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Masking Dilemma?

keskritt at SPRYNET.COM keskritt at SPRYNET.COM
Fri Oct 10 20:53:05 EST 1997


I agree with Bob Siegel...You should have a repeat audiogram done to determine 
your true bone levels.  It sounds like the Audiologist who conducted your 
assessment was using TDH style headphones (the ones that look like regular 
stereo headphones, only larger...)  When you use the TDH headphones, then the 
chances of running into a masking dilemma is much more likely, as interaural 
attenuation (IA) occurs around 45-50 dB HL.  In your case, the masking level 
needed to block out the nontest ear would be greater than the maximum IA using 
the TDH headphones.  As a result, the masking noise actually crosses over to the 
test ear through the bones of the skull, potentially making your true bone 
conduction levels look poorer than they are.

To eliminate the problems of the masking dilemma, testing should be conducted 
using ER-3A insert earphones.  These headphones are quite different than the 
standard TDH style...rather than having cups than fit over your ears, the 
inserts fit right into the ear canal using foam plugs that look similar to foam 
noise protection.  By using the inserts, the IA actually is greater (from 70+ dB 
HL), so often the masking dilemma is eliminated for most cases of moderate 
conductive hearing loss.

We use ER-3A inserts for all of our testing, and I have never come across a case 
of masking dilemma using this type of headphone...

Kimberly A. Eskritt

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