Midterm Study Guide PDF

General Be aware of, and be able to describe, the difference between task (how you elicit a sample) and measure (what property of the sample you are evaluating). (/ah/, how long they say it) You collect an instrumental measurement, but you can’t find reliable norms for that specific...

General Be aware of, and be able to describe, the difference between task (how you elicit a sample) and measure (what property of the sample you are evaluating). (/ah/, how long they say it) You collect an instrumental measurement, but you can’t find reliable norms for that specific measurement. How can you get value out of your instrumental measurements even if there are no good normative data for comparison? -establish a baseline and track changes over time -with enough measurements, create your own norms State three specific advantages that come from using instrumental as well as perceptual data collection in voice therapy. -instrumental: allows more precise evaluation of the problem, permits reliable documentation of outcomes, possible to collect data not available by other means -perceptual: assess voice by what is actually heard Midterm Review: Molecules are tight together at the peak, further apart at the trough Sound molecules don’t travel on their own; chain reaction; air molecules transmit the sound waveform: time (x axis), y axis is the changes in amplitude or pressure spectrum: frequency on x axis, amplitude on the y axis (no info about time) constructive interference: peak to peak (degrassi, ass to ass) if there's 100, 200, 300; the fundamental frequency would be 100 (greatest common denominator) harmonics are voice or larynx; formant frequencies or resonant frequencies are vocal tract Basic Acoustics Describe sound as a pressure wave using the terms compression/peak, rarefaction/trough. -sound can be represented as a longitudinal wave, which means that the displacement of the medium is in the same direction (or opposite) as the wave's direction of travel -sounds travels through air as a pressure wave creating alternate sections of compressions (on a waveform, these are the peaks), and rarefactions (on a waveform, the troughs) “When I produce a speech sound, air molecules from my lungs travel to your ear.” Is this statement accurate? Why or why not? -Due to elasticity, the molecules that transmit sound to the eardrum do not travel all the way from the sound source to your ear; But by passing the energy to many sets of molecules in succession, the wave as a whole can be transmitted over a long distance. Describe the oscillatory movement of particles in terms of the interaction of inertia and elastic forces. -When a force pushes on a group of air molecules, they gain inertia, and move closer to molecules next to them, creating an area of compression -pressure from the first group of molecules causes the second group to move away. -At the same time, the first group of molecules heads back toward its rest position due to elastic forces. -This creates a region of low pressure (rarefaction). 1 -the second group of molecules will press on molecules next to them, creating compression, then snap back, creating rarefaction. -In this way, alternating regions of high and low pressure radiate out from a sound source. What is the difference between transverse and longitudinal waves? A transverse wave is where the molecules move like an ocean wave. They go perpendicular to the wave. Whereas a longitudinal wave goes parallel to the wave. Sound travels like a longitudinal wave. What is the relationship between frequency and period? -period = time it takes to complete one full cycle of pressure changes (seconds per cycle -frequency = # of complete cycles occurring per unit of time (cycles per second = Hertz/Hz). -Frequency and period have a reciprocal relationship: F = 1/t ; t = 1/F Identify the perceptual counterpart of each of the following properties of sound waves: frequency, intensity/amplitude. Pitch is the perceptual part of frequency Loudness is the intensity/amplitude Define phase. Draw two waves that have the same amplitude and frequency but are 90 or 180 degrees out of phase. -Phase treats the wave cycle as a 360 degree rotation. The phase of the wave tells us where in its cycle the wave is at a given instant. Define constructive and destructive interference. Explain how the phase relationship of waves meeting each other leads to constructive or destructive interference. 2 If a region of compression (pressure peak) meets another region of compression, the result will be _constructive_________ interference. The amplitude of the resulting wave is __________. If a region of compression (pressure peak) meets a region of rarefaction, the result will be _destructive_________ interference. The amplitude of the resulting wave is _decreased_________. The type of interference between waves (constructive or destructive) depends on their relative ______phase____ (i.e., the relative timing of pressure peaks and troughs). -If a peak meets a peak, the resulting wave has greater amplitude = constructive interference -If a trough meets a peak, the resulting wave has lower amplitude = destructive interference Define: periodic wave, aperiodic wave. Explain how periodic and aperiodic waves are perceived in terms of sound quality. (Include speech sound examples.) A periodic wave has the same or identical repeating patterns of cycles versus the aperiodic wave has no repeating pattern. The perceptual qualities are that a periodic wave is like a vowel, a smooth sound whereas aperiodic is noise like /f/ or /s/. State the difference between simple and complex waveforms. Simple is like a tuning fork, a complex sound is like speech or noise, there are more than just one frequency What relationship must hold among the frequencies that make up a complex wave for the result to be a complex periodic wave? What do we call higher multiples of the fundamental frequency in a complex periodic waveform? The higher multiples are called the harmonics, the first one is called the fundamental frequency. Phonation and F0 Measures Describe how muscular, elastic, and aerodynamic forces interact in one cycle of vocal fold opening and closing. myoelastic aerodynamic theory of phonation myo-muscle force elastic tissue elasticity aerodynamic air pressures and flows First the vocal folds are adducted by muscular action 3 (lateral crico-arytenoid, interarytenoid muscles) Then subglottal pressure builds up in the space beneath the vocal folds Glottis is the opening between the vocal folds. Eventually this pressure blows the vocal folds apart and air rushes through This burst of air sets air in the vocal tract into vibration, creating sound What is the Bernoulli principle, and how does it relate to phonation? air flowing through the glottis to become negative in pressure; High-velocity flow of air creates negative pressure that sucks the VF back together as the velocity increases, the pressure decreases faster that something moves, the lower the pressure as air passes through the vocal folds, it speeds up and allows for decrease in pressure for vocal folds to close What properties of the vocal folds determine the rate at which they vibrate? -rate of vocal fold vibration depends on the mass and tension, and length of the folds -Larger vocal folds vibrate more slowly -Greater tension causes the vocal folds to vibrate faster -long vocal folds oscillate at a slower rate than short ones You should have a general sense of what would be a plausible rate of vocal fold vibration for (a) a child, (b) an adult woman, (c) an adult man, (d) an adult with a non-binary gender presentation. -Child F0 = 250-300Hz, Adult Female F0 = 180-220 Hz, Adult Male F0 = 100-140 Hz Non Binary: 145-175Hz Briefly explain how our perceptual response or sensitivity to changes in the frequency of a sound changes between low frequencies and high frequencies. At higher frequencies, a larger change in frequency is needed for an equal change in perceived pitch It is easier to perceive a difference at lower frequencies rather than at higher frequencies Name a scale that provides a perceptually based measure of pitch. Mel and Bark scales You should be able to read F0 using a Praat spectrogram with pitch tracking (blue line). If you suspected that Praat’s automatic pitch-tracking algorithm had made an error: o What setting(s) could you adjust to try to eliminate the error? ▪ change pitch floor and ceiling o How could you manually measure F0 to check the automatically calculated value? ▪ by doing cycles/seconds What is MPFR? Describe how you would elicit MPFR from a client. Name one clinical diagnosis that could cause a client to present with decreased MPFR. maximum phonational frequency range Typically measured from sustained vowel /ɑ/ Elicit client’s highest pitch, then lowest pitch; calculate MPFR as 4 the difference in between (in Hz or semitones) Decrease can be use to a mass on the folds or a weakness (nodule or polyp) What is SFF? Describe how you would measure a client’s SFF. What task would you use? Speaking fundamental frequency; Average SFF can be measured in multiple tasks. Sustained vowel phonation (typically /ɑ/) Passage reading Conversational speech sample Do both but when you are doing the connected speech make sure that it is long enough at least over 1 minute Amplitude and Intensity Measures What scale do we use to relate amplitude/intensity to our perception of loudness? The decibel scale; logarithmic, ratio-referenced Explain what it means for the decibel scale to be a ratio-referenced scale. Does the value 0 dB indicate the absence of any sound? If not, what does it indicate? It is because the ratio that it measures is the relationship between amp and intensity of two sounds. 0dB is the threshold of hearing it is not the absence of sound but the lowest we can hear Define: subglottal pressure; supraglottal pressure; intraoral pressure. What relationship must hold between subglottal and supraglottal pressure for the vocal folds to vibrate? Subglottal pressure must exceed supraglottal pressure for vocal folds to vibrate (this is the phonation threshold pressure or PTP) What type of speech sounds require a seal at the velopharyngeal port? Everything except for nasals; so mostly stops and fricatives What term do we use for the measure that is the amplitude/intensity equivalent of MPFR? 5 The dynamic range What is MPT? What would be a typical MPT for a nonpathological adult speaker? Maximum phonation time; 21-25 seconds best out of 3 times Does MPT distinguish between impairments in respiratory support versus laryngeal valving? -No, If MPT is decreased, further testing is necessary to determine the source of the problem (e.g. reduced lung volume, problems sustaining driving pressure, or inefficient glottal valving) Identify two factors that could contribute to variation in MPT among normal speakers. Reduced lung volume, problems sustaining driving pressure or inefficient glottal valving Explain how s/z ratio is intended to differentiate between respiratory and phonatory disorder. If both /s/ and /z/ have atypically short duration and ratio is around 1, it suggests that speaker has difficulty generating adequate driving force for speech (respiratory deficit). If s/z ratio is greater than 1 (/s/ is longer than /z/), it suggests that the speaker has difficulty in the laryngeal domain. Speaker can sustain a voiceless sound for a typical duration but has difficulty sustaining a voiced sound. It may point to a problem with laryngeal valving. Vocal folds do not close completely—air escapes during closed phase—speaker runs out of air faster What s/z ratio are normal speakers supposed to have, in theory? Around 1 What is an s/z ratio >1 thought to suggest? A vocal fold pathology What would you expect to observe for the s/z ratio in a patient with normal laryngeal valving but reduced respiratory support? Both /s/ and /z/ would be short Voice Registers and Voice Quality Measures Describe the human voice in terms of (a) periodicity, (b) complexity of the waveform. Complex and nearly periodic and has fundamental frequency and harmonics Given the frequency and amplitude of individual components, be able to represent a complex sound as a line spectrum. 6  Name three registers of vocal fold vibration. For each one, describe (a) the rate of vibration/F0; (b) the pattern of vocal fold vibration; (c) the subglottal pressure needed to drive phonation. 1. Modal voice register (normal vocal quality) regular speaking voice 2. Falsetto register (also called loft register) rate of vibration is high, pattern is less complex, higher subglottal pressure, vocal folds stretched 3. Pulse register (also called vocal/glottal fry or creaky voice) rate of vibration is low, vocal folds are slack and hang loosely together and lower subglottal pressure What is breathy voice quality? Describe it in terms of (a) its acoustic properties, (b) the configuration and movement of the vocal folds. -refers to voice produced with incomplete closure of the vocal folds - Vocal folds are close enough to vibrate, but a continuous stream of air can escape through opening in the folds during speech, Escaping air is audible as high-freq aperiodic noise Why is breathy voice considered an inefficient form of phonation? (Consider how measures such as Vocal folds are not completely closed; lots of air comes through. MPT might differ between a speaker with a breathy voice quality versus typical voice quality). -Cannot sustain phonation for as long as if airflow were valved efficiently (complete seal); Dynamic range is reduced - can't build up subglottal pressure; Pitch range also reduced. What is a rough/hoarse voice? Describe it in terms of (a) its acoustic properties, (b) the configuration and movement of the vocal folds. -Rough or hoarse voice refers to voice produced with aperiodic vibration of the vocal folds - may be caused by an asymmetry in the vocal folds, e.g. a mass on one vocal fold, Can also be caused by swelling of vocal folds, which disrupts the mucosal wave; Aperiodic vibration creates extraneous noise. Noise is at lower frequencies than the additive noise in breathy voice -Hoarse voice is sometimes used to refer to a voice quality that is simultaneously rough and breathy (not universal terms) Define (a) jitter, (b) shimmer. Why are these measures described as “perturbation” measures? Jitter: cycle-to-cycle variations/perturbations in frequency Shimmer: cycle-to-cycle variations/perturbations in amplitude What causes cycle-to-cycle changes in the waveform? Vocal folds may be slightly asymmetrical; one fold may have more mucus on it than the other, creating frequency irregularities Fluctuations in lung pressure may affect frequency or amplitude Air may become turbulent as it passes through the glottis What task (method of elicitation) should you use to collect jitter and shimmer measures? Sustained vowel /ah/ 7  What does CPP stand for? Identify three specific reasons that clinicians are advised to use CPP instead of perturbation measures such as jitter and shimmer. Cepstral peak prominence continuous speech, dysphonic speech, Can be used to analyze continuous speech Valid for voices with moderate to severe dysphonia, unlike perturbation measures Highly correlated with perceptual ratings of dysphonia severity Heman-Ackah et al. (2002); Awan & Roy (2005); Lowell et al. (2012); Awan et al. (2013) Discriminate dysphonic from normal voices with strong accuracy Define harmonics to noise ratio (HNR) Harmonics-to-noise ratio (HNR) Recall that a harmonic is a whole-number multiple of the fundamental frequency. Harmonics are the product of periodic vibration of the vocal folds. The human voice also features some aperiodic noise (irregular vibration, noise of air escaping). HNR compares the loudness of the harmonics of the vocal source vs. extraneous noise. Higher is better. It is usually reported in dB. Source: Horii & Fuller, 1990 For all voice quality measures (jitter, shimmer, HNR, CPP), be able to indicate if a higher or a lower value is expected for a typical versus disordered voice quality. If someone has a disordered quality you might see decreased everything but increased jitter and shimmer (because jitter and shimmer=bad) 8