Module 4

Question 1

Binaural vs Bilateral

Answer 1

-Binaural/monaural is referencing the auditory system
-Bilateral/unilateral is referencing the hearing aids themselves

Question 2

What are the benefits of hearing with both ears? (8 things)

Answer 2

-Reduction of the head-shadow effect: decrease in SPL especially in the high frequencies when sound is presented to the contralateral side of the skull
-Squelch Effect: the ability of the auditory to combine information from both ears in order to distinguish speech from noise
-Binaural summation of loudness: gain of 3-6 dB
-Improved sound localization: the ability to locate sound
-Redundancy: the brain having essentially two chances of extracting correct information
-Greater general ease of listening/balance
-Reduced risk of late-onset auditory deprivation in unaided ear
-Tinnitus suppression

Question 3

Unaided ear effect

Answer 3

-Auditory deprivation of an unaided ear manifests as a decrease in WRS

Question 4

Acclimization

Answer 4

-Hearing aids may be capable of reorganizing the CNS to help improve WRS

Question 5

Why might someone with hearing loss in both ears choose one aid?

Answer 5

-Financial resources
-Personal choices
-Expectations/biases prior to coming to appointment

Question 6

When would you only suggest one aid?

Answer 6

-One ear is unaidable (medically or audiologically)
-Binaural interference

Question 7

What is binaural interference?

Answer 7

-Seen in degraded performance of WRS
-When the performance of the poor ear degrades the performance of the better ear
-Prevalence of binaural interference may be between 8-10% of the elderly population

Question 8

What are the 7 guidelines for unilateral hearing aid fittings?

Answer 8

-Fit the ear with the best WRS
-Fit the ear with the flattest audiometric configuration
-Fit the ear with the widest dynamic range
-If the thresholds are 45 dB or worse bilaterally, fit the better ear
-If the better ear, unaided, is able to contribute to speech intelligibility, fit the poorer ear
-If thresholds and WRS are equal, fit the side that the patient can physically place hearing aid on
-If thresholds and WRS are equal, fit the side that the patient has a preference to use (examples of workplace, or phone/headset use)

Question 9

If no clear differences/preferences exist for which ear to fit, which ear should you fit?

Answer 9

The right ear should be fit first because there’s a right ear advantage due to information crossing to the left side immediately (where the language centres are stored)

Question 10

How recent was the “unilateral is okay” belief upheld?

Answer 10

1970s