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Why has the hearing aid industry gone completely digital? (slate.com)
50 points by daddylonglegs 34 days ago | hide | past | web | favorite | 72 comments

Digital technology may offer advantages in its ability to tailor amplification to a particular individual’s loss profile as well as the availability of programmed settings for different social situations, plus extra bells and whistles like Bluetooth and app-tracker options. What it cannot do is faithfully reproduce natural sound in a way that is subjectively satisfying and moving and true.

Oh buddy do i have a xiph rant for you. I am more or less entirely willing to chalk this up to what I shall politely call “top-down effects”.


Frequency tuning and rapid readjustment of it is the key feature of modern hearing aids and we’re just barely scratching the surface of what we can and should do.

Here’s why: presbycusis, or age-related hearing loss, has a cruel fact about it. As the threshold of audibility rises for a particular frequency, the threshold of pain lowers. Rather often, the reason people don’t use hearing aids is that they create a situation in which you can hear but also every sound is painful!

Precise digital control of per-frequency intensity amplification can make that a lot less terrible. If it hurts to hear at 4khz, we can squelch that frequency but boost the 100-400hz range and your speech audibility should still get the boost you need to talk to your grandchildren. Throw a BLE connection to a nice multicore GPU smartphone into the mix and we can start offloading really complicated processing to the thing in your pocket.

I love that Xiph rant and have it bookmarked.

> Throw a BLE connection to a nice multicore GPU smartphone into the mix and we can start offloading really complicated processing to the thing in your pocket.

In principle yes, but latency is the nasty problem in this scenario. The wearer is still hearing some ambient sound in addition to processed sound, and if processing latency is greater than about 10 ms (IIRC) it drives the listener nuts and they won't wear the aid. The problem with smartphones is they have too many layers of general-purpose OS cruft sitting on top of the A/D and D/A. I've read that IOS is better than Android in this regard, but for lowest latency you really need a dedicated realtime processor and a realtime OS.

> if processing latency is greater than about 10 ms (IIRC) it drives the listener nuts and they won't wear the aid

For context, sound travels about 3.4 metres (11 feet) in 10 milliseconds. Of course, this is added to the time taken for the sound to reach the microphone.

Our brains apparently correct for this sort of lag without us noticing, but maybe (I have no idea) this correction is calibrated to perceived distance.


Can you really offload per-packet processing to a connected Bluetooth device without injecting a frustrating amount of latency? Bluetooth isn’t known for being a fast protocol

I know it’s being tried. Good question, though. I can’t imagine it’s super easy, and maybe some other protocols are in the mix.

The obvious stopgap measure is the neck-torc approach. Offload computation to a bespoke thing and use an app for tuning, or the like.

I'd be concerned about battery life. Those tiny batteries are expensive, and changing them is a challenge, especially if you have the vision and dexterity problems associated with age.

How do Bluetooth headphones compensate for the latency?

I haven't seen them compensate successfully for anything real-time (games).

I've seen them compensate for things like movies; I assume they send Audio ahead of time, and "hold" back the video until it's in sync.

In my experience, they don't; if I'm typing on an iPhone there's a noticeable delay between me tapping a key and hearing the sound in my QC35s.

That's not the bluetooth latency you're hearing, that's just how active noise cancellation works.

QC35s buffer about 75ms worth of ambient noise and then phase-invert it and play it back. This destructively interferes with the outside noise, and cancels it. But you have to sample your environment on some time window to get it to work, so when ANC is on, there's lag. This is also why ANC only works well for slowly-varying noise like airplane drone, but can't handle impulsive sounds like gunshots.


Interesting, thank you!

Apple uses a special chip, the W1 or H1 to resolve syncing issues. But that wouldn't work well for these situations as they cant control the visual syncing of a live person.

There are also lower latency bluetooth codecs. I use LDAC with my headphones on my computer, and I don't usually notice any latency.

How are you using LDAC with a computer? Windows and macOS don't support it, there's some fork of pulseaudio that has it for Linux but I never figured out how to get that working.

Just to expand on your comment, I don't think there is an analog hearing aid that has a working solution for the "cocktail party effect". There are several advantages to digital hearing aids.


Would it be possible to shift/autotune the painful range to a different range, to preserve input while reducing pain?

> What it cannot do is faithfully reproduce natural sound in a way that is subjectively satisfying and moving and true.

Gahhh. This just makes me want to cry.

Look, sonney-me-lad, you might want an analogue amp in your ear, that has a terrible frequency response, is prone to feedback and will most likely destroy what frequency range you have left, but lets not blame this as a technical problem. (don't start me on battery life)

You like the "warm" sound of "analogue". Hand in hand with this claim, is that somehow one can have the ability to tell digital recorded sound from analogue. As an ex recording engineer, I can tell you, you're full of crap. I could[+] make a very convincing "analogue" sound using a mackie D8b digital desk and 24 track digital recorder.

I can tell you now, that if I played a cd, housed it in a box that looked like it had tube on it, then attached a record player, Piped it into a decent amp with some NS-10s. It would sound great. To convince you of course I'd need to clip off the top frequencies, (8k+) add some clicks and hiss (raise the noisefloor) you'd then be espousing the wonders of its "warm analogue sound".

Why have digital hearing aids concurred the world? because they are better. One can steer the microphones, they use less power, the frequency response is trivially tuned to your hearing range, there are limiters in there to stop damage, The speaker can be calibrated, as can the microphone.

you can add a directional handheld mic so you can point it at people so you can hear them talking. You can add background noise reduction trivially.

All of this can't be done with frankly shitty analogue hearing aids.

Don't fuck up other people's lives with your nonsense.

>clip off the top frequencies, (8k+) add some clicks and hiss (raise the noisefloor) you'd then be espousing the wonders of its "warm analogue sound".

You know, you may have a product idea there. Not so much for hearing aids, but as a standalone device.

My dad explained to me that his hearing loss is dominated by his inability to zero in on conversations in a crowded room. That has made it so that he’s much less willing to go out to socialize in restaurants, because that environment creates a form of isolation brought on by his hearing loss. While his hearing aids certainly do help, I would argue that they haven’t gone digital enough.

Being able to audibly isolate a speaker in a room full of other speakers would be a boon for his case (and I would presume many others). Anyone on HN working in this area?

Speech enhancement (denoising/dereverb) and seperation is absolutely a hot research topic, as it's needed for fields like voice assistants as well. Unsurprisingly, the state of the art is variety of deep neural networks, here's a good overview of recent developments [1]. Of course, many of these are far from real time, but earlier techniques are used in some digital hearing aids iirc. Apple have also released [2] some details of the system the Homepod uses, along with audio samples.

A quite interesting further development of these is this paper [3] which uses brain activity to determine which particular speaker the listener is trying to hear, and then optimises that.

[1] https://arxiv.org/abs/1708.07524 [2] https://machinelearning.apple.com/2018/12/03/optimizing-siri... [3] https://advances.sciencemag.org/content/5/5/eaav6134

A pair of Sony WH1000 does a pretty good job with it's "voice mode" (which I assume is just some smart frequency filtering). I don't see why it would be that hard to make the same tech available in a smaller package.

Deep neural networks should be able to do source separation.

Imperfectly, but the results are at least passable.

Bose has a “hearables” line in this vein. I know 5 or 6 folks in their labs, and it’s sounding (hah) promising. They aren’t medical devices, yet, but beamforming earbuds are a thing now.

I expect to see full medical devices that do this in the next decade or so.

DeLiang Wang's group at Ohio State is doing great stuff for speech extraction in complex environments, as are some of my colleagues in other universities in collaboration with Starkey.

It’s coming along!

There is a lot of cool research in separating sound sources in general. From friends in the industry, I know that the traditional approach taking advantage of phase difference between microphones is hard, because the of the small separation distance (within 1 hearing aid device and even when you have one in each ear). Conversely I haven't fully comprehended it yet, because I've similarly read that Google Android's beamforming microphone tech should be quite good: https://github.com/shichaog/WebRTC-audio-processing/tree/mas...

Here are some examples of new research with neural networks https://www.youtube.com/watch?v=FMEk8cHF-OA og https://www.youtube.com/watch?v=zL6ltnSKf9k

Most restaurants also seem to be much louder now than they were 20 years ago. They're so loud even people with good hearing have trouble having a conversation. I worry that just going to a popular restaurant nowadays is damaging my hearing, and I'm starting to avoid the loudest ones.

As costs go up and fashions change as does the interiors of restaurants. Gone are the "soft" things like plants, carpets, dropped ceilings, and plush furniture. More common these days is hardwood, cement, steel, glass, and exposed ceilings.

It's no coincidence that louder often means spending more on drinks and quicker table turn overs. So the noisy places are out competing the quieter places.

Sad, I find about half and 75% of places are unacceptably loud during normal peak hours. Fortunately google displays how popular a place is (if often varies by business) so I can go off peak.

My Airpods have a mode where you can use them for directional hearing. You can set the iphone next to the person speaking and whatever it picks up is transmitted to the airpods. It would be nice for hearing aids to be able to wirelessly connect to a directional mic for situations like this.

His hearing aids can already connect over BT. He uses it a lot to watch TV. But I just checked and there seems to be a bunch of apps on the App Store that do some variation on this idea. Something to try out with him on my next visit home. Thx for the idea!

This is sometimes called the “cocktail party problem”, or more formally “Blind Source Separation”. It’s tough, especially with one or two sensors. You’d also need a fairly unobtrusive way to choose the source, which is also tricky.

That said, I had a classmate with a hearing impairment. His device had a tiny wireless microphone that preferentially fed his hearing aid (I.e., he could hear other stuff too, but the mic was loudest). The teacher usually wore it, but it would be given to you if you were working with him on something. It was certainly a little clunky, but it did seem to help him a lot. Perhaps something similar could work for your dad?

Unfortunately, I have no idea what the device was called—and it was a long time ago- but maybe this is enough of clue for his audiologist.

That’s a cool idea. I wonder if a phone could be that device in today’s world - something you would bring out and drop onto the table to act as another set of microphones and perhaps more importantly, a lot more compute power?

I’ll pass that tip along to him. Thx!

When was the last time your dad tried a newer hearing aid? Some now have multi-directional microphones that are meant to solve for the use case you described. They've been getting some good reviews, and with the recently de-regulation expect the pace of change/competition to get more fierce.

Pretty sure he bought his last one at Costco ... a year ago? It’s frustrating because adjustments require trips to his audiologist and he often complains that it doesn’t seem to improve things much. It would be great to have one that enabled self-tuning, but can also understand why that could be a terrible thing for some people.

Self fitting is definitely an option - check out this link: https://forum.hearingtracker.com/c/hearing-aid-self-fitting-...

Alternatively, let me know and I can walk you through the process.

I recall hearing (so take this with a grain of salt), that part of the issue is when you start looking your hearing you stop exercising the skill of focusing on a single stream of sound, such that when you get your hearing back you ability to do it has greatly diminished.

Yes, directionality is an issue. But the brain post processing portion has also dwindled.

So i guess getting a hearing aid sooner might be a good approach?

Is that a problem of focus or hearing?

As far as I understand it, the latter provides information needed for the former. It's possible to have deficits in either or both:

1) Hearing loss in specific volume/frequency notches instead of loss strictly at the high/low end (sometimes referred to as "hidden hearing loss", which is more a statement about the capabilities of routine screenings than it is a statement about the nature of the hearing loss)

2) Deficits in attention regulation, which are seen in numerous conditions (most obviously ADHD, but also autism spectrum, PTSD, traumatic brain injury, schizophrenia and "schizophrenia-like" conditions, and some forms of dementia)


It’s actually hard to separate the two. On the one hand, the hearing aid might not faithfully reproduce cues that let you separate different sources. On the other, “higher” brain areas can modulate early sensory areas (maybe even the cochlea) to make sounds relevant to your current behaviors more salient while attenuating irrelevant signals.

I have profound hearing loss, wear hearing aids on both ears since early childhood. I felt immediate palpable improvement when switching to digital hearing aids. Only for listening to music I switch them to "analog-like" mode (which, nevertheless still applies the 20-60dB equalizer and compressor I need). Of course some people might have opposite experience, I am not trying to invalidate anything.

The big picture is: sadly we don't really have any way to objectively measure hearing quality and its improvement due to hearing aids. We can push buttons whether we hear tones or not. We can count understood/misunderstood words. But the results don't have clear relationship with real-life hearing situations. For example, in my case, in silent room tinnitus appears which interferes with testing. And sometimes I hear better, sometimes worse.

Unlike vision, it's very hard and time-consuming to test with any repeatable/reproducible patterns, or to accurately explain to another person problem with quality of the sound.

Also, the hearing aids market is very tightly controlled by oligopoly of manufacturers and doctors. There is no way to self-adjust them. I'd very much buy user-programmable BTE package capable of 80 dB gain which I need for some frequencies. But there is plainly no such thing available without any strings attached. I have played with jackd under Linux, too, don't remeber clearly but it was problem to set the equalizer with 60dB differences.

I'm also profoundly deaf, using two BTE hearing aids as well and your comment is 100% what I'm frustrated with as well. My hearing aids are CONSTANTLY "adjusting" noisy environments for me - Usually exactly when I don't want them doing a damn thing. I'm very good friends with my audiologist, but it would take hours upon hours in her office, fiddling with all the various controls and options, to get things perfect. I want to be VERY clear too, it isn't a problem of have too many controls, that's actually an amazing benefit... The problem is that we can't reasonably expect audiologists to really spend the hours upon hours of time making minute tweaks and adjustments to capture that perfect hearing aid experience. It would just be SO much easier if after wearing them for months and I suddenly noticed my "noisy environment" adjustments were actually annoying, I could go in and make adjustments on my own.

It's also infuriating how sub-par the accessories market is. I have a compilot air 2 (bluetooth add-on) that lets my hearing aids connect to my phone, car, computer, etc. It's great, but at $300 I really expected it to work for more than a couple of hours... It also has to be clipped within 12 inches of BOTH hearing aids? My phone communicates through bluetooth across the house to my computer... Is there really no way around having to clip this dongle on the neck of my shirt? It doesn't bother me now, but damn. People in meetings and in public constantly think I'm recording them or something. Nevermind the disgusted look I've gotten at a urinal. It's just... Not ideal.

That's why you should self-fit. It's absolutely possible - check my comment below for details.

It's possible to obtain a hearing aids programmer and fitting software for it, depending on your model, but it takes some work. It's so much worth it - I'm now self-fitting and it makes up for a HUGE difference.

If you're interested, this place should get you started, or let me know and I'll assist you. https://forum.hearingtracker.com/c/hearing-aid-self-fitting-...

I have Widex Unique Fusion but don't see anything applicable in that thread.

The software you need is called Widex COMPASS DREAM: https://forum.hearingtracker.com/t/diy-self-programming-how-...

And you're going to need a wireless programmer, too. Unfortuntately, you're out of luck a little, since Widex is not using the industry standard hardware, but it's own proprietary programmer - Widex Pro Link: https://forum.hearingtracker.com/t/widex-beyond-programming/..., which seems to be available on Ebay.

Thank you very much!

> What [digital technology] cannot do is faithfully reproduce natural sound in a way that is subjectively satisfying and moving and true.

There is a one-word description of that sentence, and the word is "bullshit." It might be the case that most digital hearing aids today do not reproduce sound as faithfully as older analog ones. But it is always possible to build a digital signal processing path that is audibly indistinguishable from an analog one in a double-blind test. It might cost more or require better engineers than those who currently design hearing aids, but blaming the problem on "digital technology" is utter nonsense.

To the question:

- Smaller.

- Improved battery life.

- Better tailored to specific hearing loss (e.g. certain frequencies).

- Telecoil compatible.

- Improved Feedback Control. Better safety features.

The entire article could be boiled down to an argument that "analogue is natural, digital is artificial." It compares digital hearing aids to MP3s. The problem is, there's nothing inherently natural about the way analogue audio works, and it can manipulate and alter the sound profile just like digital (inc. compression/artifacting, particularly when space constrained/dealing with cross-interference).

Just because a technology is older doesn't automatically make it more "pure." If they argued for a way to configure a hearing aids/remove artificial filtering, that's fine (I agree), but to suggest that digital and analogue audio fundamentally work differently from a perceptual perspective isn't really factual.

There's two points here, one good one bad. The bad one everyone has already spotted; the claim that digital is inherently worse.

The good point though is the one about the industry lacking participation from people with hearing loss themselves. The "nothing about us without us" argument. Plus a sub point about the US healthcare system being expensive and not actually consumer friendly.

(Hearing aid wearer here who works for a digital audio company here! But I get mine from the NHS, so I pay nothing and expect no choice. They work well but not perfectly - the multiple sources problem is still big)

> Analog aids merely amplify existing sound—a more sophisticated version of an ear trumpet—such that there is no real interruption of the original acoustic wave.

That's just false and shows how little the author understands about audio systems. The microphone and driver in a hearing aid (and their interaction with the ear canal) alone will change the sound drastically, regardless of whether the signal processing between the two is analog or digital.

In fairness the latency of an amplifier with no filtering is less than 10 microseconds. Coherency between the amplified and unamplified signal is preserved. I’ve done some personal work on custom IEMs with ANC and the lowest latency controller I could find was the teensy. Even in the fastest round trip time you would be adding 5-10 ms of latency. Speed of sound / 16 kHz = 2 cm. A whole cycle at 2cm. If you want coherent wavefronts then low latency is essential. If the latency is fixed and less than the distance between the speaker and the eardrum (very short) then you can do some DSP tricks to fix up destructive interference.

This just happens to be on NPR today: “Untreated Hearing Loss Linked To Loneliness And Isolation For Seniors”


Another neophobe "analog is better" opinion.

They're wrong. Vinyl is back because it's hipster and other reasons, and it's in absolutely no way better.

In order for analog to be better either:

1) The (analog) filters on the hearing aids are bad. Not unique to digital.

2) You can hear more than 22KHz. I doubt it, mate. No offense but you're not young anymore, so very unlikely among an already rare population.

3) Math is wrong. Fourier analysis shows that digital doesn't "approximate" the frequencies of analog. It completely contains the exact same information.

It has gone digital because it's cheaper and allows for better custom hearing curves. Because remember there's an underlying hearing issue already.

"It turns the world into mp3" digital quality is not necessarily bad, some models might have issues, of course.

Sadly, years of 128kbps iTunes sales have ruined the idea of digital music for a lot of people.

Counterpoint: Adam Savage discussing his hearing loss and how awesome new hearing aids are.


Interesting argument but I don't buy it.

- Digital hearing aids are smaller, lower power and easier to configure than analog hearing aids (think "fits in your ear canal" vs. "you wear the original iPod on your belt")

- The benefits of full-analog audio are contentious at best and almost certainly imperceptible for people with hearing loss

If you want further convincing that A->D->A conversion is perfectly fine, https://xiph.org/video/vid1.shtml is excellent.

> Analog aids merely amplify existing sound—a more sophisticated version of an ear trumpet—such that there is no real interruption of the original acoustic wave. Digital aids, by contrast, pick up the sound, process it into binary digital information, and then reproduce the sound as a new wave using a built-in digital-to-analog converter. Digital devices thus have to re-create the activity that our brains and ears co-evolved for eons to perform. It is hubris to think that a few decades of research and development might not fall short.

Why do writers so often accuse experts of "hubris" while arguing that their own poorly informed opinion is superior to the well-informed opinion of said experts?

That said, most digital systems don't make it easy (certainly not easy enough to be relevant to a casual user) to obtain the many noise / filtering / distortion effects you get with an analog setup, and that's a legitimate complaint. While the audiophile scene is rife with placebo effects and woo, I've long wondered if some UX lessons couldn't be salvaged. Could hiss+pop+lowpass+distortion+hardware_pickiness settings be packaged into a form that would make people willing to consume them in a digital context?

Does the author actually have a reason why analog would possibly be better, other than giving consumers choice?

Is the purpose of this article anything other than to generate clicks from hipsters who will click on anything that paints digital in a negative light?

> Does the author actually have a reason why analog would possibly be better, other than giving consumers choice?

Duh no. And this article does a disservice to itself, as it looks like there could be a real issue of fidelity in the digital chain[0]. Bluetooth is known to cause issues (lag, bandwidth variations, …), and the processing chain might be problematic:

> the digital processor samples incoming sound at a rate far lower than that of an old CD player

I don't know if there's any truth to it, but it should certainly be investigated and if true fixed. It might also be that the perceptual models used in these hearing aids are not correct for, well, hearing aids.

[0] though some of the complaining could be a question of habit, the wearer's old hearing aids had a coloration to which they'd gotten more and more used, the different profile of the new ones is jarring even if it might be more correct

CD sampling is 44.1kHz. 22.05kHz is used in plenty of HAs. I haven't seen anything lower (but wouldn't be surprised to learn otherwise)

22kHz sampling isn't a problem in practice as:

- HAs focus on speech comprehension, not music. Speech doesn't high much content above 5kHz, so even 22kHz is double the Nyquist rate.

- Music is perfectly enjoyable at 22kHz (but obviously better at 44kHz)

- People getting hearing aids have hearing loss, and the majority of hearing loss is in the high frequencies

To add to this, most middle age adults can not hear above 15khz and threshold is very high at 11khz, especially if they were exposed to high sound levels in youth. Virtually no one can hear above 22khz.. if you ever hear people saying they can it is most likely bs.

People often tell stories about playing a sound or being in a lab etc. they think they heard above 20khz, but mostly likely what happened is whatever inevitable non-linearity exists in their playback chain acts as a mixer creating frequencies well in the easily audible range.

It seems clear to me the author is dissatisfied with the quality of the digital hearing aids compared to analog ones. And while this is probably subjective, the author having hearing loss probably means his reasons for writing the article are pretty straight forward.

He should write more about the qualitative differences he experiences instead of some argument referencing streaming music.

It seemed obvious to me that their complaint was about a reduced dynamic range due to (poor) digital compression, even though that wasn't explicitly stated.

That's a problem in low quality streaming music, sure, but is the author even sure it applies to digital hearing aids?

I don't know about the technical tradeoffs in hearing aids, but the other stuff in this article is breathtakingly ignorant.

There are two great videos on why this author is wrong about digital sound.



Also to add, the vast majority of the users use cell phones, and the ability to pair your hearing aids to your phone is a big deal

Because digital is a completely superior choice?

Because marketing, need something new to sell. My mother in law has worn hearing aids for years and was recently convinced to upgrade to the latest greatest as she has to have her phone on speaker and has trouble hearing/understanding when she can't see the person, eg, not in the same room but shouting. S0 €5000 ($5500) later and still has phone on speaker and still can't hear at a distance.

They went digital because "sound colors" doesn't exist.

Also: Niquist-Shannon.

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