Hearing Aids

[PaPaPeng]

There is a discussion in a disabilities support group about the latest
hearing aids having an induction loop and digital circuitry. Is
anyone familair with the technology innovations?

Two questions.
1. In what way will digital be better over analog? After all the
requirement is only to amplify sound, not process it - a case of
simplicity over complexity. Even if an analog hearing aid picks up
everything at a noisy cocktail party for example, the human brain is
still the best mechanism to filter out the extraneous noise.
2. What does the induction coil do in in the hearing aid. My guess is
that it allows an outside oscillator to induce a current in the
hearing aid thereby eliminate the need for an internal battery. Its
like the charger for miniature remote control cars at Radio Shack.

 

[colin]

There is a discussion in a disabilities support group about the latest
hearing aids having an induction loop and digital circuitry. Is
anyone familair with the technology innovations?

Two questions.
1. In what way will digital be better over analog? After all the
requirement is only to amplify sound, not process it - a case of
simplicity over complexity. Even if an analog hearing aid picks up
everything at a noisy cocktail party for example, the human brain is
still the best mechanism to filter out the extraneous noise.
2. What does the induction coil do in in the hearing aid. My guess is
that it allows an outside oscillator to induce a current in the
hearing aid thereby eliminate the need for an internal battery. Its
like the charger for miniature remote control cars at Radio Shack.

Im not 100% sure but I think the Induction loop is used to broadcast sound
to hearing aid users from say a speaker using a microphone. maybe telephones
too?

As for digital processing I heard this is claimed to allow much larger
volume amplification by dynamicaly altering the response to avoid feedback
noises. Im not sure if the technology even exists to distinguish wanted
noises from unwanted ones.

Colin =^.^=

 

[Joel Kolstad]

1. In what way will digital be better over analog? After all the
requirement is only to amplify sound, not process it - a case of
simplicity over complexity.

I know next to nothing about hearing impairments, but I'm fairly certain that
in many cases deafness occurs only over specific frequency range(s). That is,
the hearing loss is not just a "flat line" attenuation, but is a significant
function of frequency. As such, it's much easier to create an "inverse" gain
response with digital techniques that it is with analog.

Even if an analog hearing aid picks up
everything at a noisy cocktail party for example, the human brain is
still the best mechanism to filter out the extraneous noise.

That's pretty subjective. Radio operators use electronic filters all the time
to improve signal intelligibility, and although the "noise" coming over a
radio has a different distribution than the noise at a cocktail party, it's
not much of a leap to suggest that having the ability to filter a signal in
ways other than those that your brain alone provides is useful.

2. What does the induction coil do in in the hearing aid. My guess is
that it allows an outside oscillator to induce a current in the
hearing aid thereby eliminate the need for an internal battery. Its
like the charger for miniature remote control cars at Radio Shack.

I'm not certain, but besides providing power to an implanted receiver, I would
venture that it probably also transmits the audio itself.

---Joel Kolstad

 

[Steve]

1. In what way will digital be better over analog? After all the
requirement is only to amplify sound, not process it

Incorrect. The aid should amplify only those sound frequencies which
the ear is not hearing normally. Deafness is usually not a "linear"
problem, high frequency loss is common. Different patients may cut
off at different frequencies. A modern hearing test involves first
plotting the response of the ear across the whole of the normal audio
spectrum. A modern digital aid is then programmed by computer to
amplify frequencies where the ears respose is abnormally low. It
therefore is customisable for the individual patient. Indeed a
frequency plot and programming is done for each ear, left and right
sides may vary for the same patient. If you amplify all frequencies
equally you will just confuse the picture. My son for example has
severe high frequency loss, but normal low frequency hearing, straight
amplification of everything would not be a good thing in this
situation. Older analogue aids did have a configurable frequency
response curve, but it was not so customisable as with the digital
aids and computer s/w.

simplicity over complexity. Even if an analog hearing aid picks up
everything at a noisy cocktail party for example, the human brain is
still the best mechanism to filter out the extraneous noise.

Harder not easier though if you are being deafened by loud and
unneccesarily amplified low frequencies which the ear hears normally.

2. What does the induction coil do in in the hearing aid. My guess is
that it allows an outside oscillator to induce a current in the

Induction loops are a method of directly coupling audio to the aid,
hence avoiding the listener having potentially confusing background
sounds also amplified. Cinemas for example can transmit sound this
way if so equiped. Also telephones, whatever. The aid has a "T"
switch on it which switches over from normal microphone to loop input.

Steve

 

[Joerg]

Hello Colin,

Im not 100% sure but I think the Induction loop is used to broadcast sound
to hearing aid users from say a speaker using a microphone. maybe telephones
too?

Sometimes both, power transfer and signal transfer.

As for digital processing I heard this is claimed to allow much larger
volume amplification by dynamicaly altering the response to avoid feedback
noises. Im not sure if the technology even exists to distinguish wanted
noises from unwanted ones.

It does. There are filter algorithms and slopes that are next to
impossible in the analog world. It's tough to say that as an analog guy
but that's the way it is. Depending on the case and severity of hearing
loss such filtering must be quite intense. Also, it is much better
programmable for a custom solution than analog. Some applications such
as cochlear implants would be almost impossible in an analog fashion.

Then there are costly component tolerance issues which are eliminated in
a digital design.

Regards, Joerg

 

[Joerg]

Hello Steve,

Induction loops are a method of directly coupling audio to the aid,
hence avoiding the listener having potentially confusing background
sounds also amplified. Cinemas for example can transmit sound this
way if so equiped. Also telephones, whatever. The aid has a "T"
switch on it which switches over from normal microphone to loop input.

Is there a standard? This would be good for places like our church. We
have a radio wand system but have to hand out analog wands that just
feature a simple volume control. Plus they break all the time. I've got
one here right now where the potmeter became erratic. Again.

Regards, Joerg

 

[Jim Thompson]

Hello Steve,


Is there a standard? This would be good for places like our church. We
have a radio wand system but have to hand out analog wands that just
feature a simple volume control. Plus they break all the time. I've got
one here right now where the potmeter became erratic. Again.

Regards, Joerg

"Potmeter"?? What are you smoking at that church ?

...Jim Thompson

 

[Joerg]

Hello Jim,

"Potmeter"?? What are you smoking at that church ?

ROFL!

Ok, yes, we are in California but it doesn't go that far...

It's a drag. Much of that "professional" gear is easily repairable yet
often they won't ship you parts or require to send it in to a 'certified
repair facility', meaning lotsa $$$. We could somehow find that potmeter
but I bet then we'd have to do a minimum buy of a whole crate.

Regards, Joerg

 

[John Fields]

"Potmeter"?? What are you smoking at that church ?

 

[John Fields]

Hello Jim,


ROFL!

Ok, yes, we are in California but it doesn't go that far...

It's a drag.

---
In CA, I think that's called a "toke"
---

Much of that "professional" gear is easily repairable yet
often they won't ship you parts or require to send it in to a 'certified
repair facility', meaning lotsa $$$. We could somehow find that potmeter
but I bet then we'd have to do a minimum buy of a whole crate.

---
If you wanted to install an inductive system, I'll bet John Woodgate
could help you out since ISTR that he has some expertise in that
area.

Where is he, anyway?

Prob'ly got tired of the crap on this channel...

 

[Steve]

Hello Steve,


Is there a standard? This would be good for places like our church. We
have a radio wand system but have to hand out analog wands that just
feature a simple volume control. Plus they break all the time. I've got
one here right now where the potmeter became erratic. Again.

Regards, Joerg

Yes there does seem to be a standard, don't know the official name for
it. See the URL below. Places of worship are mentioned in the FAQ
here as a suitable application for the technology. There is a
standard symbol which can be displayed at sites where T loop is
available, which you might recognise, see:

http://www.hearingloop.org/fq_preferred.htm


Steve

 

[Joerg]

Hello John,


Hmm, never heard that before. Then again, I didn't grow up in CA. And I
didn't grow anything either

---
If you wanted to install an inductive system, I'll bet John Woodgate
could help you out since ISTR that he has some expertise in that
area.

Where is he, anyway?

Prob'ly got tired of the crap on this channel...

IIRC he signed off a while ago because of some job, I think. But it's
been a while.

Regards, Joerg

 

[Joerg]

Hello Steve,

Yes there does seem to be a standard, don't know the official name for
it. See the URL below. Places of worship are mentioned in the FAQ
here as a suitable application for the technology. There is a
standard symbol which can be displayed at sites where T loop is
available, which you might recognise, see:

http://www.hearingloop.org/fq_preferred.htm

Interesting, thanks! I had asked a few of our hearing impaired and none
had ever heard about such a system. Looks like it would be around $2k
for our size church if we do the install as volunteers. That's more than
the existing system but considering the convenience it would make sense.
As long as I can find out whether the majority has T-Loop enabled
hearing aids.

Regards, Joerg

 

[martin griffith]

---
In CA, I think that's called a "toke"
---


---
If you wanted to install an inductive system, I'll bet John Woodgate
could help you out since ISTR that he has some expertise in that
area.

Where is he, anyway?

dunno, miss his wit, He's one of the good guys here, along with Win
and Jim (ooops)


martin

 

[Spehro Pefhany]

Hello John,



Hmm, never heard that before. Then again, I didn't grow up in CA. And I
didn't grow anything either


IIRC he signed off a while ago because of some job, I think. But it's
been a while.

I have seen his cross-posts from sci.lang.translation recently, so it
wasn't entirely work-related...


Best regards,
Spehro Pefhany

 

[Jim Thompson]

I have seen his cross-posts from sci.lang.translation recently, so it
wasn't entirely work-related...


Best regards,
Spehro Pefhany

Well! There certainly hasn't been any requests for serious circuit
design help here in a very long time, so I guess I'll have to just
keep picking on leftist weenies :-(

...Jim Thompson

 

[Joel Kolstad]

Well! There certainly hasn't been any requests for serious circuit
design help here in a very long time, so I guess I'll have to just
keep picking on leftist weenies :-(

We're hoping you're going to start writing that book of yours, Jim.

 

[John Fields]

dunno, miss his wit, He's one of the good guys here, along with Win
and Jim (ooops)

---
So what am I, chopped liver?

Hundreds (maybe thousands) of _free_ designs which work, schematics
which are easy to read and build from and, since I don't blow my own
horn too often, anonymity, more or less.

Lucky me, I get to die as an unknown...

 

[Jim Thompson]

We're hoping you're going to start writing that book of yours, Jim.

Keep me loaded up with "exercises" and I'll start writing. Writing,
by itself, is terribly boring... after all it's an "I did that
already" task.

Reminds me, my wife is very active in charities and Girl Scouts.
Nearly 30 years ago I had a sculpted gold pendant made for her....

(o)
I
DID
THAT
ALREADY

(Except that "THAT" was properly half-spaced ;-)

...Jim Thompson

 

[Steve]

Interesting, thanks! I had asked a few of our hearing impaired and none
had ever heard about such a system. Looks like it would be around $2k
for our size church if we do the install as volunteers. That's more than
the existing system but considering the convenience it would make sense.
As long as I can find out whether the majority has T-Loop enabled
hearing aids.

Regards, Joerg

Seems as if there is more awareness of T-Loop here locally in the UK.
It's common to see the sign in banks for instance, as the teller has
to use a microphone to talk accross the security glazing. All the aids
son Tom has been supplied with have a T setting. Check out a major
player like Siemens if you need more detail on them

Steve