, what kind of hearing loss are we seeing in the right ear? Sloping? Oh, yeah. I'll ask a question. You're doing figure 8. Yeah. Alright. So we're looking at sloping and and what type? Sensory neural. Right? So there's a sloping sensory neural loss in the right ear. And what's it sloping from? Mild to severe, profound? Yeah. I mean, technically, what I would say I mean, 25 is technically normal. Right? So it's right at the edge of it. So you'd say normal to, severe. Normal to severe, really. Sloping it it the right it's a right sensory neural loss sloping from normal to severe. And then in the left ear, what kind of hearing loss? What type? Is that conductive or sensorineural in the left? Sensoryural. Sensoryural. Right? Those are, masked bone thresholds in this case. And what's the configuration? Flat and sloping? Yeah. I mean that's probably how I describe it. You could just say sloping if you want because it slopes overall. I'd be tempted to say it's relatively flat to 4 k and then sloping after that. Both are accurate. Any way they wanna sort of like how how much you're swinging. Okay. And you're going from where to where? Go from 50 is moderate. And you go down to 95 is profound. Right? Sloping from moderate to profound. Or you could say relatively flat, moderate to moderately severe loss to, 3 k and then sloping to profound. Okay. Yep. So to keep it simple, I would say always past. So it there isn't a perfect agreement on that. Like if when you're reading, people are a little loose. They'll say 90 is profound. But just to keep it straightforward. So up to that level, we'll always be we'll always do the next level at, like, one pass. So 91 passes profound. Yeah. And you will see different opinions out there, but just to keep it consistent for class. Because just people, you know, people will say 70 to 90 is severe, 90 to a 100 is profound. Well then what's 90? Right? And in practice, it would probably depend on whether most of the frequencies were above or below and and so on. But, so up to 90 will be profound and then 91 sorry, severe. And then past 91 and past will be profound for a class. Makes sense? Okay. This one's starting to look more complicated. Now let's just go step by step. It'll all make sense. Right? Right ear, what are we looking at? Sensory neural. Right? Because the bone thresholds kind of match the air. And up to 1 k, what's going on in the right ear? It's what? Normal. Right? Yeah. We don't even describe configuration of the normal range. It's just it's normal. Right? We're not interested. It's normal. Go see someone else. It's, you know, not really. Sometimes people have don't have hearing loss. They have other issues that we deal with. Right? But that's a normal normal threshold up to 1 k. And then at 1.5 and beyond, what do we have? It sort of at one frequency it does. Yeah. I would I probably wouldn't say ski slope because it just it just drops 20 dB and then it's flat. So ski slope, I always think it's more, you know, that's like Bunny Hill ski slope. Right? It does I would be tempted to say, normal to 1 k, a relatively flat or flat hearing loss from 1.5 to 8 k. Like, you know, above that day k. You could also say sloping from there down, you know, is fine. Depending whether you're describing how you're how you're saying it. Right? So it's if you're starting at 1, it slopes down to 8 k. If you start at 1.5, it's kind of flat to 8 k from there. Both are fine. And what amount of hearing loss do they have? What's the degree? 30 is mild. Right? And 45 is Moderate. Moderate. Right. So you're outside the mile range. So so you could just say normal to 1 k sloping to a moderate loss at 8 k. It's fine. Moderate sensorineural loss. You could say normal to 1 k and a flat mild to moderate loss from 1.5 to 8 k. Both of those are the options. Alright. What about left ear? Those are masked air symbols. We haven't seen them a lot. Those are one of the other symbols you want to know from the symbol page. So left ear masked. What's your degree in configuration? What's our configuration? Sloping. Right? We're sloping and we're sloping from 35, which is Moderate to moderate to severe. Yeah. Mild to moderately severe. So mild to moderately severe sloping loss. Because 70 would be the highest threshold we call moderately severe. What's the type of loss there? Most of it's conductive. Yeah. Because there's a big air bone gap. But then the bone thresholds are 30, 35. So they're technically there's a little bit of sensory neural loss too, a tiny bit. So so what would overall mix. Right? Yeah. Most of that's conductive. So it's a mixed left ear has a mixed hearing loss sloping from mild to moderately severe. Does all make sense? Sorry. Say that again? Do you know if it's like actually going down? And it's like the 20 decimal rule? Yeah. Yeah. Is that it has to go like, for instance, like 30 to 50? Yeah. So because it's like we're at 35 and we end up at 70. So it's a 35 dB change across. So you're really looking at like, the left. Actually, it's interesting that they did 125 hertz on this on these. Right? Usually, we start at 250. But, any case, it's 20 it's 20 bb from the left to the right, like all the way across. The only one where we're comparing, like like, neighboring frequencies would be when you're saying it's precipitous. And typically it's when it's kind of dropping quickly. Otherwise, you're always looking at sort of like how does it change across or across a wider range. Because you you can describe a subset, you know. You you could say from 1.5 to 8 k it's flat. Right? Because it's really not changing by 20 feet in that range. But typically, we don't explicitly describe which frequencies we're looking at. We're talking about the whole shape left to right, which is the most common. Alright. What about this one? They all have down arrows. Vt, as a reminder, means vibrotactile, which means that the suspicion here, because it's vt question mark, is that maybe the person felt the bone oscillator, which is, when you're at low frequencies, like 250 and 500 hertz, and it's intense, you can often feel the vibration. You're not hearing it. For that reason, a lot of clinics don't even do bone conduction at 250, at 250 hertz. Hearing and speech in Nova Scotia, they don't. Because if you turn it much above 0, people will often feel the vibration, which is in a hearing test. You can ask the person and sometimes they'll say, I didn't hear that. I felt it. In which case you can just write v t. But this person's the audiologist is insured so they put v t question mark. Yeah. I was gonna ask that earlier about profound hearing loss because obviously you'll feel the pressure of such a loud sound. So what do they do for that? For the air conduction, it shouldn't be it should only be for the bone conduction. Like, you shouldn't feel the air pressure, like, physically for the sound. At least at the limits of the audiometer. Like, if you went far enough, you know. But for the bone oscillator, yeah, there's gonna be limits. In fact, for profound loss, you often can't you can't really fully describe the type at a certain point because your bone oscillator only goes so high. Like, it only goes 270 on this audiometer. So you it won't ever match the air thresholds. There's an assumption that at a certain point, the loss is sensorineural. Because typically, you can only get about 60, 65 dB of conductive loss. So we just assume, but we can't actually bring the bone thresholds past that. We could at a certain point, you would just feel it, which is the, yeah, the issue. So in this case, really there are 2 thresholds that does that make sense? Yeah. I don't think it answered the question. Pardon? But because, like, for profound hearing loss Yeah. If you're doing a hearing test, maybe not the phone one. Yeah. If they're playing a really loud sound, like, I don't know, a 100 decibels Yeah. And you would feel the vibration and, like, maybe the patient, like, jumps or something. So how would you They shouldn't feel a vibration from it. Oh, okay. They shouldn't. Like, unless if you're using a TBH phone, you can get a vibration. You can get a vibration that's about 40 dB below that. So it's possible that if you were at, let's say, a 100, and be getting a vibration at 60 at a low frequencies, they might feel it. Just one of the reasons why we should use insert phones because that the vibration would be much lower. Because that could arise if you were if you were using t d h headphones at really high levels. Yeah. Just one of the downsides of using those kinds of earphones. That's a good question. Yeah. So for bone conduction, you can only go up to 65 decibels. Is that correct? Depends on the audiometer. Okay. Usually, your limit is somewhere in there. With the with the most audiometers uses a few versions of different bone oscillators like, you know, the b 60 or b 70. I forget the exact numbers. But there's a few different ones. But they all have limits around that range. And would you still Depending on the frequency. Would you still test at, like, each frequency? Or is there a certain range for the frequencies as well? You only go up to 4 k. Okay. You don't go higher than that. And all and again, a lot of clinics won't go won't do 250. The clinic, I worked at for a long time before I went back, you know, before I left clinical work. We did do 250. But we you know, once it goes like at 0 and 10, often it's you're getting a good threshold. It's only when you start to raise it up that you often get the vibrotactile. Yeah. And you shouldn't for air conduction, but you you could for the supraoral, which is yeah. Never had anyone asked that before. It's a good question. Yeah. Yeah. It's another reason why typically now we use insert foams instead of the little foam ones. So you shouldn't feel that because there shouldn't be much vibration with it. So in this case, all the arrows are pointing down. The only two thresholds we got were vibrotactile. So we didn't actually measure any hearing. So that's just no measurable hearing. Doesn't mean that there's no hearing. Maybe with an audiometer that we filled out or we'd measure hearing. Right? It just means with our test, we didn't measure any hearing at the limits. And where these are marked tells us how far we tested. Right? This is the limits. So all it's saying is all all is all that this is saying is that the threshold is passed this if there is a threshold. I wasn't able to get it. And sometimes you're using, you know, a device that doesn't go as loud, and maybe you just couldn't reach threshold. You wanna retest them with different audiometers. Right? Typically, they all go through in the same range, but, the clinical ones. Okay. Yeah. Is it a threshold that the air bone gap has to be to call it 1 layer? Yeah. That's a good question. Yeah. So is there like an air bone gap size that we have to have to call it? Yeah. So there are 2 schools of thought depending on which chapter, which book you're reading. Some will say it has to be 10 dB or greater. I like to say greater than 10 dB. That's my preference. Just a personal preference. Because of calibration issues, I think a lot of times with 10 dB, it's not true conductive loss. Where it changes a little bit let's say the person has a conductive pattern across multiple frequencies that's greater than 10 dB, then at one frequency it's just 10 dB, and it's probably still conductive there. Right? So I would use the whole pattern. But, yeah, my preference is greater than 10 dB is is a conductive component. But some will say 10 dB or greater. In practice, because of calibration, it's hard to tell. I don't I don't yeah. I don't have a strong preference. That's just where I land. Alright. This one here. So let's not too complicated really. The left ear is simple. Right? Left ear we got we have, it's the blue, right, with the x's. It is What's going on? That's a lot of sloping. Right? It's certainly precipitous at a lot of frequencies. You almost don't have to say precipitous when you give the range, but what's the what's the range? It goes from normal to profound. Right? Sloping from normal to profound. K. It goes the whole the whole way. You certainly could say sloping precipitously from normal to profound. Typically, where where the precipitous matters more is when it's sort of flat and then falls off. Right? In any case, you know that's a huge change across the frequencies. And as far as we can measure to the limits of our of our bone conduction, this is what? What what's our type? Sensory. Sensory. Right. Angle. So it's sensory neural hearing loss, left ear, sloping from normal to profound or sloping precipitously from normal to profound. The right ear is a little is harder to describe, isn't it? It's there's not you're gonna have to use a few more words. So what are we taught what what's our configuration in the right ear? It's for a burst drift device. Yeah. Classic. Right? It's low. It goes way up and goes way down. I would probably describe the low and high frequencies separately and and the island of better hearing in the middle. Right? So you've got down here 70 to 85. We're looking at moderately severe to severe. Right. What about in the high frequencies? We slope down to severe. Right? 75. Right? And then in the mid frequencies, we are at what kind what kind of hearing loss? Mild. Right? Like 35 to 30. Okay. So it's a reverse cookie bite that's moderately severe to severe in the lows and, moderately severe to severe in the highs and mild to the mid frequencies. What's our type of loss there? This is where the audiogram picture is better. Complicated hearing loss, like, look at the picture. It's just yeah. You're not going to be able to easily use a description to fit a hearing aid or something like that. Where that might really matter is do they qualify for certain benefits or supports in the school and things like that. What what what's the type of hearing loss there? It's a sneaky one. It's hard to know. Right? Because of those thresholds could be fibrotactile. Yeah. Right. Because these are vibrotactile potentially. This is this could just as well be sensory neural. Right? Because I don't really have I'm not confident that the the cochlea is any better there. And it's sensory neural in the high frequencies. So I'd say likely sensory neural. You know, you there's no way to con to to know whether this bottom component is conductive or sensory neural. You certainly know it's sensorineural in the high frequencies, but this could be a conductive overlay there. It's possible. That's where you do other tests to see if there's something around the middle ear. How does otoscopy look? All those those things we factor in. Because it's a weird shape. Right? It's possible something else is happening down here than what's happening up here. So it's possible that it's mixed. Hard to know. Hard to know. It's limits limits of bone conduction. Alright. We're almost done. We'll we'll we'll break. This one's a nice succinct one to describe. Right and left ear. What's our type for both ears? Sensory neural. Right? And our configuration title is the same for both these. Right? Those are notches. Right? So in the right ear we have a what a notch of what degree? In what frequency? Sensory. Yeah. So it's sensory neural 3 k notch, that's 1 in degree. 55 would be moderate. Right? Moderate. In the left ear, we've got a 4 k sensory neural notch that's moderately severe. 4 k moderately severe sensory neural notch or something like that. Some arrangement of those words. Makes sense? Looks like a fairly advanced noise induced loss. Typically, these higher frequencies would come down afterwards. Other other possibilities, but, you know, assuming it was supported by the case history, that would be kind of a classic. Alright. Now nice easy one. Finish off. What's our ear? Tight. Type of loss Right? Synty neural. Right? Going in a match, and we're going from what to what? Normal is profound. Yeah. And it's a fairly sharp drop. Right? It drops, actually it's profound by 4 k. It ends up being fairly precipitous. Right? So yeah. So I'd probably say precipitous. I probably would in this case. Yeah. It really does drop fast in the middle there. It's a sharp drop. You know? Yeah. It it drops precipitously above 1 k. Right? Any questions? It's good. I think that's our last Can I ask one question? Yeah. How how quickly does it have to drop a answer to be called precipice? 20, really. Between neighboring frequencies. 20 minutes ago. Yeah. And this is between the octave. Right? So this actually goes down 10, 20, 35 dB between 12. That's a really big drop if you wanted to. So you, you know, you could say with a precipitous drop at 1 k or something, if you wanted to add a little more information to it. Can you describe it as precipitous if you don't look at the whole thing? Yeah. I mean, you can just say precipitous for the whole thing, like, and they'll look at it too because it's it won't there's no way for it to be, well, I'm trying to think mathematically for it to be precipitous at every frequency. Overall, it's it's there's really only a precipitous drop here. The rest is is technically doesn't qualify. I think if I was writing it, I'd probably just say, you know, precipitously sloping from normal to profound at 4 k and above. But you could say, you know, a precipitous drop, particularly at 1 to 2 k. If you wanted to add that, that's fine. Yeah. There's no sort of perfect answer there. But you don't have to you don't want to get too into the weeds to describing a lot of different things. It's better to kind of make it succinct. And if you want to add a little context to kind of paint the word picture, that's okay too. And you don't want to say sort of like, you know, sloping to 500 hertz then precipitously dropping, then sloping and then dropping to profound at 4 k and then flat above that. Like, that's a bit too much description. At that point, you'd say, look at the audiogram. You know, it's really Yeah. Yeah. Why is bone conduction done in between opt ins for air conduction? You mean, like like in this case? Or like it's normally we wouldn't. It's only because the air conduction was done between the octaves here. Okay. Yeah. I think all the ones we looked at the bone conduction was in between. Oh, I think it's just the way it's drawn. It's drawn a little bit to the left of the axis for, in this case, for the right ear. Like, almost as if it's a little face with every ear. Like it's it's often not drawn right on the axis so that the symbols can be side by side. Yeah. So so the, like this one that's at 1 k, it's not really on the 1 k line, but it's meant to be 1 k still and so on. Yeah. Yeah. Yeah. It's, and it, you know, varies by audiologists how close those are, but they're usually a little displaced just because to to make space for them all. Yeah. The the other thing, like, the reason why the interoptics always is if you have a 20 degree change between frequencies, we'll always do the interock. You don't really know. It could be that, you know, it's, like, flat to there and then drops, or it could drop mostly here and then be flat. And that would matter if you're fitting a device or something. Like, what's, you know, if I know it drops so much by 2 ks, what is it in between that? Is it is it between 1.5 and 2 ks or 1 and 1.5? There's a lot of speech information in there. So if there's a 20 dB change between octaves, we do that inter octave for all of these. Alright, let's take a break and then we'll come back and end up with, asking. So bone thresholds, if we come down to them, they're always telling us about wait, my friend will send me a message. I used to do my tablet, but I can't seem to record it. So I don't know. There are a few people that wait sick. Bone conduction tells you about the cochlea. So you go down to the bone conduction to see if there's sensory neural loss. And if there's anything beyond that, that's air bone gap, that's conductive, if it's greater than 10 dB. This is a case where you can see a conductive component across the frequencies. If it was, like, less than 10 dB at one frequency, I would assume it's still conductive. Probably there too. It's like Alright. So with that Just checking. We're gonna move into masking. But before we move into masking, this is a because this is a shift. Any remaining questions from the first part? You may not you may not have memorized all the levels yet, which is fine. A couple more weeks. You'll have the test, then you will wanna know them. Any other questions? Yeah? Is there a Yeah. We really always default to 250. 125 is rare. You'll probably be looking for a particular thing. So, I think 2 weeks ago I mentioned one condition where you can have a small, crack on the semicircular canal that opens that, you know, lets the cerebral spinal fluid kinda go into the ear. That, which is called superior canal dehiscence, that often shows up as a as a strange feature in the low frequencies. So an audiologist might go do 125 to get more information, but 250 is usually the starting point. The default is always 250 to 8000, in 99% of audiograms. We are starting, to test what we call ultra high frequencies, which is anything above 8,000 hertz. Because that's really useful for looking at it, like noise damage and ototoxicity and stuff like that. But otherwise, always 250 to AK is the standard. Yeah. You don't usually see 125. It's rare. Good question. Not relating to that. Yeah. Are you recording? Because usually, like, it's your face. Like, we just I think I am. Let me check. Yeah. I I I try to minimize my face. Okay. I think I am. Yeah. Yeah. Yeah. And the red line means this is what I'm yeah. Should be sharing. So it should be good. I hope so. Yeah. Because masking is something that, like, you really wouldn't it's tricky. Not super tricky. Don't, you know, don't worry about it. But it's easier to be explained. It'd be hard to just pick it up from reading the slides. It would be a tricky one. Alright. So basic any of the other questions? Basic principle with masking is that people are two sided. Right? Which is kind of weird when you think about it. We're used to it. It's weird that we have, like, 2 eyes. And Like, what if we had 2 noses? That'd be weird. Right? Because we don't. But we're so used to having 2 of everything. We're 2 sided. It's weird. We're like 2 halves glued together with a tube in the middle. You know? Sorry. Sorry. I don't know where that came from. And we're not always symmetrical. Right? Like, her face is pretty symmetrical. Right? Sorry. I don't know why I'm putting him up this way. Whereas his face, particularly in the way the picture is framed, does not look very symmetrical. So if you stick the sides together, he looks bizarre whereas she looks fine. Right? Sometimes symmetry is considered, you know, an element of attractiveness. Although you get attractive people with asymmetric faces too. But our ears can be asymmetric. And our vision our eyes can be too. So we need to test both sides. It's not okay to test one side. We always have to do both. We have to be able to separate what we do for the right and the left because we can can have asymmetries. And the asymmetries are often really informative. So, you know, optometry, they get off easy. Because if you want to test one eye, you just cover the other one. You hold something up or super super easy. It's harder for audiology. Because when I play sound to one ear, I'd like to think we're just playing sound to that ear. It will bleed over at a certain level and get your other ear. Sound is like water. You know, it's a vibration. And it'll I'm not saying water is a vibration, but it kind of goes where it wants. Right? Like, you know, if you've ever lived next to someone who likes to throw a lot of parties, it's hard to con you know, to confine the sound to their condo or apartment. Right? Or if you're the one throwing the parties, it's like, you know, it's it's a perennial issue in human relations. The fact that sound goes where it wants. This is a problem in audiology. The problem is greater if we're using headphones than if we're using insert phones, which we'll talk about right here on the next slide. So the primary way unless we're if you're using speakers and the ears are open, sound very much goes to both ears. It's a little more intense in the ear facing the speaker. There's a bit of head shadow that reduces the level for the opposite ear. It's small though. Goes to both ears. If you're using headphones or earphones, you you hopefully can mostly test the one ear. Right? So I've I've chopped the person's head off here, so you can just kind of, like, focus on the cochlea They're embedded in the petrous bones and there's little happy faces. Those are your the cochlear inside the petrous bone in the bottom of the cranial cavity. Okay. So if I'm testing with a headphone and I'm playing a fairly soft level, I can probably be confident that I'm testing that here. As I let's say I don't get a threshold at 0 dB. Let's say the threshold I measure is 80 dB. It's a pretty intense level coming out of that headphone. So if I'm playing 80 dB out of this, let's assume it's one of these TDH headphones, a big headphone, that is sure, it's gonna send sound down my ear canal. It goes through my eardrum and my ossicles and as I expect. But it's also gonna vibrate the ear a little bit. Like, that's a pretty intense sound coming out of this big speaker. It's gonna create some vibration of the skull as well. And if I'm vibrating the skull, I'm vibrating the whole skull. It's one big bone. Right? They're all it's all connected. Once you're an infant, then you guys are not. It's all connected. So if I'm vibrating the skull, I'm actually vibrating both cochlea. I'm getting them both. So once this is loud enough to transmit some vibrations to the skull, it gets to both cochlea. Okay. It's it's gonna be probably a lot more intense, louder in the one you're that's near you because it's also going down the ear canal and through the eardrum and through the ossicles. We then match the impedance. You know, it's not it's an there's an efficient pathway. But that vibration of the skull will hit both cochlear. If I'm using a bone oscillator, I'm just intentionally vibrating the skull. I'm actually testing both cochlea. Even if my bone oscillator is on one side, and typically it is, until I use masking, which we're gonna come to in a bit, until I start doing masking. When I test unmasked with a bone oscillator, I'm testing both copias. Which one responds is whichever one here is better. So unmasked bone just tests the better ear. That's it. No matter which side I put the oscillator on. So the question is, when does this vibration become a problem? Alright. My hearing is fairly symmetrical. Alright. Let's say I have a 70 dB hearing loss, 70 dB HL in both ears. Okay. So I have to raise my headphone level to 70 dB to reach threshold. That's not going to be putting 70 dB to the other side. Right? Because it's not vibrating the skull that much. It's mostly going down the ear canal. There's some smaller vibration which is likely below threshold over here. Where I run into problems is when my ears are asymmetric. If my hearing is much better on this side, maybe I'm hearing the vibration. Let's imagine that there's no hearing on this side at all. Nothing. That ear is just never worked. Let's say there's no cochlea in there. Nothing at all. Right? So I'm going to eventually get to a point, testing on this side, where there's enough vibration that this ear will hear it. And if I don't know about this as an issue, I'm going to say, oh, this ear here is at that point. But it's really just the vibration going through to this side. Okay? This is why we need masking because when I'm testing, some of that sound will leak over. With a bone oscillator, all of it leaks over. It gets both copias. But with a headphone, some of it will leak over. If I'm using an insert phone, so that's a foam tipped little earphone, foam does not transmit vibrations well. Right? That's why you see, like, soundproofing often uses foam and, you know, harder foam and things like that. Right? So this is less of an issue. It's still an issue, but less of an issue. Right? Because with the foam tip, not many vibrations get through to the skull. Also, not to put too fine a point on it, but with the foam tip earphone, it's deep in your ear canal close to your eardrum. So to create that same pressure at your eardrum, I don't have to put out as much sound from the earphone as I do from an earphone that's here. If I want to get 7 dBB, you know, HL, at your eardrum With with a t d h headphone, that's more sound energy coming out because it has to go all the way down your ear canal than it is when I have a little foam tip up close to your eardrum. There's only a little tiny air pocket left. So so I'm using if I'm using foam tips, I'm reaching the same thresholds with actually less energy coming out of the earphone. And it's foam surrounded so it doesn't vibrate the skull as much. So it makes there's less there are fewer masking issues. There are fewer issues where sound is bleeding over to the other side. Okay. So that's one of the reasons we really like these phone tipped earphones. So if I'm using the tDH or supraorals, so the the the big ones that clamp your head, We the amount that it will vibrate the skull has been measured in lots of ears. And we know that it may vibrate the skull at a level that's 40 dB below whatever sound I'm presenting. So if I'm presenting 80, it could be vibrating the skull at 80 minus 40, which is 40. I'm just backing up. If I'm presenting at 50, it could be vibrating the skull at 50 minus 40, which is 10. Okay? 40 dB below. This drop is called the intraoral attenuation, which seems like a strange thing because intraoral means between the ears. But we usually think about that sound vibrating the skull. The problem is it leaks over to the other side, so we use the term intraoral. K? So for TBH headphones, I may only have 40 dB of intraoral attenuation, which means it's pretty good at vibrating the skull. If I'm playing it sound at a 100, how much might I be vibrating the skull and therefore getting to the other side with these earphones? But 60. Right. Now individual ears are all different. Everyone's head is a little different in terms of how well it vibrates. So some people will have more intraoral attenuation. A lot of people will have 60 dB of intraoral attenuation. So I I play a 100, you're only getting 40 vibrating. But the lowest in various studies that we've measured in people is 40. So we assume that it's 40. It's kind of like, if I was trying to figure out, you know, the the the lowest height of a person that the person could be, and I lined up everyone against the wall and the shortest person. Okay. That's the that's the shortest a person can be. That's kind of what we've done. There's been a a number of studies that have looked at intraoral attenuation, and the lowest that they've measured in humans has generally been 40 dB. So some people will only have 40 dB in visual attenuation. If I went to the class, maybe a few of you would. And it varies a bit by frequency. So it's how much your skull likes to vibrate at that frequency. Some people will have fifties, some people have 60. The more you have the better. Right? If you have more intraoral attenuation, the sound I'm presenting doesn't vibrate your skull as much. It stays focused on that ear. Right? So if I let's say you have 60 dB into 60 dB intraoral attenuation and then presenting a sound to your ear that's a 100, what's the level that could potentially get to your other ear? Do you have 60 dB interval attenuation? 40? 40. Right? A 100 minus 60. It's just subtraction. Yeah. Okay. So having a small amount of interval attenuation isn't great. Right? Because it means that more is gonna get over to the other side. If I only have 40 and I play a 100, I'm getting 60 to the other side. Not ideal. But the lowest we recorded for these are 40, so we assume the worst. We assume when we're doing testing with these earphones that we only have 40 dB intraoral attenuation because I don't know how your skull vibrates. Yeah. But if you're outside of testing Yeah. Like you're setting, is there any, like, I don't know. I I like, it wouldn't affect you much. So is there an advantage, like, to having? Like, can you actually, like, telephoto in the real room? It would only be I'm trying to think. There are there are cases where so for for people, if you can't wear a normal hearing aid for various reasons, or there's a couple of different reasons why you might, want a bone anchored hearing aid. Right? So if you have a conductive loss, a bone anchored hearing aid will get around the conductive component. So bone anchored, it's the hearing aid is is actually anchored in the bone. So it's through the skull vibration that the sound is being carried over. And a lot of people over the years have gotten a bone anchored hearing aid to help bring sound over to an ear that can't be aided. So to give you that sound on the other side, in which case, intra attenuation is, like, if your skull isn't vibrated as well, you need to put more energy in the bone anchored. So there are a few cases where the vibration good. Yeah. You probably wouldn't hear it though, mostly. If it's not specific applications like that, you know, it's yeah. It would have to be you'd have ears that would be very different to hear it on the other side. Yeah. Good question. Okay. Is that does this make sense generally? So if I'm playing with an earphone, I kind of want to keep the sound in that ear that I'm testing. If I push left ear on my audiometer and I'm sending it to the person's left ear, I kind of want to be testing the left ear. Right? There it's it's I consider it a problem that at a certain level it's also vibrating the skull, which is going over to the other side of the head. And so the difference between what I'm presenting and what's potential what's potentially going to the other side, that difference is the intraoral attenuation. Okay? So if I'm presenting at 80 and the intraoral attenuation is 40, then whatever is 40 dB below is going over. Right? So if I'm presenting at 80, 80 minus 40 is 40. 40 is going over. If I'm presenting at 90, 90 minus 40 is 50, 50 is going over. Right? If the person had more intro attenuation, great. But I don't know that. So I assume it's only 40 for the easier folks. Okay? I'll I have it in a later slide. If you're using the foam tips, we can assume 50. You don't have to write that. It'll be later in the lecture, but we can assume a little more internal attenuation. The sound that crosses over to the other side, we call crossover. Right? The sound energy. So if I'm presenting with my t d h headphones, and let's say your ear is not plugged or anything, it's it's working fine. There's no conductive hearing loss, let's say. So the sound energy that goes down your ear canal is is traced in this slide by the blue line. Right? Very efficient. Goes down your ear canal. Your ossicles are working. You know, so it's getting to the ear very efficiently. The less efficient pathway is that your head is vibrating and because the bone is vibrating, it's going to the other side. That's what we call crossover. K. So it's it's I've traced it with a red line here. So the fact that that TH headphone is on your head and is vibrating your head is also sending some sound energy across your head, not as efficiently. Right? And that's that's what we call crossover. It actually will get to both cochleas though. Right? By vibrating your skull, it's gonna vibrate the near one and the far one. It's just at a much softer level than what this blue sound is. Because if I'm presenting at, let's say, 80 dB, that's 80 dB going down your ear canal. If your interrel attenuation is 40, a minus 40 is 40. So the red line is only 40. Right. So it's 80 here, 40 on red. It's just a lower level that's crossing over. Almost always a lower level that's crossing over unless you're using a bone a bone, oscillator because that's vibrating the skull. Yeah. Say that again. I missed the first part. Sorry. Like, the blue arrow arrow. Does that get, like, processed before, like, really quickly got before, like, the sound of the vibrations, like, reached the other ear? There would be a slight it popped down, like, I don't think on the other side. There'd be a slight time difference, but it'd be very, very, very slight like that. So the person that will, you know, let's say let's say the close ear isn't working at all or not hearing it for whatever reason. And so they're only hearing it on the other side. Person will often know that. They can tell you. Like, you're playing it from they won't even know which ear you're playing it from probably because, you know but if you say, oh, I'm testing your right ear now. They'll say, I'm still hearing it in my left. Right? So they will know just, yeah. Unless their ears are very similar, they can usually tell which ear is hearing it. There will be a slight difference in timing. I'm not sure. I'd have to you'd have to calculate. You can't so what you're you can have an issue. So you won't get into I'll just mention, we won't get into it in this class because it gets kinda complicated. But if you have the other ear plugged, the vibrations that go through the bone will end up, sort of, being amplified on the other side because you get that extra osteotympanic, like the occlusion effect. So you can get into some situations where it's enhanced on the other side, which are a bit problematic, which when we do the masking practice for for those in audiology next year, we have to take all that into account. But, yeah, we will go that far down the road. Honey, it was just the arrow kinda goes through the nerve and kinda like that. Yeah. Yeah. But otherwise, yeah. It's it's really just yeah. If you're using a speaker, it's actually going around the head externally too. You're is that okay? Sorry. It's not our room. It's med school. It doesn't matter. So, yeah, if you're using a speaker, it goes around outside. Right? But with headphones, it's pretty much all bone connection that it gets to the other side. So really what we think would when it's getting to the other side, it's stimulating the other cochlea directly. So what really matters is how the other cochlea is hearing, whether it's gonna pick up that sound. It's the cochlear threshold, the bone conduction threshold. But let's start here. So terms, the sound that crosses over is called crossover. And it's almost all by bone vibration. Okay. And what crosses over is a lot less than what I'm delivering to that side, unless I'm using a bone oscillator. Right. And the amount that it's less is the intraoral attenuation. K. For a bone oscillator, we assume 0. It gets both cochleas. For a teenage headphone, we'll assume 40. For an insert earphone, we assume 50. That's the standard. Just numbers that we have to remember. So if I'm presenting, I put someone here, at 70 with the a TBH headphone, so I'm assuming 40 dB intraoral attenuation. How much sound is crossing over? 30. 30. Right. 30 is going through the inefficient pathway pathway to the other side. Okay. So intraoral attenuation is always the sound level you're presenting. Usually, you're measuring it's a threshold, usually, because we're doing threshold measures. Minus the level getting to the other ear. It's the difference. Okay. So this term looks like crossover, but it's a different term. Cross hearing. And it's it's different for an important reason. So this is when it becomes an issue. When crossover is loud enough to be heard in the opposite cochlea. So if you're hearing it in the opposite cochlea and not the ear that you're testing, that you think you're testing, we call that cross hearing. K. There's almost always some sound crossing over. Like, when you're there's a little tiny bits of vibration that go through your skull. So crossover is not an issue. Always happens. But when you're hearing it on the other side, that's cross hearing. And that's when we need to mask. When there's the potential that you're hearing it over there, right, that's when we have to mask. Okay. So there's it's probably safe to say that there's always some crossover. But whatever earphone I'm using, little bits of vibration will get to the other side. Typically, that's way lower than what you're hearing in the ear you're testing. Okay. But when you're actually hearing the sound you like, if I'm testing the right ear and you're actually hearing it on the left ear, ear. From testing the left ear, but they're actually hearing it on the right ear, that's cross ear. Yeah. When that happens, would they usually say that they only hear it on the other ear? Or would they say they hear it in both? Usually, if they're if they're able to tell you, they'll they'll usually only hear it in the other ear. Yeah. It's one of the reasons why some audiologists like hand raises because it'll alert often people will raise the hand naturally of the ear they're hearing it in. So it will often alert you right away that there's cross hearing because I'm playing on this ear and they raise the left hand. So or they'll tell you. Yeah. Yeah. Usually, it's it's all or none. It's yeah. So when would this not be the case? When would it not be the case that or maybe I'll flip that around. When would it be the case? When would cross hearing occur for a sound? When would you expect the ear you're not testing to be hearing it? So if I'm testing my right, when would I expect to be getting a response from my left? So whenever you're playing sounds greater than 40 or 50. Yeah. When it So I have to be using a louder sound, a more intense sound. That's part of it. And there's one more thing for that to work. Because usually, if I'm raising the level of a sound, it's because the person needs it to be higher for them to hear it. It's because their hearing thresholds are higher. Right? Like, if I'm raising it to 70 or something, it's because their hearing threshold is 70. And if their hearing thresholds are 70 in both sides, they're not gonna hear these little sounds crossing over. But when would they hear it on the other side? If they have, like, a profound loss on the side. Yeah. Like, it's it's if if the side you're trying to test is worse, really. Like, if it's profound or if it's significantly worse than the other side. If there's a big asymmetry, that's where I have problems. Right? So in other words, let's just do it as an example. Let's say I'm testing the right ear and the right ear has low much lower thresholds than the left ear. Left ear is is let's just say it's normal and I've got a lot of hearing loss in my right ear. So I raise the level up really really high on the right side and the right ear by the time the right ear may or may not be hearing it because I'm going up high, there's enough sound leaking through the bone that they're gonna hear it in that better ear. So it's when the opposite ear is better, and it's better enough to get that little bit of vibration. This the the the level you're testing minus intraoral attenuation. So if I'm, you know, let's say the true threshold here, I'll give an example. Let's say the true threshold on my right ear is 90. Profound hearing loss. Well, severe, let's say, on the on the border of profound. So the true threshold, my right ear is 90. And this person has normal hearing in the left ear. Okay? 90 bb loss in the right ear at this frequency, normal hearing on the left ear, and 40 bb of intraoral attenuation because I'm using TDH headphones. What threshold will I measure in this ear? Let's say their threshold is 0. I'll give a number to it. So it's perfectly it's normal. It's 0 on this side. It's 90 on this side. What threshold will I actually measure? Not even it'll be lower even. 40. 40. 40. Yeah. Right. Because as soon as I get to 40, 40 minus 40 is 0. They get it over here. Right? If I'm using insert phones, it would be 50 because then 50 minus 50 is 0. So as soon as they get to a level on this side, that if you subtract interall attenuation, it's going to be heard on the other side. So in that case, I would say, oh, this here here is at 0 and this here here is at 40. But it's not true. This ear actually here is at 90. It's just because of that cross over sound is being cross heard. It's enough for it to be heard on the opposite side. Yeah. Like, in that case, they would still think that it's coming out of their bad ear? Like, they would still think that they're hearing it? No. They would they would tell you probably. Yeah. Yeah. They would say, oh, I'm hearing it over here though. Yeah. Yeah. Usually they can give you that feedback. Not always, but usually. Yeah. Making sense? Yeah? So basically, the issue across here is, there's some asymmetry here on the other side and it's not so much better. You still have to fix it in order to get, like, the true measurements. Yeah. Right. Because I because even if they say, oh, I'm hearing this in this ear, I still don't know what the threshold is over here. Right? So I'm gonna have to I'm whistling there. I think. Yeah. I'm gonna have to, do something so that this ear isn't interfering in the measurement. Right? And we look into the practice of it, but what we do is masking. I put some noise into that side, I put some noise into that side to take it out to cover it up, essentially, so I can test that ear. Yeah. I don't know if I misunderstand it. I thought you said, like, if we're presenting because you said, k, if they have 90 dB hearing Oh, good question. Good. Yeah. Yeah. No. I get it. Yeah. Yeah. The issue is so if I'm doing the hearing test, I would never get up to 90 because, by the time I got to 40, they would hear it here. Yeah. Yeah. So I would never like in theory, yeah. Like, if I got to it'd be 90 minus the 40, which would be if I by the time I would reach threshold on this side at 90, it would be playing 50 to that ear. So that's yeah. That's right. Yeah. But I would never end up getting there because they would say I hear it. I hear it. I hear it. Right? It's, in theory, you could say, like, tell me when you're hearing it on this side, ends up being really tricky. It doesn't work very well. So we have to use masking to cover up the one side. Does that make sense? So as I go up, really, I can only get as high as the point where they're hearing it on the other side. So, all right. It's a lot to it's it gets complicated because you're thinking about the 2 ears. Not super complicated, but I don't know. I remember when I first learned masking, and my whole class was so confused. And we got together after the class and spent, like, 2 hours together trying to figure it out. Yeah. I still remember how much I hated it. I hate doing it to you guys. But it will it all make sense. It's not super bad. Once you yeah. Concierge principle. So we use a lot of lingo when we talk about masking. And if you read the chapter, you'll see this. We use test ear and non test ear, just to simplify it. So test ear or t e is the ear I think I'm trying to test, and non test ear is the other one. Right? Instead of saying right left all the time. So whenever the input to the test ear, like, usually where I'm trying to see if they hear it like I'm doing a threshold, is greater than the cochlear threshold in the non test ear, cross hearing may occur. So and I left out this by amount that's greater than equal to the intraoral attenuation. Because my presentation level minus intraoral attenuation is what gets to the other cochlea. So if I'm playing at 50, right, and I've got 40 bb of intraoral attenuation, 10 gets to the other cochlea, 50 minus 40. So it's just subtracting that intraoral attenuation. Okay. So, if someone's threshold in this ear let's say it was 40. Let's say the threshold on the left ear is 40, and that's my non test ear. K? And let's say the right ear has no hearing at all. And I'm using tDH headphones to record. What threshold will I record on the right ear without masking? Eighty. Yeah. Because 80 minus the 40 dB interal attenuation for those headphones is enough to get is 40, which is the threshold on this side. Alright. So whenever I'm the interal attenuation above the opposite threshold, they hear it. And so if the if this threshold was 40, whenever I get 40 bb above it on this side, they hear it over here, which is 80. 40 plus 40. It looks super confusing. Do you want me to do another example or do you want to do some yeah. When you're saying all the numbers, could you maybe just, like, write them on the board? Sure. To keep them in mind. Yeah. I can do that. Yeah. It's a good it's a good suggestion. I do have some pictures. So we'll do these with pictures. But I'll I'll write these ones here. Right? So let's let me do I'll do red so harsh. Okay. So let's say this is the person. They're very they're happy, happy, happy. Okay. So let's say this ear has no hearing whatsoever, just to keep it simple. No threshold there. Whatever they only were born with one cochlea. Okay? On this side, let's say the threshold at this particular frequency I'm testing was 50 dBHL, okay, on that side. And I'm using tDH headphones, which have an intraoral attenuation of 40. So what threshold will I measure over here with those TDH headphones? You're gonna have to basically take the threshold on the non test ear, the the better ear, and add the intral attenuation to it. 90. Yeah. Because when I play it at 90, there's sound energy leading across 40 dB below, which is 50, and they're hearing it. That good? Yeah? So which ear are you playing? The 90? So when I play it on this side, like, when I play 90 over here, on the ear that really has no hearing, they say, oh, I hear that. Right? And so I'll mark that on the audiogram as an unmasked air conduction threshold. But it's really that I played the 90 through that t d h headphone, and I'm getting vibrations through the skull, which are 90 minus 40, which are 50. And they're being heard on on this side because that's the threshold on that side. Okay. So the 50 is leaking over. So whenever I'm if I'm playing 90, so by the time I play 90, 50 is leaking over. Right? If I'm playing a 100, 60 is leaking over. But as soon as I get to 90, there's enough leaking over that they hear it. Because 90, there's 50 leaking over and 50 is what they hear. That's the threshold. That's on that side. That does that make sense? It's tricky. Right? It's because I think I'm testing this side, but the sound I'm playing to this side, some of it will leak over. And for t d h headphones, it's always whatever I'm presenting minus 40. Yeah. So if you played 80 on that side where you played 90 instead, would they not hear it? Because it's 50 on that side. Yeah. It needs to be 50. Exactly. So if I play 80 here, because there's 40 dB into aural attenuation, then 80 minus 40 is 40. That means it's 40 dB creeping across. Getting over here. Do do do do to the other copria. And it's below threshold. So you don't hear it. Right? But once I get up to 90, 9 b minus 40 is now 50. It's now hitting the threshold on that other side. Yeah. So when you test the masked air conduction threshold, you'll be able to tell that it's a dead ear? Like, it's a throat hearing? Yeah. That no measurable hearing. Right. So with yeah. We won't get into the all the procedures of masking, but masking will end up putting some noise into that better ear. So I'll tell the person, alright, you're now gonna hear some some wind kind of sounds like in in your better ear and you still have to listen to the beep. So I'm gonna try to cover up that ear. I'm gonna, like, raise its threshold to 60, for instance, by by putting some noise in there. And just, you know, without getting all the details, but just to kind of, explain how this works. So if I raised the threshold in this year, the better year to 60, what would happen now in this year? Do I still measure a threshold at 90? No. I'd have to go to where? A 100. Right? Because a 100 minus 40 is now 60. So I raised the threshold on that side and it changed the threshold I'm measuring over here. And that's how I know that they were cross hearing it. Right? So masking is the art of sort of doing that of and figuring out when I can raise the threshold over here and not doesn't change anything over here and say, ah, I found a true threshold in that ear. So that's that's kind of how it works. Alright. We'll go through some more examples. We have some more examples in a couple slides. This is just it's pulling out the oh, yeah. Sorry. So is the masking just playing a sound that's louder than the threshold in your ear? Basically. Yeah. We raises the virtual because the way sound matches masking is That's exactly it. Yeah. So masking is always it's always noise, but it's we're playing it's always above the threshold in the better ear. Yeah. To raise it. Yeah. That's that's right. So this is just kind of the equation in a nutshell what we said. So if the input to the test ear minus the intraoral attenuation. Right? Like because that's what leaks over. If it's below the threshold on the other side, they won't hear it on that side. But if it's at or above the threshold on the other side, they'll hear it on the other side. Right? So that's when I have cross hearing. So it's when you have an asymmetry in threshold that you need to do masking. Or when you're testing with what transducer? The bone oscillator. Right? Because bone oscillator, you've got no intra attenuation. So it's automatically going to both ears. You have to use masking all the time with both. So for the audiologists in the room, unless you have a job that's not in the clinic, you'll be doing masking every day of your life. It becomes it's not hard. It becomes very it's like driving a stick shift. It just comes out of you automatically. Even pre coffee in the morning, you just don't know how to do it. Right? Yeah. Alright. So whenever the input to the test ear, the ear you're testing, minus the intraoral attenuation, is greater than the threshold on the other side, which typically only happens when there's an asymmetry. They're gonna cross here. Or if you're testing with the bone conduction, bone oscillator, because it's minus 0. Right? So even if you're symmetric with the bone oscillator, you're gonna have to you're gonna have to do it. K. So how much leaks over? It's always the presentation level minus interaural attenuation. That's how much crossover you have. Okay. And crossover is always there. What we need to be able to look out for is the potential for cross hearing. Okay? There are 3 things this depends on. 1 is the transducer, which we've already talked about. Right? Which earphone or device I'm using? Transducer. So bone oscillator has 0. We know with TDH headphones, you've got 40. With insert phones, you've got 50. It's written on a future slide, but transducer matters. Also depends on frequency. So it's different at different frequencies. We're kind of ignoring that for the class to keep it simple. We're just saying 40 across all frequencies for t b h, 50 for insert. Otherwise, it's a lot of memorization. But audiologists will sometimes have a little chart posted so they can look at the individual frequencies. But for class, we'll just use a a flat number. Make it simple. It's close enough. And individual skulls. Everyone's different. K. So we assume the minimum. We assume those those numbers for class, but, individual differences in practice matter. It's a d in individual. Alright. So we don't know what the individual intraoral attenuation, IA, is for our client. So we assume the minimum one that's been recorded in studies, which is 40 dB for tDH and 50 dB for ER 3 for the inserts. Okay. Alright. Let's do another example with with, picture here. So let's say my the threshold presentation level or the threshold I'm measuring, let's say, in this ear is 50. So I'm getting a threshold at 50 dB HL. K? How much is getting let's assume there's no conductive loss. How much is getting to the cochlea on that side via air conduction? 50. 50. Right? Because it's no conductive loss. So 50 is getting to the cochlea via air conduction on that side. So let's say mountain reaching left cochlea is 50. K? How much with tDH headphones what level of sound am I getting through bone vibration? I think I heard it. 10. Right? Because 50 minus 40. So 10. So how much is reaching the right cochlea? 10. 10 dB HL. K. So we're always think about when you're presenting a level, how much might be getting to the other side. So when would cross hearing be an issue? If I'm measuring a 50 dB threshold here, cross hearing would be an issue if the threshold on this side is 10 dB or better. Right? Because I could have they could have heard it over there. The threshold that we hear was 20. They can't hear 10, so I'm fine. But if the threshold here was 10 and I'm measuring 50 on this side, it's possible they're hearing it over here. Right? So how much asymmetry is that? 50 and 10. 40. Right? So if I have 40 dB asymmetry if I measure a 40 dB asymmetry in thresholds with TDH headphones, I could have cross earring. Right? Because that's my intraoral attenuation. If I measured 10 on this side and I'm measuring 50 on that side, it's possible that that 50 I'm measuring over here is being heard over here. So that might not be real. It's one of the reasons why we always do the better ear first. Because we wanna know where this becomes a problem. Right? We always test it. And again, if they don't know what the better ear is, they're probably pretty symmetrical. Right? But if someone has a significant asymmetry, they'll tell you, oh, yeah. My right ear is better. So you can test that one first. Yep. Do you always start masking higher? No. Like an example or Yeah. So we always we always do better ear first. So in this case, we would have, like, measured that it found out it was 10 dB on this side. And then I'm just and I'm not asking yet and just doing my thing. And then as I'm measuring threshold on this side, I'm like going up and up and up. And it's like, oh, it's 50 over here. Right? And at this moment, as soon as I say, oh, it's 50, That's 40 dB asymmetry. I have to mask. And typically, in this case, I would immediately stop and tell the person, alright, you're gonna hear a little bit of noise. We're gonna keep you know, just explain it and you turn on the masker and you retest this threshold. How do you know that, like, cross over here and affect the pen or the threshold on the other side? Like, what how would I know that, like, they are hearing it over here? Like, if you knew that the threshold was pen Yeah. When you were measuring that, then how Well, so, like, if I test the it'll never go the other way. Right? Like, because see if someone has Yeah. Like, as long as you do the better your first, you're always okay. Because if it was if I went the opposite way, right, and tested this year, poor year first, I wouldn't know. And then as I did the better year, I'd be like, oh, what I measured on the other side might not be legit. Then I have to split it. Yeah. So how do you kind of tell, like, if you're not masking and let's say they don't like, do you have to ask them to kind of say when they hear it on the opposite side or how do you technically tell that they're hearing it on the other side if they don't really say anything? Sometimes, like, we usually don't. Like, some you can say, are you hearing it on the Yeah. Other side. Usually, as soon as you as soon as there's that much difference. So if I measure so if their one year was 10 and I measured a threshold over here of 30, I'm not worried at all. Right? But as soon as with the threshold I measure on this side is 40 dB worse than threshold I measured on that side. As soon as that happens, I just mask automatically. Right? That's why I just I just go in and and, like, I tell the person, of course. And then and then do the masking. Thing. So I don't know that they're hearing on the other side. Chances are, in practice, a lot of people have more than 40 d 40 dB intraoral attenuation. So chances are, that really is 50 on that side. So this is technically the bad year? We had already measured the good year? You always measure the gap. Okay. And we always, always, always, always measure the better ear first. So when you're starting the test, you ask the person, unless you know from the file, you know, which is your better ear. And we always start with the better ear. The only again, the only time we wouldn't is if they don't know which is the better ear, then just start with with whatever ear you want. But if they don't know what the better ear is, they're probably pretty symmetrical, so it's not an issue. It's use usually, if there's enough asymmetry for masking to be required, they'll know. Like, you know, there are situations where the person can't speak to you for language issues or other cognitive issues, whatever. You know, where you will end up doing the poor ear first. It just means you have to do more. You have to go back and mask later. Yeah. I was just gonna ask, why wouldn't you just start with masking? You could, in theory, start with masking all the time. It's just more time consuming. So getting, to find a mass threshold, you're doing a lot more steps. It's like you're doing a bunch of hearing tests all over that. Like, so if I'm finding 1 threshold, you know, it's down 10, up 5 to get a threshold. Then when I mask, you typically will do multiple masking levels. So you're getting a threshold and then you're moving the masker and you're getting a threshold again and moving the masker and getting it. It's just that it's a lot longer. Yeah. So we only mask when we need to. Where you run into it a lot if you're doing, a lot of bone conduction. Lots of people with complex situations. The the most common is people who are seeing an otologist often have a lot of complex conductive things going on and you have to mask a lot. So you just yeah. It just takes more time. So you get really fast at it. But, if we don't have to, we don't because it saves time. No? K. Let's take a break, and then we'll come back and finish up with math and brief questions. Right now. Sorry. Alright. Yeah. I know. That wasn't you I don't wanna rush to it because you guys you wanna understand. You might need like, it's it is a topic where so I suppose you might wanna sit with it a bit and try a few things. Like, it's oftentimes, you know, I'm I'm not great listening to things. I kinda sit down after and read it and draw it out and I figure, you know, so everyone's different. If you're really struggling and after you've sat with it and looked at the chapter and stuff, you don't get it, like, talk to me or Madeline. It's, you know, or other people. Like, it'll eventually click. It's not that bad. Yeah. Back to the masking. Sure. Do you have to change it for, like, every frequency range? Or can you just have, like, a set broad kind of situation? Oh, good question. Like, the masker itself? Do you have to check yeah. So the audiometer will choose the right masker for what you're testing. They're all programmed like that now. So if I'm testing, a 1000 hertz, it'll automatically have set up for me a 1000 hertz narrowband masking noise in channel 2. So I'll have to, as an audiologist, I'll have to turn on the masker and adjust the level. Like, there's a procedure to it. But, it'll be set up to give me the right masker. It's like having a little assistant for you. Or if I'm testing, like, doing speech tests, my channel 2 will automatically turn on with speech noise for masking speech. Like, it'll be set up with the right kind of masking noise. But as the clinician, you're gonna have to do the work. So, like, not we're not this is, beyond what we have to know for class, but just to kind of give an example. So if you want to like for this situation here, where I'm worried that there might be some cross hearing, I would turn on my masker on this non test side, on my channel 2. And I would first I probably turn it on at 20 which would should shift threshold in this ear. Right? Because it was 10. If I put a masker on it'll shift threshold. And then I'll retest threshold over there. And if threshold, doesn't change, I'm going to raise my master again and do that again just to confirm that it doesn't change. If threshold does change there, I'm still gonna raise my master here. Like, you do a kind of a dance with the levels to make sure that what you're getting over there is real. We and we won't go into all those steps because that's just too much. Like it's it'll be another class or 2 which is beyond what we need for this class. If you're on the audio side, we will get into it. It is written out in the chapter. It's not super hard, but that's next year. We don't do that till year 2. It isn't super hard. So if you wanna read ahead, if you're interested, go ahead. But like to to properly go through and take the time would be probably another class or class and a half, which we don't have time for really in this. Yeah. Yeah. We will go we are staying with masking a bit more though. So we are gonna go through some more stuff today. Just not that not the procedures. We'll leave the procedures off. I wanna do a couple more examples. This is essentially the same picture we are looking at. But let's imagine a situation where this person has a 40 dB conductor box. Okay? So let's just go through the numbers again just as an example. And let's say, again, I get a threshold of 50, 50 dB HL on this side. Okay. How much does the bone vibrate with TBH headphones? What am I getting in theory? 10. Right? Because I've got 40 dB 40 dB intraoral attenuation. Right? So the bone might be vibrating at 10. So how much how much am I getting to the opposite cochlear potentially? 10. Right? I could be getting 10 over here. Now I've got 40 dB conductive loss. So how much am I getting to my testier cochlea? 10. Just as an example, it starts to get a little more complicated when you throw conductive loss into the mix. Because now my conductive loss of 40 dB is the same as my intraoral attenuation. So when I present 50, I'm actually getting 10 to both sides. It gets trickier when you're, doing this in practice. Okay. All that matters as the clinician or, they're doing the test or as the person reading the audiogram is that if you see an asymmetry and they've used TDH headphones, if there's an asymmetry of at least 40 dB then those thresholds need to be masked. Okay? And we'll look at some audiograms but what actually matters is the threshold that was measured relative to the bone conduction thresholds on that other side. Because that's it's the cochlea that gets it. But we'll we'll go through some examples. Yep? Does the conductive loss ever contribute to the IA like It shouldn't. Yeah. Yeah. Yeah. So the conductive loss shouldn't do anything with the intraoral attenuation. Although, the intraoral attenuation limits how much conductive loss you can measure. Right? Because let's say this person in theory, let's say their middle ear was filled with concrete. So they would have like a 60 these are also dark, but like a 60 dB conductive loss. You could never measure it if they only have 40 dB intraoral attenuation. Because let's say this cochlea threshold was 10. Right? And let's say they had a 60 dB conductive loss. They shouldn't hear it until it's 70. Right? 10 plus 60 is 70. Right? So, but they're actually gonna hear it at 50 because at 50 dB, if they only have 40 dB intraoral attenuation, the head's already vibrating. That make sense? You'll hear it on the other side. And on this side. Because if the head's vibrating, both cochleas are gonna hear it. Yeah. Yeah. Yeah. So you can't your internal attenuation limits how much conductive loss you can actually record. Because that's the point at which the headphone is vibrating the skull. It's gonna get to the cochlear. Anyway yeah. Sorry. That's just extra. That's not yeah. Just because of the question, Mahesh. Yeah. Yeah. Exactly. Yeah. So if I had 20 30 dB of conductive loss, it'd be 20 getting to this one and 10 getting to that. That's exactly right. Yeah. These are good questions. Bone conduction, we assume 0 dB intraoral attenuation, which means if I put the bone oscillator on this test ear, I'm actually getting the same level to both of the cochleas. Now, in practice you often have a little tiny bit of intraoral attenuation for bone, especially in the high frequencies. But it varies by ear and it can be as low as 0. You know, so the reason I say that is, like, people will have a bone anchored hearing aid on both sides. It does stay a little bit. It doesn't always completely go over to the other side through bone vibration. But for some heads, at some frequencies, it goes over at 0. So we assume 0. We assume that what I'm presenting on here is getting both cochleas just as well. Okay? We always assume 0. So in practice it can be there can be some, but we assume 0. So if I'm presenting at 50 dB with my bone oscillator, how much does the bone vibrate? 50. How much is getting to the left cochlea? Right. And how much is getting to the right? 50. K. It's 50 it's 50 everywhere. We make that assumption. K. So we're gonna have to mask in that case. What I'm gonna have to do is put some masking noise into the ear I don't wanna test. Now, would I use another bone oscillator for my masking noise? No. Right? Because then the masking noise would go everywhere too. It doesn't help me at all. I have to use an air conduction earphone in the other ear so I can put some noise into just one ear. Let's look at some audiograms. This is a classic, there's no bone lines on here. Right? But you can see there's an obvious asymmetry. And so by the time let's say I got a threshold here at 90. I've already measured the better ear. I'll have those I'm gonna be in there if I I'll have those right ear thresholds already because I've got a better ear first. So let's say 2 I started probably 8,000. So I don't get a threshold until I'm at 95. And I know it was 40. So that's greater than a 40 dB difference. I'm gonna have to mask. This could be the right ear responding because that minus interaural attenuation might have been hurt on the right side. Right? Same thing for all of these thresholds. They're high enough that even when I subtract intraoral attenuation, it could have been audible on the other side. Now there's more than a 40 dB gap, but in remember, individuals all have slightly different intraoral attenuations. I don't know what that is. I just forteens the the smallest one. Right? So any of these could have been heard in the right ear. So this airline, if you're reading this audiogram, you don't know this is meaningless almost. All you know that hearing in that ear is there or farther down. Right? So it's not better than that. It could be a it could be a dead ear. It could be no measurable hearing. That could be the right ear responding. Yeah. Would it be safe ish to say that, like, if the bottom one followed the exact same pattern as the other one that there's a very good chance? It it yeah. Like, you don't know because it could you don't if it follows the same pattern, it it doesn't have to be cross hearing. But it does suggest it. We call this often a shadow curve because it's like the same rough shape. The internal attenuation can vary across frequencies. So it's not always gonna be like the exact it won't be the exact same pattern. I've kind of made it more similar than it usually is but we call it a shadow curve, like a lower threshold. Yeah. Yeah. It's actually if you had normal hearing on one side and you've got no thresholds on the other side at all, the person never heard it on the other side, what what would that actually suggest? Let's say their let's say their left ear came out 0 across the board. Perfectly average hearing. And then I tested the right ear, and they didn't hear it at all at any level. Like, there's something wrong with the cochlear app itself? I wouldn't even go farther. So I like that. Machine just was not Yeah. Yeah. It's possible that you've made a big mistake and you didn't turn it on. Yes. Any other any other? These are good. I think they lie I think they're lying to me. I think this is malingering because it should even if the cochlea is completely nonfunctional, at some point that should be crossover and be heard on the other side. They should be hearing something. Right? For whatever transducer I'm using, even an insert phone, you can get 70 dB interaural attenuation with those sometimes. They're gonna hear it at some level. They're gonna because it's gonna cross over. Right? So with sound, I can't get it I can't go beyond the limits of my audiometer without getting some hearing on that side. So if if they didn't hear it at all, sign of malingering. That they're pretending to have a hearing loss in one ear and just saying I'm not gonna hear anything in that side. Makes sense? Yeah. It's actually it's actually one of the signs of someone faking hearing loss that they would, which which does happen. We'll talk about that in in couple of weeks. Alright. That was a tricky one. Problem audiograms. So is it possible that those left ear thresholds were heard on the right? Yeah. Right? I have at least a 4 d 4 d dB difference between those thresholds. Okay. So if the person if you're doing the hearing test was with TBH headphones, you're looking for 40 dB difference, between them. Now, another question. Are you guys with me on that? Right? That this could be can we get all the right ear, so I'm gonna have put some masking noise into the right side and do some masking stuff. And then once I've done that, this is the important part for reading the audiogram. Once I have masked thresholds, these would be boxes. And then you can trust those. Those are true masked left ear thresholds. So you're looking, when you see an asymmetry like this, because sometimes people go to places to get audiograms done where it's not someone who should be doing audiograms. And they might say this is what they gave me. So it looks like I have a moderately severe hearing loss in my left ear. They probably wouldn't know the term for it. But as a professional you'd say, we actually don't know what your hearing is in the left ear. Like, we we really don't know. We just know it's it seems to be lower than the right ear. But it's possible there's no measurable hearing on that side. You have to you have to do the test right. The bone thresholds were done on the left side. You can see these left, unmasked bone threshold, and they match pretty closely to the air threshold on this side. But remember, bone thresholds just tell you the better ear. Right? So it's a half decent chance that it's just the right ear responding. So let's assume for a minute that we have masked these are masked air thresholds. Let's assume we can trust this. Just for a second. In that case, is that a conductive loss on the left? Sensory neural loss on the left? Can you tell? You can't tell. You have no idea. Right? Because when I do unmasked bone, it just the better cochlea gets it and responds. Right? So, obviously, one cochlea can hear pretty well. The right ear hears pretty well. So I, you know, that could have been the right ear. Could have been the left ear. I have no idea. I have to do masked bone to know what the left ear thresholds are. They could be down here, in which case it's a sensory neural loss. It could be up where the right ear is, in which case this is all conductive. It could be in between. It could be next. No idea. So if there's an air mass came, it has to happen first