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I labeled the potentiometers on the right hand columb as i understood there function to be based on the output waveform, to me it seems that 2 of them don't significantly alter it in a way i can grasp?
Likely one would use a lower voltage (e.g. 3xAA = 3.6-4.8 V).
I could not make hearing aids as small and with as many features as my new hearing aids that are made in Switzerland.
My hearing is fine below about 250Hz so vents in the earmolds allow low frequencies to pass then the transducers in each earmold produce the boosted high frequencies
The hearing aids communicate settings, features and programming between them with Bluetooth.
If I hold a phone to one ear the hearing aid in that ear detects it and feeds the sounds to both ears. The microphones are front, back, left and right. Most settings have the directionality aiming at speech in one direction. One setting has higher than normal gain. Another setting has automatic fading of background noise.
They produce no electronic noise and never any overload distortion.
your schematic is designed for single supply operation, as it has a rail splitter (R11,R12).
Hearing aids have a fairly limited frequency range (not as much as 100Hz to 10kHz) so you could squash together the bass and treble cutoffs.
The thing I am missing most is the treble or high part of the spectrum. I understand that is common with men. For that reason, women with higher frequency voices are harder to understand
how to make a personal hearing aid
Am 63 years old myself and am somewhat hard of hearing, probably the result of noise in the workplace etc.
The thing I am missing most is the treble or high part of the spectrum. I understand that is common with men. For that reason, women with higher frequency voices are harder to understand. I need to boost the high part to make out consenents, the different sounds of "c" or "s" or "t" is hard to differentiate, and all sound the same to me.
I have been looking at Amazon and such for some cheap pocket sized units and noticed some things to look out for. The cheapest ones don't have a switch to boost , high frequency or to cut out low frequency (noise).Some have directions that say to unplug the earphone before you turn it on or you blow your ears out, lol. Watch out for that.
Another one used a mono earphone socket to save a few cents, even though stereo sockets are available. It meant that if you plugged in a typical stereo headphone you would hear out of only one earpiece, lol. The recommended purchase of an adapter for 5 usd to change the mono signal to stereo.
One cheap one has a built in fm radio. Although you couldn't use both features at once.
One cheap one was a hearing aid in one position then in the other setting had in some kind of weird Chinese concept would send a signal to your earlobe with a conductive clip acting as an electrode as a quack cure for tinnitus. Through some kind of acupuncture idea.
For me the ideal unit would work with an fm radio, could get distant stations maybe some kind of short antenna, would have an oversized battery like maybe AA, would automatically turn itself off if not being used, boost high frequency sound, and be used kind of like an mp3 player.
I was even looking at raspberry pi and bat detectors for ideas on how to make a personal hearing aid.
I'm barely 4 years behind you! but my hearing is still good, (apart from some selective deafness touch wood!
Something like this......
This uses the electret standoff voltage to bias the transistor, this might need tweeking (by changing VR2 and R3 together , note that R3 should be 1/10 of VR2 , and C1 goes up as R3+Vr2 go down)
The base of Q1 should be ~ 2/3 of VCC (if transitor saturates then tap the base in halfway along R4)
What difficulties you faced during research?
What kind of transducers you have used?
Did you make MCU firmware ? Which MCU you have been use?
You might talking about an advanced one. Position sensor can be used in this case. Was it speech controlled ? with proper DSP?
I saw many unwanted signal accumulated from background with this simple circuit, something like antenna is collecting things. Kindly, put your valuable suggestion about develop this circuit.
Designing a very complicated circuit, making it very small, finding very small transducers and using a tiny battery.
My transducers are about 2mm diameter and 5mm long and are inserted into the earmolds that are in my ear canals. The actual hearing aids are placed over the ears and are about 18mm long, 5mm high and 3mm thick. The batteries are one tiny button cell #312 (1.45V zinc-air) in each hearing aid and are replaced every 8 days (they are turned off each night). The hearing aids beep or say "low baddery".
I tried a demo of Widex brand hearing aids but I did not like their sound, I tried then bought Phonak brand hearing aids. The hearing tests were free and the demos were free for 30 days each.
Maybe you built it on a solderless breadboard and all the wires and rows of contacts are antennas that pickup hum and other interference.
My hearing aids are programmed to produce wideband and wide level sounds when in the "music" mode. They sound so natural that I forget I have them on.
Cheap old circuits do not produce enough high frequency boost (mine have +40dB which is 100 times more signal level but a simple tone controls is only +10dB (only 3.2 times more signal level).
Hearing aids are expensive and the audiologists who program them are highly paid skilled professionals. Before I retired I made enough money working to buy everything I wanted and more for investments.
The interest on my investments pays for my expenses now. Also my government is paying me a pension. My government paid for a portion of the cost of my hearing aids. My government also paid for a portion of the cost of deluxe lenses in my eyes when I had cataracts surgery and completely paid for my heart attack surgery so now I am young again.
Then the hearing aid should be carefully adjusted by an audiologist to eliminate the losses.
My hearing aids came adjusted for severe high frequency loss with a feature where the highest octave from 10kHz to 20kHz was shifted down to 5kHz to 10kHz but I did not like how that sounded so it was eliminated and the highest frequencies were boosted as much as is possible. Now the sound is natural.
I did not like the anti-feedback program that caused continuous high frequency tones or beeps to flutter so in the Music Mode it was turned off and sometimes there is high frequency feedback.
I asked for one Mode to have very high sensitivity which is useful and playful. Then at a conference I can clearly hear what a far away person is mumbling but most people cannot hear him. I was walking in the mall with the hearing aids set to the Very Sensitive Mode and I heard a woman behind me call my name. I turned around and nobody was there but there was a woman far away on the phone talking to somebody that has my name.
The directionality of the four microphones (left, right, front and back) reduces background noises but sometimes they switch oddly. I was talking with my wife in front of me and when she paused the microphones switched to somebody talking behind me. When my wife began talking again then the hearing aids had to think about switching back to her or not which caused a delay.
I am a new grandfather. When my grandson cries I switch the hearing aids to the Muted Mode to reduce his loud cries and the same when my dog barks when there is somebody at the door. When the hearing aids are muted then I cannot hear my wife scold me.
Since the transducers are tiny then their sound hole becomes plugged with normal ear wax. The hearing aids have a replaceable filter covering the hole which I change when I replace the battery cell.