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Need advice on new aids

David Hotvet dahotvet at mmm.com
Tue Jan 16 10:57:41 EST 1996

lillqvis at cc.Helsinki.FI (Holger Lillqvist) wrote:

>Ward R Drennan commented on another posting:

>: >4) One of my few complaints about the T95 is the poor performance of the
>: >telecoil.  Are there any aids of that power level with a good telecoil?

>: I'm sure you can find something that will please you. 

>Hm, I wouldn't be that confident. In my experience, selecting a new aid
>has always been a rather frustrating affair exactly because most aids have
>poor telecoils. I can't understand how people manage at work - and at home
>too - without decent telecoils for phone talk. It seems to be no
>coincidence that the T95 was paired with a Widex in the other ear. For the
>last ten years I have also used Widex aids, and not least beacuse of the
>strong telecoil (and the practical MT -position, missing on many aids:
>when talking in the phone you hear if the doorbell is ringing, or somebody
>talking in the room).

>When do aid manufacturers learn to give this question serious attention?

Part of the problem is that there has been no direct comparison
between the microphone and telecoil inputs. Telecoil output is
measured at a single frequency within a loop with a known magnetic
field strength. There are many measures of acoustic performance:
frequency response, gain, etc. But the two have not been directly

There is hope for the future. A new ANSI standard for hearing aids is
due to be released this year that directly compares the telephone coil
sensitivity to the microphone, both under nominal operating
conditions. A new telephone simulator has been specified to better
emulate a regular telephone. Telecoil input frequency response will be
measured, as will the high frequency average gain. Additionally, a
difference rating will be show that compares the high frequency
average gain between the acoustic and magnetic (telecoil) inputs. A
very close match between the two will register as a 0. Under normal
conditions, this means that there will be little difference in
loudness when switching between the microphone and telecoil. 
This will be measured and shipped with all aids with a telecoil.

   Dave Hotvet                   Internet: dahotvet at mmm.com  
   3M Hearing Health             Phone:    612-733-6350 
   3M Center 260-6A-18           Fax:      612-736-3892   
   St. Paul, MN   55144-1000
 My opinions? Of course. 3M's?... Nope.
"Without deviation from the norm,there can be no progress"

Opinions expressed herein are my own and may not represent those of 3M.

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