This is basically how the first transistorized hearing aids in the 60s worked.
Zero innovation, and an implementation that wastes lots of power. Why would you use a volume potentiometer at the OUTPUT of the amplifier? It turns most of the output power into heat.
And why would you use a stereo amplifier and short the two channels together to get a mono amplifier?
You can already buy (in ear) hearing aids for less than $3 from China. A little bit more money even gets you rechargeable ones.
Also: Even in developing countries, more and more people have smartphones. In fact it might be easier to get a smartphone there than a professional hearing aid. There are apps that act as a hearing aid, taking the sound from the microphone, amplifying and filtering it, and sending it to the headphone output. Unlike with this project, the use can individually adjust the frequency response to his hearing.
Smart phones make lousy hearing aids. First the microphone needs to be in your ear for directionality, not on the phone. Second, phones don't have realtime operating systems, so latency and dropouts can be a problem unless you program them very carefully. And even then it's not 100% predictable what's going to screw up the signal path.
The IQBuds from https://www.nuheara.com/ have been a godsend for my daughter who has hyperacusis. The newer Boost model seems to be advancing further with diagnostics to help figure out the required sound profile of the listener.
I'm not sure I understand how hearing aids work. I think they pick up sound and amplify it for the user, giving them the ability to adjust the volume.
I remember seeing my grandmother's aids. They had a little knob on the side to adjust the volume, and if she turned one to high they would produce an ear piercing loud 'shriek' for eveyone in the room.
This was years ago, I'm sure the technology has progressed since then. But now that I really think about it, how does a device like that just not accelerate hearing loss.
We know we're not supposed to listen to earbuds/ headphones too loud, or risk ear damage. Seems like hearing aids are a kind of earbud that amplify external sound.
Seems like a high risk of folks blasting the volume, and damaging already poor hearing even further. Or a least a sure path to a nice case of tinitus over time.
The most common type of hearing loss is age related hearing loss. This type of hearing loss makes it difficult to hear high frequencies. The main thing a hearing aid does is compensate for this by adjusting the volume of high frequencies. But here's what you're missing - The key is to amplify at low volumes and reduce at high volumes, AKA dynamic range compression [2]. This allows people to hear better at low volumes but not blast their ears at high volumes.
FYI - The ear piercing shriek you heard was from poor feedback cancellation on the hearing aid. Hearing aids have a microphone and speaker so feedback is common and a nightmare.
I have a set of the modern-but-cheap NHS hearing aids.
The diagnostic process for getting them involves playing a set of random quiet tones, and you press a button whenever you hear one (and not when you don't). This produces a hearing profile showing how much hearing loss you are experiencing and at which frequencies. Usually the higher ones. If the profile is bad enough and you are given the hearing aids, the profile is downloaded into them and used as a parametric equaliser.
The amplification is not user-controllable, so you can't set it to dangerous levels.
There is also feedback cancellation - there may be a small shriek on power-on (along with the cheerful bootup chime), but it detects this and mutes that frequency.
They aren't magic, but they do make it much easier to understand speech, especially consonants and 's' sounds with high frequency components. Also little things like being able to hear my oven timer's high pitched beep when not in the kitchen.
There is a latency on the amplification and filtering. The ear adapts but I can occasionally notice it.
Battery life is about a week from non-rechargeable zinc-air batteries, £10 for 60 from Amazon or free on the NHS if you can be bothered to go to them.
- We don't really care if we further damage the hair cells that don't work.
- Outer hair cells amplify sounds. If they don't work, well, gotta amplify them some other way.
- A phenomenon called "recruitment" can cause loud sounds to be more painful for those with hearing loss. So you may not be able to amplify everything.
Hearing aids are a bit more sophisticated than an amplifier; they also act as an equalizer, compressor, feedback cancellation, and a bunch of other features of dubious benefit.
We do care and take great pains to prevent further damage to the hearing systems. All hearing aids will have a MPO (maximum power output) setting. All hearing tests (should)include a test to determine the maximum threshold of volume level.
Only in cases of sever to profound will a hearing device be programmed to exceed a safe normal hearing level.
Outer (inner actually) hair cells receive an input and there movement sends an electrical signal down the auditory nerve. In cases of hearing damage these hair cells are not as receptive and require a stronger "push" to move.
Dubious (in your opinion) or not, the other features are designed to improve the understanding of speech especially in noisy situations.
===============
Hearing aids cost a lot of money.
no question.
But they are not just devices pulled from the shelf and stuck in your ear. They require both initial settings (derived from hearing exams) and frequent follow ups as the user adjusts.
What you're missing, in short, is filtration and delivery.
Most hearing aids don't deliver sound directly to the damaged ear canal, but also utilise other sound delivery mechanisms. Like induction. This can help prevent damaging the ear internals further.
They also rarely deliver a 1:1 version of the sound in the world around us, because a damaged ear drum already distorts the sound it receives. There is no need to make it harder for the brain to filter out background noise. These filters can be simple - a dial switch on the device, or they can be complex - adaptive filtering based on the current environment. The filter complexity and effectiveness is usually reflected in the price, but as software gets better and hardware more powerful things are slowly shifting towards a better median.
The higher-end hearing aids can also be tweaked by the specialists involved to avoid frequencies that can further damage the ear, but that tends to be on a case-by-case basis and is difficult to tune correctly for an individual.
But you're right - if the hearing aid isn't tuned correctly, or the individual regularly just turns it all the way up, it can lead to further loss. Which is why many doctors have regular appointments to check the device is in a safe range.
The bad habit of the user, turning the device up, can usually be prevented by better sound filtration. They're turning it up because they can't hear something they're trying to focus on, making it easier to focus at lower volumes can curb the habit.
> Most hearing aids don't deliver sound directly to the damaged ear canal, but also utilise other sound delivery mechanisms. Like induction.
I don't think this is correct. All hearing aids do work this way, and I also don't know of any way that (electromagnetic?) induction could be used to deliver sound.
In a person with hearing loss, not all frequencies are affected equally. Hearing aids can compensate by
1. Amplifying the affected frequencies (this is by far the most common approach) or
2. Compressing and pitch shifting the sound to a range that the user has better hearing.
When I studied at Uni, some lecture halls had induction, where the sound recorded by the microphone would be transmitted via an inductive system throughout the entire room and compatible hearing aids would be able to use that sound instead of having to boost the audio from the speakers throughout the hall.
Disclaimer: Absolute layman here, but afaict they just mixed the low volume parts higher, so of course you can hear them better. Unless you can't hear those parts at all in the uncompressed version, I see no reason to worry.
Related point: There is a multi billion dollar market to someone who can make a 2 part aid which is almost invisible.
Something like a smartphone handling the initial processing and then transmitting via a small earpiece inside the ear with some innovative design for making it discreet.
There's plenty of hearing aid apps on iOS and Android. They haven't really taken off because of the delay introduced by the mobile OS and the wireless transmission (> 10ms) causing you to hear an annoying echo effect.
On the flip side to that, with {earbuds} becoming nearly ubiquitous (Samsung Buds, etc), wearing an actual hearing aid hardly makes you stand out anymore.
The novelty is the application, at the price point, tested against a specification. Given that this is an invention/design, seems like a completely respectable piece of work that is not at all redundant (which is the implication I read in your question) even if obvious in retrospect.
> The LoCHAid costs only 98 cents (<$1) to mass manufacture and can be personalized for each user through a 3D-printable case.
> It is designed to be an over-the-counter (OTC) self-serviceable solution for elderly individuals with ARHL.
> Electroacoustic measurements show that the device meets most of the targets set out by the WHO Preferred Product Profile and Consumer Technology Association for Hearing Aids.
> Simulated gain measurements show that the LoCHAid is well fitted to a range of ARHL profiles for males and females between the ages of 60-79 years.
> Overall, the measurements show that the device has the potential to benefit individuals with ARHL. Thus, our proposed design addresses a long-standing and grand challenge of affordable and accessible hearing technology for every elderly person on this planet.
There are lots of inexpensive hearing aids available on amazon right now.
They say they are personalized, but that seems to only be for physical fit.
I suspect, but do not know for certain, that they also need to be tuned to the individual sonically. This would be make things understandable instead of shrill, and prevent additional hearing loss from overamplification.
Maybe the same as getting eyeglasses that don't match your prescription.
I understand that hearing aids, as a medical device, are a bit of a racket, costing thousands. But, some new policy is in the works that favours consumer tech innovation. Anyone knowledgeable?
Yeah, the OTC (over-the-counter) hearing aid act passed in 2017 [1]. It says the FDA has to release reduced regulations for the sale of hearing aids OTC by August 2020. There will be a bunch of new players, e.g. Bose HearPhones and maybe even Apple (checkout Live Listen).
The challenge will be how to fit a hearing aid without an audiologists help. This will be especially difficult for older people.
Hopefully it will bring down the price of hearing aids substantially though.
That's actually not a bad idea, a lot of people already have headphones with integrated microphones and processors.
Noise cancellation headphones could be easily transformed into hearing aids with a change of the firmware. In fact, they could be excellent hearing aids, because they probably have more computing power than the average professional hearing aid.
The microphone amplifier is single channel, the output amplifier is stereo, though they only use one and drive both jack outputs from the right channel.
Zero innovation, and an implementation that wastes lots of power. Why would you use a volume potentiometer at the OUTPUT of the amplifier? It turns most of the output power into heat. And why would you use a stereo amplifier and short the two channels together to get a mono amplifier?
You can already buy (in ear) hearing aids for less than $3 from China. A little bit more money even gets you rechargeable ones.
Also: Even in developing countries, more and more people have smartphones. In fact it might be easier to get a smartphone there than a professional hearing aid. There are apps that act as a hearing aid, taking the sound from the microphone, amplifying and filtering it, and sending it to the headphone output. Unlike with this project, the use can individually adjust the frequency response to his hearing.