BOSE Hearing Aids and Hearing Assist Technology

[jedishrfu]

The FDA approved a new class of hearing devices, BOSE hearing aids as described in this Tech Crunch article:

https://techcrunch.com/2018/10/05/bose-hearing-aid-gets-fda-approval/
What's unique is that they are self adjusted via a phone app and don't require a audiologist to perform the work.

They aren't out yet but there is another class of devices called hearings assists that are:

- BOSE Hearphones = headphones + hearing assists with directionality, adaptive noise cancelling and other adjustments for environment
- various cheap behind the ear hearing assists.

I bring this up because like many people my age, my hearing is fading over time and I was having trouble conversing when I couldn't hear what was said. Sometimes the voices would be muffled or the person said something unexpected and I couldn't tease out what they had actually said often resulting in confusion on my part.

Other times while driving, the car noise was enough to blank out the conversation leaving me in the dark trying to drive while trying to understand what was said without asking for the speaker to repeat it several times or skipping it and then getting the rejoinder that "I told you didn't you hear!" later on.

Anyway, I found the Bose hearphones and am evaluating them now and they seem to be a viable alternative to actual hearing aids for mild to moderate hearing loss ie $500 vs $2000-$8000 price ranges. They have bluetooth capability and adjusting noise cancelling.

They can be changed for focused person to person or semicircle or full circle directionality. The ear balance can be changed to boost one ear over the other. They can adjust the treble response...

What they can't do and that hearings can do is to individually adjust frequency bands boosting one over the other to bring your hearing back to a reasonable range but never as good as it was originally (so as to not overdrive the ear I think). They also cannot do frequency shifting which a higher frequency range shifted down a bit for those with total high frequency hearing loss.

I hope this isn't considered an advertisement and I'm not being paid to talk about them. I thought some folks here that are on the edge about hearing aids might like to know that there are other options.

Here's an audiologists take on the hearphones which is what got me interested in them:

 

[jedishrfu]

As a secondary comment, my students did a summer project last year where we constructed a similar device although not as polished.

Basically, we used two USB lapel mics with -40db sensitivity connected to a Raspberry-PI along with headphones for listening. The idea was that the PI would perform rudimentary beamforming ie add the left and right signals to emphasize person to person hearing assist.

We thought they could be used by an auditorium speaker trying to hear the question of a student at 60 ft away. Human speech is 70db when 1 foot away from the speaker and drops 6db for each doubling of the distance.

1 ft = 70db
2 ft = 64db
4 ft = 58db
8 ft = 52db
16 ft = 46db
32 ft = 40db
64 ft = 34db

The few takeaways we learned:
1) Don't buy cheap lapel mics (our USB lapel mics both had the same fixed USB address)
2) Don't buy cheap mics period (the sensitivity varied between them and they need to be balanced)
3) The raspberry-pi introduced a noticeable delay of 1/10 sec or so that sounded a bit like an echo
4) The mics should be placed near each ear using the head for separation of the soundspace

Our device looked like a Texas longhorn steer headset with the horn tips for the mics made of structured foam plastic attached to the headphones. Wearing them made you look like a reject from the Mickey Mouse club or a cheerleader at a football game. However, it was a fun project and the students learned a lot.

 

[anorlunda]

I owned a gadget 5-7 years ago that paired a phone with the hearing device. Tap a button and the phone app started running a hearing test, just like the audiologist test. When done it uploaded the results to the hearing device.

I considered a home brew microphone plus headphones rig because my hearing aids aren't loud enough. But after experimenting with TV headphones m i found that it must have a high pass filter. Otherwise it overloads my ears low frequency volume and causes pain. A simple passive filter might do the m job.

Expensive hearing aids claim to do nonlinear speech augmentation and background noise suppression but I am unable to independently verify their claims.

 

[Laroxe]

I remember watching a youtube review of some bluetooth earphones, they are a bit big but the reactions of the people trying them was interesting. I think this technology is developing so quickly it seems inevitable that this sort of thing will replace traditional aids. They are already getting to the size of some of the in ear aids and are getting an increasing number of features.

The digital technology is far better than simple amplifiers because they can be so fine tuned to the hearing loss and they do help particularly with speech. Age related hearing loss effects particular frequencies so selective amplification is far better, currently you could probably get away with in ear units which are virtually invisible but a bit expensive. I think wearing these headphones would get a bit irritating and selective amplification preserves your hearing better, you may only need one aid initially. Its also difficult to know how long any benefit will last from the headphones and cosmetically they seem a step backwards. Starting to use aids for the first time is an experience in itself you become aware of lots of new sounds.

I'm not sure about the FDA approval, that often seems simply a way to double the price because it becomes a medical device.
The video;

 

[jedishrfu]

The tuning issue with digital could be a problem as low power devices run at low frequency meaning there will be a potential processing delay.

I had that experience processing stereo mikes thru a raspberry pi. It was a proof of concept idea but it had a noticable echo effect.

 

[sophiecentaur]

Expensive hearing aids claim to do nonlinear speech augmentation and background noise suppression but I am unable to independently verify their claims.

This is something I'm interested in and I found your post from 2019. I've been using the UK National Health Service hearing aids for at least ten years and I have to be honest, they make a huge difference. Moreover, they are free and I've had upgrades at least twice.

But the test procedure is no more than a 'squeak' to find my threshold over the normal hearing range. They communicate with each other and provide gain control and something like mike pattern choice.

I would pay money for an improvement but the problem would be if I didn't get anything detectable for my £3k+. I understand that the NHS models are 'old' models which have paid the development costs already. I do hate these 'black magic' things for which punters pay through the nose and have only blind faith to judge them by.

Have you followed up on any of this stuff since 2019?

 

[jrmichler]

Back in 1986, I built a hearing aid. My father knew that he needed a hearing aid, but had a neighbor that had spent $1400 for a hearing that was unusable. He was not about to repeat that, but:

He could hear me clearly and easily.
He could barely hear my mother.
He could not hear the attractive young female bartender at his favorite bar.
He could not hear the attractive young female friend of the family, and needed my mother as interpreter to talk to her.
He could not hear Barbara Walters (TV person).

So he got an audiogram. This one:

So we set up an experiment. A microphone connected to an octave band equalizer with the gains set as indicated by the audiogram connected to a stereo amplifier set for maximum treble and minimum bass connected to headphones. This worked. He could hear the refrigerator, he could easily hear my mother doing her Donald Duck voice (don't ask), and no change in hearing me. He was now convinced that a properly designed hearing aid would give him the hearing that he wanted.

So I found a book titled Handbook of Simplified Solid State Circuit Design, in which was a circuit for an audio frequency bandpass amplifier. I ended up with a circuit in a Radio Shack project box that fit into a shirt pocket. That plus a tie pin microphone and ear buds resulted in a hearing that nicely met his needs. He took that to a hearing aid place, and they sold him a pair of hearing aids for $440 that met his needs.

 

[jedishrfu]

So your device boosted the higher frequencies.

There is another approach that is taken for some types of hearing loss where the higher frequencies are remapped to lower ones.

 

[hutchphd]

There is another approach that is taken for some types of hearing loss where the higher frequencies are remapped to lower ones.

Does anyone know a good technical description of this process? ( I think the generic term is "companding" ?)

 

[sophiecentaur]

There is another approach that is taken for some types of hearing loss where the higher frequencies are remapped to lower ones.

This mapping would involve down-conversion (mixing) of the hf parts of the spectrum along the same lines that those gizmos work for listening to bat squeaks (and every standard radio receiver operates). That would certainly help a seriously deaf person to be aware of hf and the brain could well learn to process what it gets to improve hearing sensitivity. Fabulous result for someone with very impaired hearing but the result could lose the 'natural sound' that I, for example, would need to think twice about (as I'm not that bad).

Thing is, my existing NHS hearing aids are really not that bad. My acoustic lives with and without the aids in, are certainly different. I just wonder how much better the result of spending £3k extra would be. Whatever my Oticon aids do may involve more than just hf boost but all the test did was (apparently) to look at my frequency response. Smaller and re-chargeable are not worth spending vast amounts of money on if that would be the only difference.

I resent HiFi type marketing and so do many other PF members!!

Does anyone know a good technical description of this process? ( I think the generic term is "companding" ?)

The original use of the term came from, Compression and Expanding, which is used to fit an audio recording (or transmission) to a noisy channel. Quiet passages were transmitted at a higher level, to improve signal to noise ration and louder passages were transmitted at lower level, to give enough 'headroom' to avoid distortion. That was the compression. The received signal was expanded, to reduce the level of the quieter passages and, of course reduce the level of the noise when it would be audible. Early Dolby more or less did that.

So companding requires post processing of the signal to match the pre processing. I don't know what processing human 'hearing' could do - unless it already does clever stuff with the sound (which it may well do, of course). And Marketing could well have borrowed a term from the legit engineering world etc. etc.

 

[sophiecentaur]

He took that to a hearing aid place, and they sold him a pair of hearing aids for $440 that met his needs.

10/10 for effort there. Electronics can be wonderful.

Similar story to mine - but mine (good old NHS) were free. His budget level aids would give a much better experience than one with fixed microphones because of the directional information (and discrete construction) of a pair of tiny aids, right on the ears. I still get confused by (particularly) birdsong, though.

 

[Laroxe]

It's a mistake to think that the hearing aids used in the NHS are not particularly good, and in fact many private providers use the same models. The ones made available depend on your local NHS provider, like many things in the NHS they are bought after negotiations with the manufacturers and contract agreements, this means they get them cheaper than a private individual would pay.
The hearing assessment allows them to match the amplification to the hearing loss and the aid can be adjusted over time, the initial assessment of hearing loss tends to be more elaborate and follows an assessment by an ENT consultant. Once they know the type of hearing loss they are dealing with, the way change, ect. is assessed will match the information they need. Unfortunately, in age related hearing loss the changes tend to be progressive and fairly predictable, the assessment is simply a way of monitoring the changes and optimizing the aids settings. While there are some attempts being made to understand, modify or even reverse age related hearing loss, progress seems to be painfully slow.
They tend to use behind the ear types, which tend to offer more features and better performance than the small in ear aids. I suspect that the main reason many people buy privately is for cosmetic reasons as the NHS only provides the small IC aids in particular circumstances The current ones used usually offer a number of quick change settings that can be selected for different situations, they can use loop systems and may be blue tooth enabled. This means they can be used with a range of other assistive devices.
You really need to know the model you have to get all the specifics on performance, but we have to recognize that the current technology still relies on our sensory apparatus and has some serious limitations.
I think your caution is appropriate, it's true that the most expensive aids available can offer some improvement, but whether you would be aware of these improvements is debatable. There may be all sorts of other issues that might add to the cost and the NHS provides free continuing support
Remember that the NHS audiologists are not paid by the aid manufacturers and are usually more than happy to discuss what is available and offer advice.

 

[sophiecentaur]

@Laroxe thanks for those comments; it's always good to hear from someone who knows the business.
From what you say, I wonder about what the possible improvements could be, beyond equalisation and perhaps some limiting / compression to protect from high levels, without complicated tests of the subject's hearing.

The tests I have been given have (appear to have) done no more than finding the frequency response at low level (threshold?). I can't believe that is all that the sophisticated aids compensate for. The 'deep neural network' AI function is claimed to decide for itself what the relevant content of the incoming sound is and then apply the most suitable compensation process. It would need some 'score' from the user to indicate how well the device is doing. Does that mean input via the smart phone whilst the device is learning about the user's ears?

Unfortunately, all that one can read from a brief search consists of sales talk (just like with a car with CD stereo, heated seats and classy colours etc.) and some (could even be snake oil) descriptions of what the devices can do. A 'memory' of thousands of common types of sounds which can identify what knobs to adjust sounds very attractive as long as my £3k+ actually achieves something worth while. Google may be very clever but there's no such thing as a free lunch when it comes to serious searches for tech information. There's always a gigantic leap from sales to serious technical info. I'm after some informed opinion and to learn of the possible pitfalls.

As I have already commented, the situation with and without my present aids is pretty damn impressive and it may involve diminishing returns.

I have booked in for a visual inspection of my ears and a check on my present aids. Then I expect a test, in due course. You have made the point that the NHS audiologists give disinterested advice and that has to be a good thing. I guess if the person who tests me is enthusiastic enough to keep abreast of the state of the tech then they will give the sort of advice I'm after.

 

[Laroxe]

I suspect that the information you are looking for isn't readily available for a number of reasons, many of which are because companies tend to invent their own labels to describe certain features. For example Oticon, a major producer describe features such as BrainHearing technology, SpeechGuard E, and the OpenSound Optimizer, other companies might describe the same general feature differently making comparisons difficult.

I thought that there are some principles to consider in choosing aids, I don't think its possible to think of their being a best, it always has to be, best for that particular person. The aids supplied by the NHS are generally considered to be a match for good quality mid-range priced aids, the most expensive often do offer extra features, but the technology changes quickly and tend to become available to most aids quite quickly. I suspect that any advantages offered by the technology will have a limited “lifespan” and aids tend to be updated anyway about every 4-5 years.

Even price comparisons are not as helpful as they might be, for privately purchased aids people are buying a package which includes after care and not all of the features may be needed, for example a rechargeable aid costs more, for others an iPhone is needed to access some features. Judgements about the sound quality are always subjective, and the incremental improvements over time tend to be getting smaller. Some of the developments, like the increasingly sophisticated use of AI certainly sound interesting, but I simply don't know how useful this is.

Another issue in terms of cost is that the NHS enters into contacts with suppliers and buys a significant number of aids, this means that they pay significantly less than a private buyer might. The companies are aware of this and their marketing literature describes developing particular aids to specifically match the needs of the NHS and which are not available to private buyers, in reality this is most likely a way to control the market prices.

The ones available on the NHS depend on where you live, but I still think talking to the audiologist is the best starting point. They are generally very well-informed, that's their job and most clinics are also linked to training Universities, having to supervise students is a powerful motivator to stay well-informed.

I'm waiting for my new aids and despite a lifetime in healthcare and teaching I simply don't try to keep up with the technology, even if I wanted to, like you, I've discovered how hard it is to get some of the information. Personally, I think it's unlikely that buying privately would offer any significant advantages, but I am aware that aids are increasingly becoming part of the multifunctional technology world that surround us. Some are already becoming health monitors rather than just hearing aids.

This is an American site which offers a brief introduction to the technology

https://www.healthyhearing.com/help/hearing-aids/technology

and this one tries to identify the best.

https://www.ncoa.org/adviser/hearing-aids/best-hearing-aids/

There is a description of the Oticon technology which might be useful, but more likely not, at

https://www.hearingaid.org.uk/heari...s-brain-hearing-technology-helps-hearing-loss

 

[sophiecentaur]

companies tend to invent their own labels to describe certain features. For example Oticon, a major producer describe features such as BrainHearing technology, SpeechGuard E, and the OpenSound Optimizer, other companies might describe the same general feature differently making comparisons difficult.

This is the problem. However, I'd bet that companies producing such highfalutin' equipment (and companies that source it) would have been doing extensive subjective tests with real people with real ears and somewhere there should be some serious data about percentage improvements etc. etc. I'm talking about the sort of published research work that is done on stereo and binaural stereo etc.. I took part in several tests (as one of many lab rats) and the results were good quality.

I imagine that there is so much money at stake that this sort of information will be hard to get hold of. 'Reviews' are full of information about rechargeable batteries but I would willingly carry around my own power source in my pocket if the 'In Ear Receiver' would actually do something to improve my hearing.

Still, I am 'on it' and had my ears looked at in this morning. I have to put oil in one and get them looked at again and then I will be given a repeat hearing test. I was a bit disturbed that the audiologist didn't seem aware of a test that I had in the not too distant past but no matter.

They are generally very well-informed, that's their job and most clinics are also linked to training Universities, having to supervise students is a powerful motivator to stay well-informed.

I'm not so sure that applies to the services in my local Community hospital. It's easy to get an appointment, though so things aren't that bad. The most technical statement I heard was "makes your hearing better".
Thanks for the chat.
I'm in it for the long haul . . . . .

 

[TonyStewart]

Anecdotal info FWIW

I had always imagined that if I was hard of hearing, that I would just use wired ear buds and a Walkman to listen with good stereo cardioid mics from an old Sony reel to reel tape recorder. Then have a lapel mic to suppressed the earbuds from my own voice. Our skulls do the same with opposite phase channel mixing to the ear drums. Electret mics attempt to cancel out distant sounds with the open back . I would have all the tone controls of a Graphic EQ on the walkman to tune for the best sound. Electret mics in old webcams with an enlarged pinhole are very sensitive to distance sounds, but not as high quality as magnetic mics. So that's a personal choice.

It might take some effort to design this but the materials are common and cheap.

Up or Down-conversion of the spectrum or tone shifting is available on Audacity to shift the spectrum but only on recorded or generated sounds.

A compander can compress or expand with various attack/decay rates to accentuate and attenuate desired effects. If these improve SNR of voice by 6 dB this reduces error rate of voice recognition significantly or several orders of magnitude.

Listening to self and others can be different. Like wearing a headset.

My wife had fluid in her left skull bone which followed a left ear infection then 3mos later meningitus and 3mos of antibiotics. The fluid still degrades her s11 and s21 parametric response meaning her sidetone or own voice was 20 dB louder. But at least the CSF is not infected. Her left hearing was 30 dB down so her voice reduced naturally as her own voice was louder, then I couldn't hear her. I calibrate my ears with Audacity and a swept frequency on good speakers, but a credit card or a finger swipe on the skin is a (cheap N dirty) quick-test of white noise test for comparing left/right response and even calibrating levels of Tinnitus.

 

[TonyStewart]

Down-conversion of spectrum is not a great enhancer. I tried 50 % and I sounded like those movies with people acting as disguise their voice (poorly.) Then tried 15% down shift and it can't say it sounded easier to recognize. on a log scale -15% shift of f is 1% of the 3 decade spectrum, so this is not helpful

Communication Theory dictates the way to optimize detection or discrimination is always match the filter to the energy of the signal for passband and block the filter spectrum that is noise. This usually means a high pass filter. with 20 to 40 db per decade. You can see my near-field voice is concentrated between 100 and 800 Hz, yet "s's f's and sh's demand more gain the in the 3 to 7 kHz band for detection.

If one cannot hear well past 6 kHz then the sss sound will be diminished and sound the same as the ffff sound. which is last upper white noise on the lower plot.

 

[sophiecentaur]

Our skulls do the same with opposite phase channel mixing to the ear drums.

There is a very clever mechanical structure in the Middle/inner ear interface. There are two 'windows' (diaphragms), one is in contact with an ossicle and the other is free. It is the difference between the two pressures that is processed by the cochlea.

Vibrations in the head vary the pressure in the middle ear and affect both windows in an identical way. The 'difference' is zero and it's only vibrations of the ossicles that get through. Those ossicles are a great example of an impedance matching transformer. Plus clever noise cancelling. The simpler image shows how the two sets of vibrations are processed an it's along the lines of an Op Amp with good common mode rejection. A blocked Eustachian tube can produce excess common mode signals and the cancellation no longer works - sounds unpleasant and alarming. This basic idea will be pretty familiar to an EE, as would be the use of dB and the concept of using numbers to describe performance. At the level of information I have found, there's not a lot of that!

 

[sophiecentaur]

@TonyStewart interesting details there. However it's the actual perception that counts and I would really appreciate some digest of figures about how much hearing is actually improved under a number of different conditions with representative aids. A few scattergrams of test results would establish some level of cred to back up the sales talk that I come across everywhere.

I would really have appreciated having a repeat hearing test (simple tone burst squeak) whilst wearing the aids I was given. That's just Good Engineering afaics.

DIY versions of hearing aid shave a big disadvantage because they are too cumbersome to wear all the time and microphones need to be attached to the head for directional information./

 

[TonyStewart]

Normally mic's can be worn with clip-ons or attached to a hat. Hearing analysis technicians know how to equalize and compress/expand voice so as not to cause background fatigue and increase SNR the way I said. up to 8kHz.

Then they use a list of 100 words at low levels in a quiet room to determine the threshold of error-free with lots of similar sounding words. If you try Headphones and a stereo cardioid mic with treble boost and self control of volume, this would be the simplest test for proof of concept. Although our two ears are 3D so we can tell front/back.

 

[sophiecentaur]

Normally mic's can be worn with clip-ons or attached to a hat.

This is fine for an interesting experiment but you surely can't be suggesting that people would want to walk around all day with wires dangling etc. I don't have any hangup about my poor hearing but discrete HAs actually help interaction with other people because they are unlikely to see them and get distracted. Not many folks want to wander round looking nerdy or 'an enthusiast' and, to be at all suitable, any solution needs to be appropriate for all situations i.e. much like existing models in fact.

If you try Headphones and a stereo cardioid mic with treble boost and self control of volume, this would be the simplest test for proof of concept.

Which concept would it prove? A manual volume control in the top pocket is something that 'old folks' used to battle with to avoid embarrassing howl round - in the 50s. I already know that basic HAs (of the free to NHS user kind ) give (me) very good results. Mine have switchable directivity (sort of omni and cardoid choices) and that sometimes works fine. Feedback is suppressed pretty much always and no-one but me can hear it. So I guess all the reasonable tests have already been carried out - which is why even the cheapest models are still not cheap to buy privately. I think this particular wheel has already been invented.

 

[TonyStewart]

I apologize for my naive anecdotal opinion. I have some audiology experience but nothing like those here which expertly opine modern solutions. https://www.ncoa.org/adviser/hearing-aids/best-hearing-aids/ where they have the experience and offer a dozen best categories. The ambient noise types for each situation that uniquely define the denominator in SNR determine the technology required to improve error rate in communication. The SNR threshold for discrimination at a defined error rate follows some curve for SNR vs Error rate. I have used these in my test experience in electronic communication and BER test set design and magnetic recording test experience for HDD's in the 80's.

Companding the signal with a matched filter to the signal spectrum has always been my best understanding and a method that I used when designing an amplifier for throat mics used by jet pilots. My relevant initial experience was in the late 70's designing an intercom for a noisy air suit used in reactor building eddy current testing. I chose to design a compander intercom with throat mics which detect about 3 kHz BW and I used pre-emphasis with fast attack expand and slower decay for the VOX amplifiers with a matched filter. It seemed to work well in extreme white noise environment.

Good luck in your search.

https://www.ncoa.org/adviser/hearing-aids/best-hearing-aids/

 

[sophiecentaur]

I apologize for my naive anecdotal opinion. I have some audiology experience but nothing like those here which expertly opine modern solutions.

Sorry if I've been a bit short with you but it's through frustration. I respect tha you have a lot of design experience but nearly everything else I have read is very light on technology and actual results and heavy on the delights of ownership of a £3k box. I did enjoy what you had to say but your comments don't really address my particular problem.

There is no way I would want or be able to construct a piece of electronics that you describe, any more than design and build a smart phone from scratch. I am looking for a good reason to spend cash on improving my hearing experience. What I had been seeking is a measure of actual performance.

Actually, having had my moan, I did some more searching last night and came across this link. It describes a pretty comprehensive survey of user experiences and concludes that, in many cases, the posh ones are very little better than the basic ones. This may be a bit unfair the posh ones because, once left to themselves, many of the test subjects don't get a lot from the advanced HAs. But that could be the same as expecting your average Joe to get a lot more out of the very highest spec laptop when he's quite happy with a cheaper machine. But, 10/10, there was a lot of graft put into the study and results seem to have been analysed pretty thoroughly. There is other stuff in the PubMed universe that could also be of use to me.

I'm being a bit difficult here because I'd find it a challenge to get the very best out of a £3k pair and I would tend to ignore the results from non-tech users (as with most electronic and information systems). To be honest, I was rather hoping that a number of PFers would have answered my query to say that their new HAs are fabulous and the best few k's worth they ever bought.