Feedback Suppression

Dawna Lewis LEWIS at BoysTown.ORG
Tue Nov 14 14:46:31 EST 1995

>In article <484s49$4v8 at>, erc at (Eric Smith) says:
>>3.  Are there special earmolds available that solve the feedback
>>    problem even in the most difficult cases without causing more
>>    problems such as sore ears etc.?
>I would like to hear from others on this question.... I have seen comfort
>problems with a few patients using full-shell soft material molds...
>Can one control discomfort and feedback by moving to a harder material ??
>Jeff Sirianni     @(((<{
>University of Texas at Austin
>Communication Sciences and Disorders
>CMA, 2nd Floor Clinic
>Austin, TX  78712-1089
>sirianni at
>jgsaudio at
  At our facility we see primarily children and almost always use soft material
, especially for those with severe to profound losses.  The material of choice 
varies depending on the user.  Silicone materials have worked very well for us 
(we use Westone Labs for most molds and use their W-1 material quite a bit. 
Also, a number of staff members have had really good success with molds made
from their Aquanot material--it also allows for a great range of colors!). 
These materials are a problem sometimes on the very young because the tubelocks
used to hold the tube in place are so large in relation to the canal portion of
the mold that they tear through the material.  Also, they are very difficult to
modify due to the material.  We do have fewer complaints of discomfort with the
soft molds.
  We expect to replace earmolds fairly often, especially with the more severe 
losses because so many of our patients are growing.  We do attempt to get longer
canals whenever possible, extend tubing to the end of the canal if the patient 
can't use the high freq. info due to degree of hearing loss, etc.  We also have 
recommended ear level FM systems for a number of our patients with severe to
profound losses because their greatest needs were related to distance and noise.
In these instances, the separation of the mic and receiver eliminates the feed
back problem, at least in the FM mode.
  A number of the earmold companies advertise soft molds in a style that is like
a canal lock or half shell which they say prevents feedback as well as the full
shell molds.  We haven't had success with these with the young children, though.
  Even our adults usually prefer the soft molds in most cases.  The exception 
would be geriatric patients who sometimes have more difficulty manipulating the
soft molds for insertion and prefer hard materials.
  It seems to me I remember someone posting to this group earlier about the 
Patriot mold from All American Labs (i think).  That is supposed to be a very
comfortable soft mold that helps prevent feedback but I haven't had experience
with it.
  Hope this is helpful.

Dawna E. Lewis			e-mail address: lewis at
Clinical Audiologist
Boys Town Natl. Res. Hospital		phone:  402-498-6607
555 N. 30th Street			fax:  402-498-6638
Omaha, NE  68131

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