I would like to build a hearing aid, appreciate any professional advice

[ronv]

Now I'm thinking something like this for the amplifiers and we could run the whole thing off one lipo cell.
https://www.mouser.com/ds/2/405/tlv2772a-449371.pdf

 

[audioguru]

We do not know how much hearing loss there is. A loss of 12dB needs the output power to be 16 times the power that normal hearing uses.

A person with normal hearing uses headphone with the loudest peaks at 100mW per ear. Then normal peak levels would be -6dB which is 25mW. To allow normal levels when there is a 12dB hearing loss then the earphone will need a peak power of 400mW which is not possible with these little headphones amplifiers for MP3 payers.

 

[ronv]

Are you sure?
I'm no expert but when I did the numbers for the Panasonic 62 mw gave a SPL of 109 db. I would be very hesitant do anything more.

 

[audioguru]

Many "audiophools" with normal (?) hearing blast their headphones with peaks of 115dB. I hear them coming when they are still fairly far away. Then your Panasonic 62 needs 248mW.
I measured peaks of 120dB in a disco many years ago but it did not seem to be too loud.
But we do not know how much hearing loss there is for a deaf person and we do not know how loud they like the sounds to be. Also we are unsure about blasting away the remains of the hearing of a deaf person because we are not ear doctors.

 

[ronv]

I have been using this calculator.
It is nowhere close to your number.

http://www.apexhifi.com/specs.html

 

[audioguru]

Earbuds with a sensitivity of 97dB per mW need 64mW for 115dB per ear.
The TPA6111 stereo amp IC you linked to has an output of 60mW into 16 ohms when its supply is 3.3V. A Li-Po battery cell is 3.2V when it should be disconnected.

Maybe a deaf person needs peak sounds to be louder.
Average conversation level is about 65dB with peaks reaching 80dB.
Wikipedia rates "mild" hearing loss at between 26 and 40dB, "moderate" hearing loss is 41 to 54dB and "moderately severe" hearing loss is 55 to 70dB. There is also severe, profound and total hearing losses listed.

Then a person with a moderate hearing loss of 48dB needs 128dB for normal conversation. Then the power amplifier needs an RMS power rating into 16 ohms of 260mW.

 

[ronv]

OK. I see where you are coming from.
I wouldn't feel comfortable telling 99 to try such high levels. I thought 109 db was pushing it.
But then again I no longer have 20 20 vision with glasses, but I still see a lot better with them than without them.
99, If your still around try this test and lets see how you come out.
https://www.audiocheck.net/testtones_hearingtestaudiogram.php
When will you use this?

 

[audioguru]

Ron, thanks for the hearing test but my pc speakers and/or ears work poorly.

I went blind with cataracts about 5 years ago. Before the cataracts I wore tri-focal glasses for very close, medium and far. I had cataracts surgery where my cloudy natural lenses were removed and replaced with high-tech ones with fixed focus. Now I wear glasses only for very closeup. For medium and far distances my vision is better than 20-20.
Today they have artificial lenses for inside your eyes that can focus near and far like young natural eyes.

 

[dougy83]

There are hearing aids available on ebay from under $10, with tone and volume adjustment (I only saw a single dial, so maybe this is untrue).

If desperate, there's a slim chance that they're usable.

 

[audioguru]

My son bought an "amplified ear" cheap amplifier with mic and earphones from ebay. It did not amplify, instead its output was at the same level as its input with the volume control set to maximum. It had lots of hiss and distortion.

 

[4pyros]

There are hearing aids available on ebay from under $10, with tone and volume adjustment (I only saw a single dial, so maybe this is untrue).

If desperate, there's a slim chance that they're usable.

I think you need to spend a lot more then $10 to get anything good.

 

[Willen]

Hi
Here is a professional hearing add schematic. It just uses 6 pieces of BC547B transistors and need just +1.5 single cell. It has no problem in device, so don't worry!

https://www.electro-tech-online.com/threads/square-wave-audio-out-from-the-hearing-device.140500/

It's professional but it has no equilizer or tone controller. In medical shop, they sell the device at $40 but I could make it less than a dollar. I can buy 40 pieces of BC547B at $1 here.