Hearing Aids Exam 3: RECDs and Real Ear

Questions and Answers

What is the pressure method?

What is the substitution method?

What does REDD stand for?

Real ear to dial difference

How is the real ear saturation response defined?

LDLs to reference with MPO and audio scan calculations. Signup and view all the answers

What does speech mapping concepts involve?

Audioscan's proprietary REAR using speech mapping. Signup and view all the answers

What is a coupler?

A small cavity that connects the hearing aid sound outlet to a measurement microphone. Signup and view all the answers

What does RECD stand for?

Real Ear to Coupler Difference. Signup and view all the answers

What test box measurements are taken to check a hearing aid's operation?

Distortion, internal noise, and response to magnetic fields. Signup and view all the answers

What curve is typically measured in test-box to represent a hearing aid's maximum output?

The curve of output versus frequency measured with a 90 dB SPL pure tone level input. Signup and view all the answers

What does REAR mean?

Real Ear Aided Response. Signup and view all the answers

What does REAG mean?

Real Ear Aided Gain. Signup and view all the answers

What is REIG?

Real Ear Insertion Gain. Signup and view all the answers

Why is insertion gain different from coupler gain?

Due to resonance effects in the unaided ear forming a baseline for the insertion gain measurement. Signup and view all the answers

What factors can lead to incorrect measurement of real-ear gain?

Incorrect positioning of the probe, squashing of the probe, blockage by cerumen, background noise, hearing aid saturation. Signup and view all the answers

When does feedback oscillation occur?

When amplification from the microphone to the receiver is greater than the attenuation of sound leaking back to the input. Signup and view all the answers

Describe the HA1 coupler.

It has no ear mold simulator and is used for ITE and ITC aids. Signup and view all the answers

Describe the HA2 coupler.

It includes an ear mold simulator, typically used for BTE hearing aids. Signup and view all the answers

List ways 2cc couplers and ear simulators can produce inaccurate results.

Poor sealing of ITE/CIC aids, stiffness of BTE tubing, worn o-rings, blocked pressure equalization holes. Signup and view all the answers

What is functional gain?

The difference between aided and unaided thresholds. Signup and view all the answers

What are in-situ measures?

Measurements taken with hearing aids in place in the person's ear. Signup and view all the answers

What does REUR stand for?

Real Ear Unaided Response. Signup and view all the answers

What does REUG refer to?

Real Ear Unaided Gain. Signup and view all the answers

What is REIR?

Real Ear Insertion Response. Signup and view all the answers

What is REOR?

Real Ear Occluded Response. Signup and view all the answers

What is speech mapping?

A method of doing REAR. Signup and view all the answers

What happens when REUR equals REOR?

You have a completely open fit. Signup and view all the answers

If the acronym ends in 'R', what does it mean?

Output Signup and view all the answers

What happens if you choose unilateral/bilateral inappropriately?

Can over/undershoot targets Signup and view all the answers

What do you do if you are undershooting high targets?

Check probe placement. Signup and view all the answers

What is REDD?

Real Ear to Dial Differences. Signup and view all the answers

What are the two main concepts when prescribing amplification?

Maximize speech intelligibility and ensure sounds are audible but comfortable. Signup and view all the answers

When prescribing gain, what should you consider?

Gender differences, age, prior hearing aid experience, and sound fitting approaches. Signup and view all the answers

What is linear processing?

The same gain-frequency curve for all input levels until high enough output levels cause limiting. Signup and view all the answers

What is non-linear processing?

Specifying gain-frequency response for several input levels. Signup and view all the answers

What is expansion in hearing aids?

As input level goes down, so does gain, to minimize/eliminate steady-state noise. Signup and view all the answers

What is WDRC?

Wide Dynamic Range Compression. Signup and view all the answers

What is output limiting?

It creates a max level for output, resulting in high compression ratios. Signup and view all the answers

What is peak clipping?

An output limiting function that can cause distortion. Signup and view all the answers

Describe mirroring the audiogram.

Gain is added based on subtracting 15 from each threshold where there is hearing loss. Signup and view all the answers

Describe the half gain rule.

It over amplifies low frequencies, potentially exceeding LDLs. Signup and view all the answers

What is the historical context of hearing loss amplification?

Studies from the 1980s indicated most people with hearing loss have mild to moderate levels. Signup and view all the answers

What prescriptions are available for non-linear processing?

DSI I/O, IHAFF, NAL-NL1, DSL 5, NAL-NL2. Signup and view all the answers

What does DSL I/O stand for?

Desired Sensation Level Input/Output. Signup and view all the answers

Describe NAL.

National Acoustics Laboratory, focusing on maximizing speech signals. Signup and view all the answers

Describe DSL 5.

Dynamic Sensation Level tailored for children and includes advancements in fitting practices. Signup and view all the answers

Study Notes

Hearing Aids: Key Concepts and Measurements

Coupler: A small cavity connecting the hearing aid sound outlet to a measurement microphone.
RECD (Real Ear to Coupler Difference): Canal SPL minus Coupler SPL; crucial for infants due to differing ear canal sizes.
Test-box Measurements: Include checks for distortion, internal noise, and response to magnetic fields to ensure hearing aids meet specifications.
Output Frequency Curve: Measured with a 90 dBSPL pure tone input to determine the maximum output capability of a hearing aid.
REAR (Real Ear Aided Response): Sound level in the patient’s ear canal, derived from coupler response plus several factors including RECDs and vent effects.
REAG (Real Ear Aided Gain): Difference between sound level in the ear canal and the input level near the patient; calculated using coupler gain and other effects.
REIG (Real Ear Insertion Gain): Level of sound in the ear canal with hearing aid minus level without; calculated as REAR minus REUR.
Insertion Gain vs. Coupler Gain: Insertion gain is impacted by the resonance effects of the unaided ear, forming a baseline for measurement.
Factors Affecting Real-Ear Gain Measurement: Probe positioning errors, probe blockage, background noise, and hearing aid saturation can lead to inaccurate results.
Feedback Oscillation: Occurs when amplification exceeds the attenuation of sound leaking from the output back to the input of the hearing aid.
HA1 Coupler: Used for ITE and ITC hearing aids; connects via putty, suitable for certain BTEs without ear molds.
HA2 Coupler: Includes an ear mold simulator, connects to BTEs, and is used primarily for traditional BTE fittings.
2cc Couplers and Ear Simulators: Can produce inaccuracies due to poor sealing or wear; Zwislocki coupler simulates average SPL with aid inserted.
Omnidirectional Mic Testing: Important to maintain proximity between control mic and HA mic to avoid acoustical shadowing.
Directional Mic Testing: Requires sound from the loudspeaker to hit the hearing aid at the appropriate angle as when worn.
Functional Gain: The difference between aided and unaided thresholds, verified through sound booth testing.
In-situ Measures: Measurements taken with hearing aids in place within a person's ear for accuracy.
REUR (Real Ear Unaided Response): Measurement of ear response with the probe mic only inserted.
Speech Mapping: A method to visualize REAR, with output measured on SPL y-axis; assists in fitting adjustments.
Complications with Fits: Choosing unilateral or bilateral fittings improperly can lead to overshooting or undershooting targets.
Amplification Goals: Maximize speech intelligibility and ensure sounds are audible yet comfortable.
Linear vs Non-linear Processing: Linear processing uses the same gain curve for all inputs, while non-linear processing specifies varied gain responses for different input levels.
Wide Dynamic Range Compression (WDRC): Fits inputs into a smaller dynamic range and broadens overall dynamic range.
Peak Clipping: A form of output limiting causing distortion, it can exceed the output level of compression limiting.
NAL and POGO Prescriptions: These frameworks guide amplification practices based on speech intelligibility and specific hearing losses.
DSL Versions: Over time, these have evolved to cater to both adult and pediatric use, incorporating unique adjustments based on trends in audiology.
Importance of Test Box Measurements: Essential for assessing the performance of hearing aids when patient reports indicate issues; a standardized approach helps maintain quality and function verification.
REDD (Real Ear to Dial Difference): Measures the discrepancy between received transducer output and what reaches the eardrum.
Real Ear Saturation Response: Measured using LDL for reference, helps determine the maximum output level of hearing aids under specified conditions.

These notes highlight the mechanisms and considerations involved in hearing aid fittings and testing, providing a framework for understanding the various concepts essential for audiologists and hearing care professionals.

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Description

Test your knowledge on hearing aids with this exam covering Real Ear to Coupler Differences (RECDs) and other essential concepts. Learn about couplers, test-box measurements, and their significance, especially in infants. Perfect for students in audiology or hearing science courses.