Author Topic: A hearing Aid Amplifier  (Read 6276 times)

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Offline Md Mubdiul Hasan

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A hearing Aid Amplifier
« on: December 20, 2016, 05:20:31 PM »
Hello Everyone,

Let me introduce one of my project what I worked through 6 years back with a professor.
Still it need to be more efficient.

Its a low cost hearing aid amplifier using LM324 as a main Op-amp.

We were trying to apply 3 frequency selecting gain circuits, 1. Bass Control 2. Mid frequency 3. Treble control.
I did apply some model from online for having suitable gain at human  sensor range like 2-3KHz.

 Take a look in this attachment, sorry for its hand drawing circuit.

I need you valuable suggestions. :-+
 
Hasan
 

Offline Hero999

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Re: A hearing Aid Amplifier
« Reply #1 on: December 20, 2016, 08:08:57 PM »
The first and possibly the most easiest thing you could do to improve it is to use a better op-amp. One which doesn't have the horrible crossover distortion the LM324 does. There are plenty of better op-amps in a similar price bracket which have a class AB output stage and minimal crossover distortion.

TL064
http://www.ti.com/lit/ds/symlink/tl064.pdf

TL074
http://www.ti.com/lit/ds/symlink/tl074.pdf

TL084
http://www.ti.com/lit/ds/symlink/tl084.pdf

MC34074
https://www.onsemi.com/pub/Collateral/MC34071-D.PDF

MC33078/ MC33079
http://docs-europe.electrocomponents.com/webdocs/11a6/0900766b811a6561.pdf

MC3403, MC3303
http://docs-europe.electrocomponents.com/webdocs/12e1/0900766b812e1cf7.pdf
« Last Edit: December 20, 2016, 08:31:22 PM by Hero999 »
 
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Online Rerouter

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Re: A hearing Aid Amplifier
« Reply #2 on: December 20, 2016, 09:16:26 PM »
I went ahead and remade it in a little simulation tool so you can have a play around,

Defiantly agree the LM324 is a rubbish op amp in general,

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?

http://tinyurl.com/gt3p3vs

And the full link below for people trawling through in years to come.

Code: [Select]
http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+9.001713130052181+50+5+43%0Ar+160+288+160+192+0+10000%0AR+160+192+160+144+0+0+40+9+0+0+0.5%0Ac+160+288+256+288+0+1.0000000000000001e-7+0.795344360852607%0Ar+256+288+256+368+0+33000%0Ag+256+368+256+384+0%0Aa+320+304+416+304+1+9+-9+1000000+0.6901185446271082+0.6901254458125545%0Aw+256+288+320+288+0%0Aw+320+320+320+352+0%0Aw+320+352+416+352+0%0Aw+416+352+416+304+0%0Aa+592+384+688+384+0+9+-9+1000000+0.000007269126774086928+0%0Ag+592+400+592+416+0%0Aw+544+368+592+368+0%0Ar+912+384+976+384+0+10000%0Ar+1008+384+1072+384+0+10000%0Ar+992+320+992+384+0+100000%0Ac+544+368+544+304+0+1e-8+0.37088856890630256%0Ac+480+304+480+368+0+1e-8+0.3340798978713451%0Ar+544+304+624+304+0+6800%0Aw+688+384+688+304+0%0A174+480+304+544+336+0+1000000+0.8069000000000001+Bass+Amplitude%0Aw+512+336+512+368+0%0Aw+512+368+544+368+0%0Aw+480+368+512+368+0%0Ar+480+304+416+304+0+6800%0Aw+624+304+688+304+0%0Ac+864+208+928+208+0+1e-8+0.19857312609201755%0Ar+928+240+864+240+0+15000%0Ag+864+240+864+256+0%0Aa+992+304+1088+304+1+9+-9+1000000+-0.19853866235959614+-0.19857312609201755%0Ag+896+336+896+352+0%0A174+864+320+928+336+0+47000+0.797+Volume?%0Aw+976+384+992+384+0%0Aw+992+384+1008+384+0%0Aw+1072+384+1088+384+0%0Aw+1088+384+1088+304+0%0Ar+992+288+928+288+0+100000%0Ar+864+288+800+288+0+15000%0Ac+864+288+928+288+0+1e-8+-0.025256513211524223%0Aw+912+384+768+384+0%0A174+768+320+800+256+0+47000+0.0743+Upper+Attenuation%0Aw+864+208+864+240+0%0Aw+928+208+928+240+0%0Aw+928+240+928+288+0%0Aw+768+320+768+384+0%0Aw+768+384+688+384+0%0Ar+160+288+96+288+0+1000%0Ar+992+320+928+320+0+1500%0A170+96+288+48+288+2+20+4000+1+0.1%0Ar+1120+304+1184+304+0+10000%0Ar+1248+304+1312+304+0+10000%0A174+1184+304+1248+336+0+470000+0.30200000000000005+Upper+Amplitude%0Ac+1216+336+1216+368+0+1e-9+0.0023661890669046215%0Ar+1184+368+1120+368+0+100000%0Ar+1312+368+1248+368+0+100000%0Aw+1312+368+1312+304+0%0Aw+1248+368+1216+368+0%0Aw+1216+368+1184+368+0%0Aw+1120+368+1120+304+0%0Aa+1216+416+1312+416+0+9+-9+1000000+-0.00004411731887452016+0%0Aw+1216+400+1216+368+0%0Aw+1312+416+1312+368+0%0Ag+1216+432+1216+448+0%0Aw+1120+304+1088+304+0%0Ao+61+64+0+2083+10+0.000390625+0+-1+0%0A
 
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Online Kleinstein

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Re: A hearing Aid Amplifier
« Reply #3 on: December 20, 2016, 10:44:50 PM »
There are better OPs around - even the list below is more like the old ones you found 20 years ago. Likely one would use a lower voltage (e.g. 3xAA = 3.6-4.8 V). The resistors are all quite low - for low power something like 10 times the value should be OK.
 
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Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #4 on: December 21, 2016, 12:56:02 PM »
Dear Sir Hero999,

Your first 3 op-amps are available in my sock.
Lets study those datasheet carefully and figure out what feasibility I could get.

Kindly suggest me to improve the design.
« Last Edit: December 21, 2016, 01:26:03 PM by Md Mubdiul Hasan »
Hasan
 

Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #5 on: December 21, 2016, 01:15:19 PM »
Dear Sir Rerouter,

You have made the things easy! :)
Thank you very much.

Having with this nice simulation, lets talk about more what I did in past.
At the same time I will concentrate your simulation.

Quote
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?
Could you explain please more?

I have been separated all  3 circuit parts and feeding with a signal generator.

Take a look my previous graph in this post attachment.
Bass and treble control was  working may be.
Changing POTs position and capacitor values, I saw system.

Can you make comment about +9v and -9v.
I was thinking, to take it in pocket.







« Last Edit: December 21, 2016, 01:31:34 PM by Md Mubdiul Hasan »
Hasan
 

Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #6 on: December 21, 2016, 01:21:17 PM »

Dear Sir Kleinstein,

Quote
Likely one would use a lower voltage (e.g. 3xAA = 3.6-4.8 V).

Could you suggest any in this range ?
Moreover, any MCU which can work all together?
Suggest me any design/manual/reference.

Regards
Hasan
Hasan
 

Offline Audioguru

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Re: A hearing Aid Amplifier
« Reply #7 on: December 21, 2016, 03:59:24 PM »
I am 71 years old and have normal hearing loss of high frequencies for my age (about -40dB at 8kHz). 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. Most settings have AGC but another setting is wideband with not much AGC for music. They produce no electronic noise and never any overload distortion. I am very glad to have them.

Here are graphs of normal hearing loss for men and women at different ages:
 
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Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #8 on: December 21, 2016, 05:19:45 PM »
Dear Sir Audioguru,

Thank you to receive my post.
I am so lucky to have your comment here! :clap:
I raised my hand to make one circuit for my country where people cant buy expensive one!

 
Quote
I could not make hearing aids as small and with as many features as my new hearing aids that are made in Switzerland.
What difficulties you faced during research?

Quote
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
What kind of transducers you have used?

Quote
The hearing aids communicate settings, features and programming between them with Bluetooth.
Did you make MCU firmware ? Which MCU you have been use?


Quote
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.

You might  talking about an advanced one. Position sensor can be used in this case. Was it speech controlled ? with proper DSP?

Quote
They produce no electronic noise and never any overload distortion.

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.


Thank you,.

Regards
Hasan
 

Offline salbayeng

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Re: A hearing Aid Amplifier
« Reply #9 on: December 21, 2016, 05:34:54 PM »
You can combine all the tone controls in one stage,  using baxandall type circuits
eg from here http://www.electro-tech-online.com/threads/baxandall-analysis.129124/


I'm not sure you need a midrange control?  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.
http://www.learnabout-electronics.org/Amplifiers/amplifiers42.php
 
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Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #10 on: December 21, 2016, 07:50:28 PM »
Dear Sir salbayeng,

So kind of you!  :-+

Its a good circuit indeed.
Let me show you what previous circuit I have used. :popcorn:


Lets compare them.

Thank you.

« Last Edit: December 21, 2016, 07:56:08 PM by Md Mubdiul Hasan »
Hasan
 

Offline salbayeng

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Re: A hearing Aid Amplifier
« Reply #11 on: December 21, 2016, 08:05:58 PM »
Looks to be nearly identical, your schematic is designed for single supply operation, as it has a rail splitter (R11,R12).

 

Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #12 on: December 22, 2016, 12:32:49 PM »
Dear Sir salbayeng,

Quote
your schematic is designed for single supply operation, as it has a rail splitter (R11,R12).

Dont you think, depending on Op-amp, power supply should choose ?
Whats the benefit of -Ve and +Ve ? Does not it amplifying signal on both side?
What are the drawback of single supply ?

My main circuit at first post, if you can see my supervisor suggest me to keep the cascaded 3 equalizer in in series !
That means signal from microphone with certain frequency could trapped in one frequency selected portion.
In this time we observed both boost and buck operation gain.
Dont you think its a wrong idea as background noise could directly  appear  to the post amplifier for hearing ? or gains are multiplied ?

If you take a look on your circuit, one portion of equalizer directly connected  to the output, having in parallel action.
In the Bass control section, R8 is connected other Mid and Trable  are connected with capacitors.
Make sense ! Frequency is inversely proportional to capacitor impedance.
During operation, one impedance is active while inactivate others.
Those make huge change on gain.

Let me think it more, because I need a noiseless and distortion free like others.


 
Quote
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.

Well, did you see senior member Audioguru says what in this text? look at his graph.

Keep in touch.
I need your help.







 
Hasan
 

Offline WonderWheeler

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Re: A hearing Aid Amplifier
« Reply #13 on: December 24, 2016, 03:09:56 PM »
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.

Something like this perhaps http://www.banggood.com/E-8-Rechargeable-Hearing-Aid-Sound-Amplifier-for-Two-Ears-Use-FM-Radio-p-1024136.html?rmmds=mywishlist 

or this http://www.banggood.com/V-99-Hearing-Aid-Sound-Amplifier-Portable-Divice-Black-p-1018275.html?rmmds=search 

or this https://www.amazon.com/Pocketalker-Ultra-with-Rear-Wear-Headphones/dp/B00I5PX5C2/ref=sr_1_3?s=aht&ie=UTF8&qid=1482553666&sr=1-3&keywords=pockettalker+ultra

for a bit of a laugh, check this one out http://www.banggood.com/Electric-Tinnitus-Treatment-Instrument-Ear-Hearing-Repair-Device-p-949288.html?rmmds=search

sorry for the long post, just trying to compare ideas
« Last Edit: December 24, 2016, 03:33:53 PM by WonderWheeler »
 
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Offline WonderWheeler

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Re: A hearing Aid Amplifier
« Reply #14 on: December 24, 2016, 03:37:27 PM »
I was even looking at raspberry pi and bat detectors for ideas on how to make a personal hearing aid.
 
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Offline salbayeng

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Re: A hearing Aid Amplifier
« Reply #15 on: December 24, 2016, 03:45:44 PM »
Hi WonderWheeler , welcome to the forum ;D!
Quote
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
Is that a blessing or a curse?  Perhaps a  reward  for putting up with the screeching for all those decades!
I'm barely 4 years behind you! but my hearing is still good, (apart from some selective deafness touch wood!.

BTW if you want to do a partial quote as I did above press the button left of the ebay button and then
[quo te]  cut_n_paste_text_here [/quo te]
(you need to remove the space in "quo te")
or just highlight some text and press the button.
 
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Offline salbayeng

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Re: A hearing Aid Amplifier
« Reply #16 on: December 24, 2016, 03:53:38 PM »
re
Quote
how to make a personal hearing aid
There are quite a few simple schematics on the webs using "jelly bean" transistors google hearing aid schematics .
Have you thought of getting an old style transistor radio , cutting the track going to the volume control and dropping in a electret microphone?
 
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Offline salbayeng

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Re: A hearing Aid Amplifier
« Reply #17 on: December 24, 2016, 04:39:17 PM »
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)
 
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Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #18 on: December 26, 2016, 01:18:07 PM »
Dear Sir WonderWheeler,

My all respects goes to you. :)
Thank you a lot to participate in this post :-+.

Its seems like I need to consider suitable cases while make a  Hearing Aid.


Quote
Am 63 years old myself and am somewhat hard of hearing, probably the result of noise in the workplace etc.
You mean you cant recognize the different tone of sound?

Quote
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.
That means your hearing aid  need to be  consistent at higher frequency gain.


Quote
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.

Can you realize why the manufacturer suggest you to unplug the earphone before you wear it?  Cheapest one can suppress noise from circuits and environment/background?


Quote
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.

I see, did you open the plastic cover and saw how is the circuit ? Kindly give me some idea or reference.


Quote
One cheap one has a built in fm radio. Although you couldn't use both features at once.
This one is multipurpose, lets think about only hearing aid.

Quote
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.
Does the  conductive clip has any communication with a device ?

Quote
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.

Well said, it can be an experiment, but it might need transmitter or receiver  to collect signals from medium.

Quote
I was even looking at raspberry pi and bat detectors for ideas on how to make a personal hearing aid.
OKay, let me know which version of raspberry pi and detectors you have use? If we want to make a cheaper Hearing aid, will it be cost effective using  raspberry pi?

Hope you will response .

Regards
Hasan
 

Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #19 on: December 26, 2016, 01:43:08 PM »
Dear Sir salbayeng,



Quote
I'm barely 4 years behind you! but my hearing is still good, (apart from some selective deafness touch wood!
You looks a professional engineer for sure! :clap:
Let me understand your simulation circuit and graph.

Seems like you are playing with a bjt PNP in CC mode, trying to boosting up the gain of input AC signals putting in base.
Which simulation software you use ?SIMetrix?

I would say, its a good practice to look at the gain over a frequency BW.


Hasan
 

Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #20 on: December 26, 2016, 01:46:07 PM »

Quote
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)

Ok fine. Let me try in this way.
I am usng LTspice and multisim.
Hasan
 

Offline Audioguru

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Re: A hearing Aid Amplifier
« Reply #21 on: December 26, 2016, 02:22:08 PM »
What difficulties you faced during research?
Designing a very complicated circuit, making it very small, finding very small transducers and using a tiny battery.

Quote
What kind of transducers you have used?
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". 

Quote
Did you make MCU firmware ? Which MCU you have been use?
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.

Quote
You might talking about an advanced one. Position sensor can be used in this case. Was it speech controlled ? with proper DSP?
Yes the hearing aids are advanced and are digital, not analog.

Quote
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.
Your circuit is a simple "eavesdropper amplifier" using noisy distorted old opamps and a simple tone controls circuit. 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.
« Last Edit: December 26, 2016, 02:34:20 PM by Audioguru »
 
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Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #22 on: December 26, 2016, 04:41:35 PM »

Quote
Designing a very complicated circuit, making it very small, finding very small transducers and using a tiny battery.
Could you kindly suggest me a design that I can workout for better result. I know advanced design patents are always hidden and should have business policy. Just to make my work as "getting started"


Quote
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".


For such tinny design component, what kind of amplifier you have use? Are you talking about built in amplifier with low noise, distortion free ICs? Its very small size battery, isnt it? Are not you talking about mini or micro scale ! Did you work with energy harvesting circuits?


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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.
I was talking about micro-controller code, you might be talking about end-user software like Android.   

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Maybe you built it on a solderless breadboard and all the wires and rows of contacts are antennas that pickup hum and other interference.
Yes, it could be.

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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.
I am also thinking that things must be programmed where you could have perfect gain level in different frequencies.

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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).
Very significant information, I also believe that in practical result,  LM324, OPA 07/06 will not give a proper answer.

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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.


Was that mission successful ? Dont you mean it needs a huge investment, time , research and manpower?

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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.

If its in Canada, for-sure government will support a lot. Come up with a newer idea in a non-productive environment is time consuming to overcome!
Hasan
 

Offline Audioguru

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Re: A hearing Aid Amplifier
« Reply #23 on: December 27, 2016, 02:47:55 AM »
Instead of making a hearing aid circuit and letting the deaf person fiddle with its controls, the deaf person should have a proper hearing test by an audiologist (my tests were free) to accurately determine the loss frequencies and how much loss. 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.   
 
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Offline Md Mubdiul Hasan

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Re: A hearing Aid Amplifier
« Reply #24 on: December 29, 2016, 06:58:08 PM »

 
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Then the hearing aid should be carefully adjusted by an audiologist to eliminate the losses.
What instrument did audiologist  used to clarify your hearing loss? I mean to understand your hearing loss.


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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.
Yes, looks an abnormal range, my professor was considering 2-3kHz.

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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.
Which feedback you are talking about?

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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. ::)
:=\ wasn't  it a confusion? Perhaps strong sensitivity of your device ! or your unconscious  mind ?


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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 see, real deaf person could feel it. Let me check how much I have lost !

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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. ;)

I am also like your grandson, but I have figure-out that your writing has sharpness, no matter your ears!

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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.
I saw the companies website you recommended, seems like they have technically sound research engineer and resources. People here in South Korea also trying to  make things more tinny with energy harvesting idea. All things we are talking about can be combined in a single chip. I have been working on ECG device under a PhD lab, I saw they use only a IC to cover everything!
]
Hasan
 


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