Amplified Telephones for the Hearing Impaired

[rotatepod]

I've purchased and returned several expensive amplified phones
for my dad. The last phone I returned cost almost $400.00. It had
three seperate tone or pitch adjustments. I asked (well, almost
forced) three people with normal hearing to try this phone. They
all agreed with me. This $400.00 box was a piece of junk.

I think I have the beginnings of a solution for my dad. He uses
IR cordless headphones so he can hear the TV without shattering
the windows! The solution starts by purchasing a full cup style
headset with a boom microphone element like this one:

http://www.officedepot.com/a/products/7 ... 0-headset/

I'm almost certain that by enclosing both ears with foam earcups
very little additional amplification will be needed.

To complete the last two pieces of the puzzle I need some help.

A small inline amplifier for headset is step two. I've seen many
cheap kits and a few ready built models. The final step is the
phone itself. Years ago I purchased an incredibly simple cordless
headset phone called the Bell Sonecor. It consisted of a small
rectangular box with a keypad. That's it! I used it several dozen
times when I had to make tech support calls and keep my hands free
for the mouse and keyboard. The sound quality was very good
for an early model cordless phone. I wish I could find something
that simple for my dad.

Whatever size jacks or plugs are needed should not be a problem.
There are adapters for almost any configuration.

To sum up, point me to a phone and amplifier that will work with
the headset and I'll start spending money. It's worth one last try,
before I call it quits.

[[ Why isn't my dad using hearing aids? He invested time and
money trying various hearing aids. If you read any of health
related forums, the list of people having trouble with hearing
aids is endless. Unless they fit perfectly you're constantly
tormented by high pitched feedback. Even when the fit is
good, the smallest amount of contamination can cause feedback.
Our former president, Ronald Reagan used hearing aids. All
presidents have a personal physician that are with them 24
hours a day. I always wondered if this guy spent a couple of
hours a day cleaning and adjusting Reagan's hearing aids! ]]

[Bigglez]

The solution starts by purchasing a full cup style
headset with a boom microphone element like this one:

I'm almost certain that by enclosing both ears with foam earcups
very little additional amplification will be needed.

I'm with you so far, but one detail needs to be reviewed.

A natural speaker hears themselves by two paths, one via
bone conduction and the other by "side-tone" where the
speaker's own voice leaks back to their own ears.

If you submerge your head in water (swimming pool for
example) you stop the acoustic side-tone and only have
bone conduction. On the other hand, if you record your
voice electronically (tape recorder) and play it back you
have side-tone only and no bone conduction. Most people
think they 'sound different' when recorded!

Your proposed project of fully immersed headphones
will require side tone to give the speaker a natural
acoustic feedback as they speak. It is by this method
that we adjust volume. Hard of hearing people often
shout as they can't easily hear their own output while
speaking.

Now to the meat of my post. You will need to add
side tone to your father's headset so he can hear himself
speak. The amount will depend upon his hearing loss.

I'd suggest that you buy the headset with boom mic
and rig it to give side tone. Have him wear it and see
if he is comfortable speaking and hearing others.
(I'll assume that wearing a headset is not an embarassment
for him - much like wearing glasses isn't for the visually
paired amongst us).

To create side tone for a non-deaf person requires a
small portion of mic audio to enter the ear audio. In your
father's case he may need a lot of side tone, and that
calls for amplification.

A kit built or utility battery-operated amplifier with
simple mixing of TV audio and mic side tone is required.

By getting him comfortable with the headset and TV
audio you are ready to introduce the phone part later.

I followed the link you supplied and the limited info doesn't
state if the headset has side tone, and another thing,
the electrical jack would need four conductors to have
common, mic, L, and R connections. Perhaps this isn't
what I think it is?

[jollyrgr]

There are a number of cordless phones on the market that have a headset jack on them. This accounts for both the interface to the phone and will produce a sidetone as needed. There are also corded phones "hands free" phones if you want to go corded. I think Radio Shack used to carry these in their stores. It appears these are only available online now and are somewhat expensive. http://www.radioshack.com/product/index ... Id=2262047

I have GE cordless phones (I think they are junk) but they have the output jack on them to go hands free. While I strongly suggest you avoid the GE cordless phones I use them as an example of having the output jack on them. You clip them to your belt and use a headset to go hands free.

These types of phones are meant to use a single or dual ear headset and microphone like those used for gaming "teamspeak" situations. The headset you pointed out should be easily adapted for this type of use. The mic would work outright.

The amplification to the headset should be easy to add as well. There are hundreds of circuits out there for boosting MP3 players and the like. Most are meant for stereo inputs but you could simply build one circuit and output it to both ear pieces. Something as simple as an LM386 amp chip should provide some boost.

Have you tried one of these devices:
http://www.radioshack.com/product/index ... Id=2467974

[rotatepod]

Your replies are great, as usual!

After I returned amplified phone number three I was sure
I had done all that I could do. I couldn't believe how bad
these expensive phones were. The manufacturers always
provided elaborate PDFs describing all the complex stuff
loaded into their phones. With each phone I purchased my
dad would tell me that they didn't work. I never believed him
until I tried them for myself. That $400.00 model looked
more like a NASA space console than a telephone!

I see your point, jollyrgr. The only way to go is buy a phone
that is designed to be used with a headset. That sidetone
you and Bigglez mentioned reminded me of all the hours I
spent years ago studying audio circuits. I'm very glad both
of you jolted my brain into reality.

Before my dad started losing his hearing I think I was like most
people who thought about hearing loss as a relatively easy problem
to cure. You amplify a sound, and the problem goes away! Nothing
could be further from the truth. Hearing loss is as individualistic as
a fingerprint. Some folks do great with hearing aids and amplified
phones, while others can never resolve their hearing problems. My
dad is a bright, highly educated guy. We both know that this is not
going to have a happy ending. The problem is neither one of us is
ready to give up.