High Fidelity Stereo Hearing Aid  - Page 1
Forum section: electronics / general

author: jonovid
author_rank: Super Contributor
timestamp: June 10, 2025, 10:15:20 am
content: does it exist? if not why not? would it work?High fidelity stereo hearing aid set for listening to music.with dynamic frequency bandwidth compression to compensate for age related hearing lossso 20Hz to 20KHz is compressed to say 50Hz to 12KHz. for aging audiophiles.only the top and bottom of the frequency range would be compressed. or moved up or down.the middle of the frequency range would be uncompressed.most hearing aids are way too expensive and trade fidelity for compactness. need two for stereowhen what is needed is High Fidelity Stereo frequency compression that fits the frequency range into the age related hearing of the user.or is there a phone app for this? you would need two microphones spaced or separated by 15cm with artificial ear lobes.as phones do not have two microphones spaced or separated by 15cm.anyone can DIY a cheap mono hearing aid for Lo-fi .

author: tggzzz
author_rank: Super Contributor
timestamp: June 10, 2025, 10:37:36 am
content: Quote from: jonovid on June 10, 2025, 10:15:20 amI doubt you are deaf? If you were then you would be content to be able to hear speech well.Are you aware of just how non-linear (in every dimension!) the ear-brain combination is? Consequences: that's why MP3 encodingcanwork, and why linear hearing aid responses are not far from being irrelevant."20Hz to 20KHz is compressed to say 50Hz to 12KHz ... only the top and bottom of the frequency range would be compressed. or moved up or down" makes no sense. What frequency should a 15kHz be? How would you preserve the vital harmonic relationships within an instrument's note? Include phase as well as amplitude. I suggest you take an audio stream of a simple instrument (e.g. piano, recorder, trumpet, drums), use a signal processing package to mutate the recording as you suggest (but use lower frequencies to make the consequences easily audible), and see if your concept works.Modern hearing aids are extremely complex, withmanytweaks to the frequency domain and to ensure they don'tfurtherdamage hearing.Hearing aids absolutely must be matched and adjusted to the individual's hearing loss. That requires equipment in a soundproof location plus time and expertise to measure. Then the relevant hearing aid has to be acquired; keeping a stock is not practical. Then each aid has to be fitted, its frequency response adjustedrepeatedlyuntil it matches both the hearing lossand the shape of the ear canal. That all requires more specialised equipment and time. Then it has to be re-adjusted after being used for a couple of weeks. More time and expense. Conclusion: the cost of a hearing aid is trivial compared with the other costs, costs which cannot be avoided.Don't forget the costs associated with being able to demonstrate that any new type of hearing aid won't cause harm.Don't forget another prime requirement: low power consumption, so the small and light battery lasts a tolerable time.

author: aeg
author_rank: Regular Contributor
timestamp: June 10, 2025, 10:54:08 am
content: Quote from: jonovid on June 10, 2025, 10:15:20 amIn the equal tempered tuning, an A-major chord is 440Hz, ~554Hz and ~659Hz. The latter two notes are ~1.26x and ~1.50x the root note, which is very close to the integer ratios 5/4 and 3/2 that sound the most harmonious. After your proposed transformation, the chord would be ~301Hz, ~369Hz and ~432Hz, or ratios of ~1.23x and ~1.44x. These intervals, especially ~1.44x for the perfect fifth, are far enough away from integer ratios that they would tend to sound dissonant. A voicing that includes the octave would be even worse - ~1.87x instead of 2x.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 10, 2025, 12:31:51 pm
content: Totally agree: the music will end up dissonant -farfrom hi-fi.I wonder how it would sound if every frequency above 10kHz (say) were halved. Harmonic relationships ought to be preserved, I think. It would be fun to design the DSP algorithm.

author: Marco
author_rank: Super Contributor
timestamp: June 10, 2025, 12:38:04 pm
content: Apple is slowly taking over low hanging fruit like that. Samsung tries to catch up, but never quite managing because they just don't have the same ecosystem profits to buy up patents and companies ... the advantage of complete monopoly over an entire consumer electronic ecosystem.So what I'm saying, Airpods Pro 2.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 10, 2025, 02:29:04 pm
content: Quote from: jonovid on June 10, 2025, 10:15:20 amDepends on the hearing loss. For a modest loss, using a standard earpiece and some amplification might do, although even for this simple purpose, you'll need to handle compression and frequency compensation, and so there is some signal processing to do for sure. Otherwise the result will be unbearable.A real hearing aid, for more severe hearing loss? No. Your first hurdle will be to source an appropriate transducer. They are usually not available off-the-shelf from Digikey.The second will be to make a earmold. Earpieces for hearing aids go relatively deep inside the ear canal and require a proper earmold, otherwise it won't fit and will not be as effective, as well as probably cause damage/inflammation/infections.Regarding stereo, people with bilateral hearing loss can wear two hearing aids. That's of course twice as expensive, but that's not something unusual at all.Regarding "audio quality" of modern hearing aids, do you have even evidence that music doesn't sound good with a properly fitted hearing aid(s)? They do a pretty good job these days.Now the idea of designing an "open source" hearing aid has already been explored and I remember of one such project, can't remember its name right now. But that's a pretty significant endeavor.

author: Analog Kid
author_rank: Super Contributor
timestamp: June 10, 2025, 11:21:12 pm
content: Why compression, which as has been pointed out can have harmful effects on the resulting sound?Why not just judicious low- and high-pass filtering? After all, that's essentially what age does to our hearing (and I'm willing to bet that most of the loss is at the high end, not the low end). Possibly with a gradual HF boost.

author: mazurov
author_rank: Frequent Contributor
timestamp: June 10, 2025, 11:22:39 pm
content: Quote from: jonovid on June 10, 2025, 10:15:20 amRealistically, it's more like 1-3 kHz - if that. A modern approach involves measuring the ear’s response, identifying the (very narrow) frequency window where it can still detect sound, and then tuning the hearing aid to operate within that range. The result is far from normal audio, often resembling the sound of an acoustic modem handshake.

author: jonovid
author_rank: Super Contributor
timestamp: June 11, 2025, 01:24:35 am
content: more google searching dug up this- frequency shifting hearing aids.https://hearingreview.com/practice-building/practice-management/linear-frequency-transposition-extending-the-audibility-ofhigh-frequency-informationby compression I meant the frequency bandwidth outside the age related hearing of the user not just volume levels with in it. with a audio equalizer

author: tggzzz
author_rank: Super Contributor
timestamp: June 11, 2025, 09:52:59 am
content: Quote from: jonovid on June 11, 2025, 01:24:35 amInteresting; I haven't come across that concept. It appears to only be applicable for limited forms of deafness, and many of the (small) trial participants appear to turn off the facility. I still see no way in which your concept would be useful for music.Where the deafness is caused by the cilia falling off, a cochlear implant is probably a more complete solution.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 11, 2025, 10:58:41 am
content: Quote from: jonovid on June 11, 2025, 01:24:35 amAh, that's interesting. It is exactly what I threw into the ring a few posts ago where I suggested "halving" the frequency. I had no idea whether it was technically feasible, but it seems it is. I'm still most intrigued to hear the effect it has on speech and music.

author: Halcyon
author_rank: Unknown
timestamp: June 11, 2025, 11:03:47 am
content: I don't know the technical details but a lot of modern hearing aids connect via Bluetooth to a smartphone, to be able to adjust them for certain conditions. For example, noisy restaurants, versus watching television. They offer all kinds of EQ presets, noise cancelling, amplification etc...Many modern smartphones also support telecoil induction loops, and hearing aid compatibility, in addition to regular Bluetooth hearing aids.

author: tggzzz
author_rank: Super Contributor
timestamp: June 11, 2025, 11:07:30 am
content: Quote from: SteveThackery on June 11, 2025, 10:58:41 amFrom the diagrams it appears, but isn't certain, that it is a simple translation of a frequency band, as happens in a mixer. That would not preserve harmonic relationships, and hence music would be significantly changed.Given that the principal requirement with severe deafness is to restore the ability to comprehend speech, that would not be a major impediment.Assessing the hearing loss would require considerable expertise, equipment and time.Those are incompatible with the OP's statement "most hearing aids are way too expensive and trade fidelity for compactness". I believe it would be both expensive and not high fidelity

author: SteveThackery
author_rank: Super Contributor
timestamp: June 11, 2025, 11:11:31 am
content: Quote from: tggzzz on June 11, 2025, 11:07:30 amCould you explain that? As I see it, halving the frequency is just shifting it down one octave. So wouldn't that preserve the harmonic relationships?

author: tggzzz
author_rank: Super Contributor
timestamp: June 11, 2025, 12:16:03 pm
content: Quote from: SteveThackery on June 11, 2025, 11:11:31 amExample: a 9kHz-10kHz band would mix down to, say, 500Hz to 1500Hz.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 11, 2025, 03:40:19 pm
content: Quote from: tggzzz on June 11, 2025, 12:16:03 pmNo, I'm talking about halving the frequency. So 9kHz to 10kHz would become to 4.5kHz to 5kHz, so one octave lower, which I think should maintain the harmonic relationships.I agree that if you mixed down, rather than halved, you would get discordance.It is only now becoming clear to me that mixing down and halving are very different. Mixing down slides an entire frequency range down, as @tggzzz says, maintaining its width. Halving halves the frequenciesandthe width.

author: tggzzz
author_rank: Super Contributor
timestamp: June 11, 2025, 05:35:51 pm
content: Quote from: SteveThackery on June 11, 2025, 03:40:19 pmBut a 3kHz fundamental would have harmonics in "odd places".There's also the issue of matching phase relationships, which are used to indicate direction at low frequencies. What that would mean for a scheme like yours is anybody's guess. Even in good working order, the ear-brain combination is non-linear in all every way, and then add the individual's imperfections.

author: tooki
author_rank: Super Contributor
timestamp: June 11, 2025, 06:12:38 pm
content: Quote from: jonovid on June 10, 2025, 10:15:20 amThat’s a bold, somewhat condescending statement. How do you know it’s true?My best earbuds (ones expensive enough to usually be called “in-ear monitors”) are also my smallest. Like most hearing aids, they use balanced armature drivers, which are very compact. They’re made by a company whose roots are in audiology, and they’ve got very flat response across the entire adult audio spectrum. So compactness need not mean low fidelity.And what makes you think heading aid manufacturers don’t care about fidelity? I wouldn’t be surprised if a lot of the engineers who work on them are themselves audiophiles, on account of their deep knowledge of sound and of audio hardware.Do you have any clue what modern hearing aids actually do? They aren’t little dumb amps. There’s a shocking amount of technology packed into them, from multiple mikes and drivers, to the power amps, radios and power supply, and powerful DSPs that allow them to eke out every bit of clarity the patient’s ears are capable of. They have highly tuned noise cancellation, with various modes for different environments and situations — including listening to music, both ambient and direct via Bluetooth.Quote from: jonovid on June 10, 2025, 10:15:20 amAnother overconfident statement: how do you KNOW this is what is needed?Quote from: jonovid on June 10, 2025, 10:15:20 amWell, every iPhone made in the last 10 years or so has at least three mikes, two of which are indeed around 15cm apart. I assume Android phones are similar. The bigger problem is that they aren’t located where your ears are, i.e. they’re pointing somewhere else altogether, or are in your pocket.Quote from: jonovid on June 10, 2025, 10:15:20 amOh really?Do you even realize that a big part of what hearing aids do isn't to amplify sound, but to filter and tweak it for the individual patient? It’s been many decades since a typical hearing aid was little more than an amplifier.

author: tooki
author_rank: Super Contributor
timestamp: June 11, 2025, 06:20:39 pm
content: Quote from: Marco on June 10, 2025, 12:38:04 pmI bet Apple has had actual hearing aid engineers on its earbuds team for years. As they added more and more processing power and microphone arrays to them, it must have become obvious that, from a hardware standpoint, they had more than everything needed for some hearing aid functionality. But actually seeking and getting FDA approval for the AirPods Pro 2 was quite a coup.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 11, 2025, 07:04:23 pm
content: Quote from: tggzzz on June 11, 2025, 05:35:51 pmBut so would a 1.5kHz or 6kHz fundamental.My main interest is whether it could even be done, and how, and how it would sound. I'm certainly not putting it forward as the solution. It's just something that might be interesting to explore.

author: tggzzz
author_rank: Super Contributor
timestamp: June 11, 2025, 07:28:32 pm
content: Quote from: SteveThackery on June 11, 2025, 07:04:23 pmIf it works - and I'm prepared to be generous in the interpretation of "works" - then I'm interested too.I note that POTS was more than adequate for speech, and that is 3.4kHz upper limit. That indicates the higher frequencies contribute little to hearing speech, which leaves the benefit of including higher frequencies as hearing music.I'm skeptical that it will sound natural, which raises the question of to what extent it is possible to treat old dogs new tricks.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 11, 2025, 08:11:06 pm
content: Quote from: tggzzz on June 11, 2025, 07:28:32 pmYes, indeed, although I think 3.4kHz was a bit too low. The fricatives, especially 'f' and 's', are difficult to tell apart when there is insufficient context. Still it allowed for 8000 samples per second digital encoding, 32 channels in a 2Mbps pipe.