[Elecraft] [K3] Hearing aids, meet K3

[Ian White]

Jim K9YC wrote:

>On 8/8/2013 6:19 AM, Bob W7AVK wrote:
>> Most of the recent Hearing Aids have something called T Coil or
>> similar feature.  Very popular in Europe where folks gather like
>> churches, etc. its essentially an inductive pickup.
>
>Yes, it is, but it has never gained traction in the US, where virtually
all
>systems for the hearing impaired use RF or infrared. I've used both
>successfully in some pretty big spaces, but prefer IR for most venues.
>
The T-coil system works well in large spaces that have poor acoustics,
and also for closed-front service counters in Banks (especially if there
is a lot of noise on the customer side). In large spaces I sometimes use
one hearing aid on the T-coil setting while the other is receiving the
room in the normal way. This gives very useful "diversity reception".
When listening to a single person speaking, the T-coil system often
gives the more intelligible signal because it receives a direct feed
from the podium or lapel microphone, unaffected by room acoustics.

>The Achilles Heel of these systems is stray magnetic fields, which can
add 60
>Hz hum to your hearing aid.

Further problems arise from the non-uniform magnetic field from the
large induction loop. Listeners sometimes have to orient their heads in
odd-looking ways to achieve a usable signal, while in high-signal areas
there is also a risk of unexpected feedback from musical instruments
that have magnetic pickups. 


73 from Ian GM3SEK