Masking Dilemma?

RSiegel663 rsiegel663 at aol.com
Thu Oct 9 23:24:26 EST 1997


>Subject: Masking Dilemma?
>From: ed.luczak at gsfc.nasa.gov (Ed Luczak)
>Date: Tue, Oct 7, 1997 21:17 EDT
>Message-id: <ed.luczak-0710972117210001 at eluczak.gsfc.nasa.gov>
>

Ed,  

Get another evaluation before you do anything.
how long has it been since your previous evaluation and where was it done?  
The dilemma is from overmasking.  The question is "can I apply enough masking
 by air conduction to keep the nontest ear busy to find out what the BC scores
 are in the test ear?".  When sounds get loud enough by air condiction , the
 skull begins to pass it through by Bone conduction and it masks( covers ) the
 test ear's function.

Using the Best bone results you have a conductive involvement and should be
 retested to determine if it is one or both ears.

e-mail if I can be of help.
Bob

>Can someone please explain the "Masking Dilemma", and how to best
>interpret audiological test results when this is experienced?
>
>My situation is as follows.  I have a hearing loss that has been diagnosed
>as otosclerosis, and underwent a right stapedectomy in 1976.  Although the
>surgery initally restored hearing, performance in the operated ear
>gradually deteriorated, and I now wear hearing aids in both ears. 
>Periodic audiological evaluations have shown air conduction losses in the
>50-65 dB range, and masked bone conduction losses in the 10-25 dB range in
>both ears.
>
>Last week I was tested by an audiologist I had not visited before.  The
>test results are summarized below (view with a monospace font!):
>
>               250   500  1000  2000  3000  4000  6000  8000
>
>Left
>AC              60    60   65    50    55    60    60    30
>BC-"BestBone"    0     0   20    20    10     5
>BC-Masked       20    25   30    50    40    45
>
>Right
>AC              50    45   50    60    65    70    70    55
>BC              (not recorded)
>BC-Masked       30    35   40    55    35    45
>
>The audiologist indicated that the test results exhibited the "Masking
>Dilemma", and explained the testing symptoms, but I'm still confused a
>bit.  She pointed out that the "BestBone" measurements indicate the
>sensorineural response of at least one, and possibly both of my ears. 
>However, because sound from the transducer placed on the bone behind one
>ear can propagate through the skull to the other ear, masking tests are
>performed to determine the sensorineural response of each ear
>individually. As shown above, the BC-Masked test results are 20-40 dB
>below the "BestBone", on both ears.  This seems to be a logical
>inconsistency (is this the dilemma?), because the BC tests indicate at
>least one ear with fairly good senso-neural performance, but the BC-Masked
>tests show two ears with sensorineural losses.  
>
>My concern in interpreting these results is two-fold:
>
>1. Hearing aid fitting - Is there a difference in specifying the best
>hearing aids for a patient having a sensorineural loss versus one with
>only a conductive loss?  The audiologist recommended that I consider new
>Resound hearing aids. The Resound web pages and brochures say that their
>patented amplification technology "specifically addresses the need to
>compenstate for the loudness sensitivity common in sensorineural hearing
>impairment."  My BC-Masked measurments indicate that this might be for
>me.  My BC-BestBone measurements indicate that at least one, and maybe
>both of my ears don't need this rather expensive technology.  How do I
>choose?
>
>2. Surgical options - In consulting with an ENT MD after the audiological
>test, he said that the BC-Masked results, especially in the 500-2000 Hz
>range, indicate that little improvement would result from stapes surgery,
>because much of my hearing loss is sensorineural.  But is it really?  Or
>are these important measurements incorrect, due to the "Masking Dilemma"?
>
>I'd appreciate any insight that anyone can share with me on this.  Thanks,
>
>--Ed Luczak
>
>-- 
>NASA/Goddard Space Flight Center
>
>The opinions expressed in the article above are not necessarily 
>those of NASA or any of its contractors.  The poster is respon-
>sible for the accuracy of the statements above.
>
>
>
>
>
>
>


Robert B. Siegel M.S. CCC-A, BC-HIS
Family Hearing Centers
2001 Lincoln Dr W.   Suite E
Marlton, NJ 08053-1531





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