A hearing Aid Amplifier  - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 20, 2016, 06:20:31 am
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: December 20, 2016, 09:08:57 am
content: 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.TL064http://www.ti.com/lit/ds/symlink/tl064.pdfTL074http://www.ti.com/lit/ds/symlink/tl074.pdfTL084http://www.ti.com/lit/ds/symlink/tl084.pdfMC34074https://www.onsemi.com/pub/Collateral/MC34071-D.PDFMC33078/ MC33079http://docs-europe.electrocomponents.com/webdocs/11a6/0900766b811a6561.pdfMC3403, MC3303http://docs-europe.electrocomponents.com/webdocs/12e1/0900766b812e1cf7.pdf

author: Rerouter
author_rank: Super Contributor
timestamp: December 20, 2016, 10:16:26 am
content: 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/gt3p3vsAnd the full link below for people trawling through in years to come.Code: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

author: Kleinstein
author_rank: Super Contributor
timestamp: December 20, 2016, 11:44:50 am
content: 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.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 21, 2016, 01:56:02 am
content: 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.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 21, 2016, 02:15:19 am
content: 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.QuoteCould 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.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 21, 2016, 02:21:17 am
content: Dear Sir Kleinstein,QuoteCould you suggest any in this range ?Moreover, any MCU which can work all together?Suggest me any design/manual/reference.RegardsHasan

author: Audioguru
author_rank: Super Contributor
timestamp: December 21, 2016, 04:59:24 am
content: 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:

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 21, 2016, 06:19:45 am
content: Dear Sir Audioguru,Thank you to receive my post.I am so lucky to have your comment here!I raised my hand to make one circuit for my country where people cant buy expensive one!QuoteWhat difficulties you faced during research?QuoteWhat kind of transducers you have used?QuoteDid you make MCU firmware ? Which MCU you have been use?QuoteYou might talking about an advanced one. Position sensor can be used in this case. Was it speech controlled ? with proper DSP?QuoteI 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

author: salbayeng
author_rank: Frequent Contributor
timestamp: December 21, 2016, 06:34:54 am
content: You can combine all the tone controls in one stage, using baxandall type circuitseg from herehttp://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

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 21, 2016, 08:50:28 am
content: Dear Sir salbayeng,So kind of you!Its a good circuit indeed.Let me show you what previous circuit I have used.Lets compare them.Thank you.

author: salbayeng
author_rank: Frequent Contributor
timestamp: December 21, 2016, 09:05:58 am
content: Looks to be nearly identical, your schematic is designed for single supply operation, as it has a rail splitter (R11,R12).

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 22, 2016, 01:32:49 am
content: Dear Sir salbayeng,QuoteDont 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.QuoteWell, did you see senior member Audioguru says what in this text? look at his graph.Keep in touch.I need your help.

author: WonderWheeler
author_rank: Contributor
timestamp: December 24, 2016, 04:09:56 am
content: 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 perhapshttp://www.banggood.com/E-8-Rechargeable-Hearing-Aid-Sound-Amplifier-for-Two-Ears-Use-FM-Radio-p-1024136.html?rmmds=mywishlistor thishttp://www.banggood.com/V-99-Hearing-Aid-Sound-Amplifier-Portable-Divice-Black-p-1018275.html?rmmds=searchor thishttps://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+ultrafor a bit of a laugh, check this one outhttp://www.banggood.com/Electric-Tinnitus-Treatment-Instrument-Ear-Hearing-Repair-Device-p-949288.html?rmmds=searchsorry for the long post, just trying to compare ideas

author: WonderWheeler
author_rank: Contributor
timestamp: December 24, 2016, 04:37:27 am
content: I was even looking at raspberry pi and bat detectors for ideas on how to make a personal hearing aid.

author: salbayeng
author_rank: Frequent Contributor
timestamp: December 24, 2016, 04:45:44 am
content: Hi WonderWheeler , welcome to the forum!QuoteIs 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.

author: salbayeng
author_rank: Frequent Contributor
timestamp: December 24, 2016, 04:53:38 am
content: reQuoteThere are quite a few simple schematics on the webs using "jelly bean" transistors googlehearing 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?

author: salbayeng
author_rank: Frequent Contributor
timestamp: December 24, 2016, 05:39:17 am
content: 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)

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 26, 2016, 02:18:07 am
content: 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.QuoteYou mean you cant recognize the different tone of sound?QuoteThat means your hearing aid need to be consistent at higher frequency gain.QuoteCan 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?QuoteI see, did you open the plastic cover and saw how is the circuit ? Kindly give me some idea or reference.QuoteThis one is multipurpose, lets think about only hearing aid.QuoteDoes the conductive clip has any communication with a device ?QuoteWell said, it can be an experiment, but it might need transmitter or receiver to collect signals from medium.QuoteOKay, 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

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 26, 2016, 02:43:08 am
content: Dear Sir salbayeng,QuoteYou looks a professional engineer for sure!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.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 26, 2016, 02:46:07 am
content: QuoteOk fine. Let me try in this way.I am usng LTspice and multisim.

author: Audioguru
author_rank: Super Contributor
timestamp: December 26, 2016, 03:22:08 am
content: Quote from: Md Mubdiul Hasan on December 21, 2016, 06:19:45 amDesigning a very complicated circuit, making it very small, finding very small transducers and using a tiny battery.QuoteMy 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".QuoteI 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.QuoteYes the hearing aids are advanced and are digital, not analog.QuoteYour 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.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 26, 2016, 05:41:35 am
content: QuoteCould 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"QuoteFor 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?QuoteI was talking about micro-controller code, you might be talking about end-user software like Android.QuoteYes, it could be.QuoteI am also thinking that things must be programmed where you could have perfect gain level in different frequencies.QuoteVery significant information, I also believe that in practical result, LM324, OPA 07/06 will not give a proper answer.QuoteWas that mission successful ? Dont you mean it needs a huge investment, time , research and manpower?QuoteIf 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!

author: Audioguru
author_rank: Super Contributor
timestamp: December 26, 2016, 03:47:55 pm
content: 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.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 29, 2016, 07:58:08 am
content: QuoteWhat instrument did audiologist used to clarify your hearing loss? I mean to understand your hearing loss.QuoteYes, looks an abnormal range, my professor was considering 2-3kHz.QuoteWhich feedback you are talking about?Quotewasn't it a confusion? Perhaps strong sensitivity of your device ! or your unconscious mind ?QuoteI see, real deaf person could feel it. Let me check how much I have lost !QuoteI am also like your grandson, but I have figure-out that your writing has sharpness, no matter your ears!QuoteI 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!]

author: Audioguru
author_rank: Super Contributor
timestamp: December 29, 2016, 05:00:08 pm
content: Quote from: Md Mubdiul Hasan on December 29, 2016, 07:58:08 am

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 30, 2016, 05:28:44 am
content: QuoteI see, these booth are available in any ENT medical center?QuoteIf so, then what amplifier system you prefer? If we need boosted gain in high frequency, what should be the basic IC ? Can you suggest any company like TI,AD,Linear, ST?or, you suggest raspibary pi?QuoteDont you think, I need a survey at my won country considering in-general deaf people?. Yes, I do believe your graph.But from your experience, it looks critical deaf person need special hearing aid.QuoteLet me know, which way(circuit system) you feel it poor and inadequate capabilities.QuoteThen which point you think, need to be work in this case ? In what device you find this information?QuoteYes I heard so, I am working in this country as an Engineer but my mother land in Bangladesh. I am thinking about my poor people who need a cheaper one, I know china get priority in our market, but no trend has been build up internally who can make circuits,pcb patent along with good research activities.

author: Audioguru
author_rank: Super Contributor
timestamp: December 30, 2016, 08:45:04 pm
content: Quote from: Md Mubdiul Hasan on December 30, 2016, 05:28:44 amThe soundproof booth used for hearing tests is available at every hearing aid clinic. In my small city there are about 15 hearing aid clinics. I had free hearing tests at 3 of them.QuoteMy hearing aids are digital but they must use some analog circuits in their custom made IC. I do not know any opamp that can be powered from only 1.45V at an extremely low current like my hearing aids.QuoteSince all old people lose high frequency hearing sensitivity then they all need hearing aids programmed to eliminate their loss after a proper hearing test but many old people do not care about hearing sounds properly or cannot afford the high cost of a hearing aid.QuoteI worked with high quality telephone and video conferencing systems. They use a digital echo canceller to make a model of the acoustics (frequencies and their phases) and use it to cancel feedback sounds.Hearing aids should also do it like that.QuoteHearing aids with front, back, left and right mics can use a comparator to determine the loudest sounds at voice vowel frequencies and their direction.

author: WonderWheeler
author_rank: Contributor
timestamp: December 31, 2016, 06:24:52 am
content: Quote from: Audioguru on December 29, 2016, 05:00:08 pm

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 03, 2017, 08:08:08 am
content: Dear Sir Audioguru,Hope you celebrate a very special "Happy New Year".Lets pray for you to have a nice staring of 2017.Sorry for my late reply, I was busy on PCB design.QuoteDont you mean its a build-in IC? I saw a small size SpO2 (pulse-oxymeter) from German company, its main mcu was really hidden and I found no further information other then simple SPI data reading format.QuoteQuoteDidnt you get any idea of "echo canceller" on circuits ? It might be in case of software resolution on signal. I dont know how unwanted signals could cancel through DSP, its obviously far away from any hardware filter. Patterns of speech, tone etc component could be meaningful if you play with them in algorithm. Most interesting thing is how the data looks like? How you captured them on program.QuoteWell said, even the initial design could be bulky but we can see how the loudest sound gain on particular frequencies changes on direction.RegardsHasan

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 03, 2017, 08:21:14 am
content: Dear Sir WonderWheeler,Happy new year 2017.Thank you as you noticed our conversation.QuoteLG is not interested on small size medical device I heard.QuoteCould you kindly talk more about it, "telemedicine " facilities is being popular in the region I have born.Best RegardsHasan

author: BrianHG
author_rank: Super Contributor
timestamp: January 03, 2017, 12:00:43 pm
content: I am curious if anyone has though of using a beamforming microphone, there is one on my laptop for video conferencing in noisy environments like a coffee shop. Combine such a mic with active acoustic cancellation headphones (ear bud sized) with audio input on each ear for the hearing impaired. The headphones gets rid of all outside sounds completely while a forward aimed beamforming mic would really focus ones hearing on whoever they are looking at in front of them even in a noisy environment. Obviously for the mic, you should also be able to EQ it, but you wouldn't have to worry as much about feedback. I do realize this is a costly combination of tech.

author: Audioguru
author_rank: Super Contributor
timestamp: January 03, 2017, 04:33:26 pm
content: The conference system that I worked with used a digital echo-canceller IC that required setup by playing pink noise through the speakers into the room and the mic picked it up and compared it with the original signal and made a model of the acoustics (frequencies and their phases) of the room. Then when sounds from the speakers are picked up by the microphones the echo canceller circuit cancelled them from producing acoustical feedback. It even worked with long distance that has a delay: I talk and my voice goes to the distant end where its mic picks up the speaker sound and the echo canceller at the distant end prevented my voice from coming back to me as an echo.Quote from: BrianHG on January 03, 2017, 12:00:43 pmSince my hearing aids use 4 microphones and since the one that has the strongest sound pickup is given the most gain, then the mics must be directional. Noise cancellation is also done in my hearing aids except not in the Music Mode.Frequently when I am in a store or in a mall I hear a song that I like playing very faintly on the background music system. I push the button on my hearing aid so that they go into the very sensitive mode then I hear the music playing loud and clear. The background noise does not increase so it must be cancelled a little and I think the very high frequencies are reduced a little.

author: m98
author_rank: Frequent Contributor
timestamp: January 03, 2017, 04:48:23 pm
content: Quote from: Audioguru on December 30, 2016, 08:45:04 pmThere you go:http://www.ti.com/lit/ds/symlink/tlc25l4b.pdfhttp://www.ti.com/lit/ds/symlink/lmv951.pdfhttps://datasheets.maximintegrated.com/en/ds/MAX4036-MAX4039.pdf

author: BrianHG
author_rank: Super Contributor
timestamp: January 03, 2017, 05:11:16 pm
content: Quote from: m98 on January 03, 2017, 04:48:23 pmWOW!

author: Audioguru
author_rank: Super Contributor
timestamp: January 03, 2017, 06:39:07 pm
content: The WOW opamp is fantastic when it has a 1V supply. It could be used in a simple DIY hearing aid.

author: BrianHG
author_rank: Super Contributor
timestamp: January 04, 2017, 04:53:04 am
content: The WOW opamp is rated to work at 0.9v. Maybe a fraction lower.With a little tuning of the circuit below for adjusting 3 frequency bands something like 3khz 6khz & 10khz, you can make a cheap but fairly functional device.Quote from: salbayeng on December 21, 2016, 06:34:54 am

author: Inflex
author_rank: Regular Contributor
timestamp: January 04, 2017, 05:05:06 am
content: Watching with interest. Ever since I sadly washed my hearing-aids at the age of 22 (a loooooong time ago now) I've just gotten on with life without them because of the cost, thank goodness for the internet and everyone being able to communicate using text

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 04, 2017, 06:47:10 am
content: Thank you sir BrianHG,Welcome to my post..QuoteDid you read any article on this? Kindly explain more.QuoteAny particular design will be appreciable.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 04, 2017, 06:52:08 am
content: QuoteYes, Mr. salbayeng also suggest this design in this post.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 04, 2017, 06:54:36 am
content: Sir m98.Thank you for useful datasheet.Need to think for application circuits.

author: Inflex
author_rank: Regular Contributor
timestamp: January 04, 2017, 06:57:08 am
content: Quote from: Md Mubdiul Hasan on January 04, 2017, 06:47:10 amWhen I was a student at high-school, I tried the headphone / directed-microphone system, using a portable FM pocket radio and a "Talking Electronics" FM Bug with a shrouded mic, it was an excellent combination for me, so yes, being able to focus on sounds is a great idea when you're talking to people.A system I want to try build here now is something which picks up sounds from all around the house and mixes them with the audio in the room I'm in; sort of giving me far greater situational-awareness. I like to be able to hear if my cats are calling out to me / in trouble, or likewise my wife.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 04, 2017, 06:58:27 am
content: QuoteI see, in old days which circuits you were interest in?

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 04, 2017, 07:04:09 am
content: QuoteWhat noise level you are thinking ? What senors you are trying to use ?Cant you combined with possible earth quack signals that is important now in a risky area.

author: Audioguru
author_rank: Super Contributor
timestamp: January 04, 2017, 03:37:45 pm
content: The maximum amount of high frequency boost in the simple tone controls circuit is 10dB which is good for a man no older than about 30 years old according to the normal hearing loss graph I posted. Today I am 71 years old with a normal more than 40dB of loss at 10kHz and my audio system's treble tone control does almost nothing without my hearing aids and their more than 40dB of boost.60 years ago hearing aids produced telephone quality (300Hz to 2kHz)*. Music goes to 20kHz and speech goes to at least 14kHz and modern hearing aids play them well.The earmolds for my hearing aids have vents so that air pressure changes are allowed then they do not cause a "plugged feeling" and the vents also allow normal level low frequencies to be heard directly. but the vents cause feedback that must be eliminated.When you make a whole house microphone system then you will have feedback unless you wear sealed headphones. Maybe the microphone system can light a bulb or ring a bell instead (and something to turn them off).* I measured a loss of -12dB at 3kHz on a telephone line at work. I complained to Bell and they said it is fine and is better than their maximum allowed loss of -15dB. The response began dropping at 1kHz. Vowels only.

author: digital_dreamer
author_rank: Newbie
timestamp: January 05, 2017, 03:32:16 am
content: Quote from: Audioguru on December 29, 2016, 05:00:08 pmMy hearing aids are Starkey Destiny 400 BTE (Behind The Ear) and implement a anti-feedback algorithm where the output is frequency shifted (up or down, don't remember which), so that each time it re-enters, it's continually shifted until nulled. It's quite effective, as one of the more embarrassing things that can happen is having your aids hanging off your ear or in your pocket while still turned on and people looking at you like WTH is going on with you?Not anymore with these. These are the first digital ones I stuck with, as I hadn't had good experiences with digital. Really prefer the old analog.I'm 52 and have worn aids all my life, as I was born with profound hearing loss from birth, like my twin brother. My frequency loss starts at 500Hz, yes, really. And, is off the chart at 2KHz (below -110db), so no amount of amplification is going to help there.We always wear BTE, as they are the only types that usually have the power needed with the large enough battery to last.Funny story: Hearing loss got me started in electronics and sound. I started tinkering with amplifiers as a kid and entered a regional Science Fair at age 13 and won first place in Physics with a telephone amplifier I hacked together from a radio and a magnetic pickup coil. I still had a lot to learn, as I used a linear pot for the volume control and demonstrated that there was still plenty of volume when turned all the way down. LOL.I'm a digital guy through and through, however, building digital circuits and programming MCUs and such.Anyhow, I'm enjoying this thread and applaud any efforts in this field. As much as I enjoy technology and having the latest of the greatest, my experience with aids has exposed many problems in this field. The aids offer so many features and options that my main aid seller, as well as several other "professionals" that offered to fine tune these aids and fix my issues, were baffled for hours trying to figure out what to do and what to change on the software connected to the aids. This took many visits and I was left giving up on having some issues ever resolved.One of the issues was the hearing aid confusing music as noise and always tuning it out. This was a problem I had many years prior when I was testing out a digital aid. I worked in a printing plant and needed to hear the equipment running, including pressurized air or vacuum, and drive motors. Having the aids constantly trying to tune out the sounds was extremely annoying, so I returned them. I needed to hear the noise! This was finally fixed, however, by finding a way to turn it OFF. Probably a disappointment to the team of DSP programmers who spend weeks/months making this "work."The other issue was just simply having the telephone pickup work. This was supposed to work automatically or you could switch it manually. But, no. Unlike any hearing aid in the past, I cannot use these on any hearing-aid compatible phone. What's the point offering all these bells and whistles if no one knows how to make it all work? Inexcusable for a $3000/aid system.Now, I like the idea of BT enabled aids and other features, but when it really comes down to it, all we really need is a good, low-power, sensitive mic, amplifier, and transducer, coupled with a 2 or 3-band filter. Everything else is gravy.MAJ

author: Audioguru
author_rank: Super Contributor
timestamp: January 05, 2017, 03:56:21 am
content: I tried frequency shifting to eliminate feedback in a PA system but it added strange sounds.The echo canceller in conference systems also made weird sounds when the acoustics in the room changed due to many people coming or going and it got confused since its model of the acoustics is different.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 06, 2017, 06:17:01 am
content: Hello,Thank you to join hereQuoteLet me know your digital design more.QuoteFor real application, what did you feel for size of battery.?Quote.Dont you think, its more about Physics rather then engineering work!QuoteWhat MCUs you have programmed, did those related with PA,Hearing aid or telephone system?Quote

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 06, 2017, 06:20:24 am
content: QuoteWhen you were talking about "feedback" microphone system, I feel need to work on that on my design.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 06, 2017, 06:23:01 am
content: QuoteFor the case of acoustics and echo canceller, cant we use a simulation software ?Can you remember from your stock ?

author: Audioguru
author_rank: Super Contributor
timestamp: January 06, 2017, 01:30:10 pm
content: Quote from: Md Mubdiul Hasan on January 06, 2017, 06:23:01 amAt first, the echo canceller makes a model of the acoustics of the room when pink noise is played through the speakers and is picked up by the microphones and its frequency response and phases are analyzed and saved. The echo canceller is "adaptive" so it tries to use incoming speech as its signal and makes changes to the model of the room acoustics to make the model accurate if it detects changes to the model.Cirrus Logic and other manufacturers make echo canceller ICs. Polycom speakerphones use an echo canceller so that they are "full duplex" (you can talk and listen at the same time without having feedback or switching).

author: WonderWheeler
author_rank: Contributor
timestamp: January 07, 2017, 12:01:28 am
content: Quote from: Md Mubdiul Hasan on January 03, 2017, 08:21:14 amHasan:"Appropriate Technology" in the US, was a reaction against the 1970s culture that created the "Vietnam War", environmental pollution, and overconsumption and waste of natural resources.https://en.wikipedia.org/wiki/Appropriate_technologySmart, long haired college students, that were shall we say smokers rather than drinkers, thought that maybe a new type of technology could fix culture. Something that involved village scaled technologies, using methane digestors to produce gas, solar water heating, rammed earth walls, solar electricity, vegitarianism, windmills, democracy, cooperative businesses and other low tech solutions.The state of California even had an office called OAT, where some friends and I got a small grant to do a video on solar in the 70s.It later looked like A.T. was just wishful thinking, and right wing polititions took control.... sorta like today, lolRegardless... a small durable cheap open source hearing aid could do a lot for poor people around the world. Partial hearing loss due to age or an infection.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 09, 2017, 03:40:59 am
content: Dear Sir WonderWheeler,Thank you to describe things well.Let me write beside your comments.QuoteBeside "robots" what electronics idea you can imagine for such solution ?QuoteNice, still those solution is MUST in developing countries.QuoteA short lasting cheap circuit has good business in my country, I am looking for a good design at least to start. Need to develop a patent that cant be copied by others.

author: Audioguru
author_rank: Super Contributor
timestamp: January 09, 2017, 05:04:45 pm
content: A patent is given to somebody who invents something that has not been done before. Hearing aid circuits are not new and cannot be patented.You want to design a hearing aid that is CHEAP with poor performance. There are many of them in China, look at Banggood.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: January 10, 2017, 07:45:45 am
content: Thank you sirQuoteYou might talking a very tinny one, lets see inside.