Open source hearing aid algorithm

Hello. I’d like to draw the attention of the community to the BioAid research project. We have developed a novel sound-processing algorithm for hearing aids based on our knowledge of the signal processing that occurs in the human auditory system.

BioAid: The Biologically Inspired Hearing Aid

To get the algorithm out of the laboratory and reach a larger audience, we recently released an implementation of the algorithm in the form of an iOS app. This will turn any recent iOS device into a basic hearing aid. The app is completely free, has no restricted functionality, and contains no advertising. This is a completely non-profit exercise. The algorithm source code is also freely available for the curious.

Due to limitations with the hardware, it is certainly not going to replace modern high-end commercially available hearing aids. However, we hope that the device will benefit some people in certain situations. This is a research tool, so we’d love to hear any feedback, positive or otherwise.

I hate hearing feedback. Oh not that kind of feed back

I'm leery, how "knowledgeable" could Apple possibly be about the signal processing that occurs in the human auditory system?? They make comps, tablets and mp3 players, sure they're electronics but they're worlds apart from hearing aids.

This might be good for older people that have mild hearing loss but don't want to get aids because it would mean....well they're old. I haven't tried it, but I don't need to. I can tell you right now this wouldn't do diddly for me, or most of the people here probably. Most of us have hearing loss that is waaaayyyyy beyond what an app on a phone could help with.

nrclark said:

Hello. I’d like to draw the attention of the community to the BioAid research project. We have developed a novel sound-processing algorithm for hearing aids based on our knowledge of the signal processing that occurs in the human auditory system.

BioAid — The Biologically Inspired Hearing Aid

To get the algorithm out of the laboratory and reach a larger audience, we recently released an implementation of the algorithm in the form of an iOS app. This will turn any recent iOS device into a basic hearing aid. The app is completely free, has no restricted functionality, and contains no advertising. This is a completely non-profit exercise. The algorithm source code is also freely available for the curious.

Due to limitations with the hardware, it is certainly not going to replace modern high-end commercially available hearing aids. However, we hope that the device will benefit some people in certain situations. This is a research tool, so we’d love to hear any feedback, positive or otherwise.

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I will look into this. Perhaps it can tell whether you need a frequency adjustment. Might replace an audiologist, but I'm unsure about an aid.

So basically, it turns your expensive smartphone into the equivalent of a really cheap body worn hearing aid??

Bottesini said:

So basically, it turns your expensive smartphone into the equivalent of a really cheap body worn hearing aid??

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That's what it sounded like to me, but I didn't follow the link within the link to find out more. It sounded like you hook head phones up to the iphone, and sound that would normally go into the mic when you made a phone call would be amplified over the headphones?? And how do you use your phone? What if you want to text someone? Or play a game, my phone is my phone not my hearing aid. I'd like to use both at the same time!

Great suff!! I'm glad this a gotten a little interest. Allow me to respond to some of the comments.

I hate hearing feedback. Oh not that kind of feed back

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This made me laugh. I should definitely avoid that word when discussing hearing aid technology on the web!

I'm leery, how "knowledgeable" could Apple possibly be about the signal processing that occurs in the human auditory system...

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Sorry for any confusion here. I developed this application as part of a team of hearing researchers based in a university department (see the contacts page on the website for more information). The software is released on an Apple device, but it is not an Apple product. Our team has a lot of experience in the fields of psychoacoustics and modelling processes that occur in the human auditory periphery.

Might replace an audiologist, but I'm unsure about an aid.

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We are certainly not trying to replace anybody! Lots of people now carry a powerful multi-purpose computer around with them (in the form of a smartphone or music player). It is very attractive for the hearing researcher to test ideas on a mobile platform, as a research device can be made freely available to a huge international audience. It is a much faster way for us to get an idea out of the lab, when compared to developing a wearable hearing aid prototype. However, a hearing aid built as a phone app will certainly have limitations compared to a dedicated device due to hardware limitations with the hardware and fitting procedure. Part of the project is to asses what the biggest limitations are.

So basically, it turns your expensive smartphone into the equivalent of a really cheap body worn hearing aid??

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Well, yes and no. The processing occurs on a mobile device, so this has to be carried around. It is certainly less portable than a modern dedicated hearing aid. This is one of the limitations of such a device, and this is why we stress it may only be useful in certain situations. However, it might turn out to be a real asset in some situations. We are hoping to find out what those situations may be via communication with users.

The processing that occurs in the application is rather sophisticated (not like some cheap body worn aid). This is not a simple gain application like some of the others available on the app store. BioAid is a multiple-band dynamics processor. The App splits the incoming signal into multiple frequency bands and then regulates the dynamics of the signal independently within each band before recombining the signal and presenting it to the listener. Interestingly, BioAid does this in a way that faithfully mimics what we know cochlear processing. This is a departure form the adaptive gain control techniques used in current digital hearing aids. Whether or not this novel processing strategy has benefits over standard techniques employed in current hearing aids is a research question. The free app is just one avenue of exploration. I am certainly not making any claims about performance.

It sounded like you hook head phones up to the iphone, and sound that would normally go into the mic when you made a phone call would be amplified over the headphones?? And how do you use your phone? What if you want to text someone? Or play a game, my phone is my phone not my hearing aid. I'd like to use both at the same time!

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Apologies again for my rather cryptic original message. The app runs in the background, continuously processing sound from the microphone and delivering it over headphones. If the phone rings, or you want to listen to music, the BioAid app will be disabled and your device will work as a normal phone. The hearing aid will continue to operate in the background when playing games. If you load up a game, you will still hear ambient sounds in your environment being processed by the aid. At the same time, the sound effects from the game will be mixed with the hearing aid signal. The app will not render your phone unusable for its primary purposes.

BioAid is not going to replace a dedicated hearing aid for all-day use, but we hope that some use cases will be revealed where some people find it really useful (perhaps more so than their current hearing aid). Releasing the BioAid algorithm in the form of a free app should help us identify these situations, which will in turn allow us to make better decisions about the direction of future research.

Don't hesitate to quiz me if you want more information or have more questions!

ambrosia said:

I'm leery, how "knowledgeable" could Apple possibly be about the signal processing that occurs in the human auditory system?? They make comps, tablets and mp3 players, sure they're electronics but they're worlds apart from hearing aids.

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Anyone can be an apple developer and make an iPhone app. This app is not directly from Apple.

I tried it out ...couldn't hear much except myself sniffling lol got my friend to try it who's hearing and she said it amplified a good amount but then again she's hearing sooooo lol but I guess it can be a good app for milder hearing losses. I guess it's a good alternative to see if you want hearing aids? like sort of a trial run ?

For the developers...the app is very confusing. For people who have no background on what the software and the settings mean you need to make it more user friendly or else people are not going to A. Use the app properly or B. find it too confusing and not use the app at all.

I know a good amount about hearing loss and most technical terms and I had NO idea what to do ..I just pressed buttons...so again you may want to make it more user friendly

I just tried it out with both headphones (without my hearing aids) and using direct audio input with my hearing aids.
With headphones....even with the most amplification I couldn't hear anything. I tried every "program" of your app.
With my hearing aids and direct audio input (which is already amplified to match my profound hearing loss) I did notice a difference between the settings...some settings eliminated all the useful sounds (like speech) and amplified the sounds I don't normally hear (hissing sounds). Other settings amplified the mid frequencies and cut out highs and lows.
Maybe this would be helpful for people with ridiculously mild hearing loss but for me it did about the same as an analogue body aid circa 1980 would do minus the volume. (but I wasn't alive in 1980 so I can't be sure).

But I don't want to seem like a complete jerk. I'm sure the app could be useful for some people but a majority of the people here have at least moderate hearing loss and many, such as myself, have severe to profound hearing loss. I also have experience in hearing science (but more on the biological side) and I'm willing to discuss the intricacies of hearing, psychoacoustics, and cochlear mechanics with you.
What the previous commenter posted about user friendliness is very true.
I can explain my audiogram and my hearing loss in more detail than my audiologists. I find myself explaining to them every time that increasing amplification of high frequencies doesn't help me, it actually impedes my speech understanding.
However, navigating your app is difficult at best. I went through every setting and read the info for each but had a hard time deciding which would help me most.


But your app may be good for baby boomers. Just keep in mind that most users of your app won't have decades of experience with hearing loss and likely won't know what an audiogram is, much less know whether they need high or low frequency amplification.

Perhaps you could add some simple "do you have a hard time understanding women and children" or "are men with deep voices more difficult to hear" questions as a way to translate the technical side to everyday life.

First off, many thanks for trying it out and responding. Let me address a couple of the comments

I tried it out ...couldn't hear much except myself sniffling lol

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There could be a couple of explanations for this. First one that comes to mind is if the hardware volume on the device is too low. We recommend people don't try the aid with maximum volume to begin with, in case the output is uncomfortably loud. However, once the device is running the volume buttons on the side can be adjusted to boost or reduce the level as necessary. The second thing that might make the experience sub optimum is using headphones with a microphone built into the chord (like the ones supplied as standard). These microphones are designed to pick up the sounds made by the phone user, not to pick up sounds in the user's environment.

You might have luck experimenting with different headphones. If headphones are used without a built in microphone, the app will default to using the mic in the iOS device. This might give a better experience. Also, different headphones have different sensitivity, meaning some headphones will sound louder at a given volume setting than others.

navigating your app is difficult at besty

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Noted. Thanks. This will need some serious thought. The app is already quite wordy with all the various information boxes, as I'm sure you've noticed. Perhaps some built in testing would get the listener to a good starting point from which they could try different settings?

With my hearing aids and direct audio input (which is already amplified to match my profound hearing loss)

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I would not recommend daisy-chaining the BioAid output into another hearing aid processor. This is unlikely to result in a satisfying experience as the processors are not designed to work together harmoniously. However, many thanks for trying it out and reporting your experience.

This is all really useful and I'm very grateful for the responses!

nrclark said:

First off, many thanks for trying it out and responding. Let me address a couple of the comments



There could be a couple of explanations for this. First one that comes to mind is if the hardware volume on the device is too low. We recommend people don't try the aid with maximum volume to begin with, in case the output is uncomfortably loud. However, once the device is running the volume buttons on the side can be adjusted to boost or reduce the level as necessary. The second thing that might make the experience sub optimum is using headphones with a microphone built into the chord (like the ones supplied as standard). These microphones are designed to pick up the sounds made by the phone user, not to pick up sounds in the user's environment.

You might have luck experimenting with different headphones. If headphones are used without a built in microphone, the app will default to using the mic in the iOS device. This might give a better experience. Also, different headphones have different sensitivity, meaning some headphones will sound louder at a given volume setting than others.



Noted. Thanks. This will need some serious thought. The app is already quite wordy with all the various information boxes, as I'm sure you've noticed. Perhaps some built in testing would get the listener to a good starting point from which they could try different settings?



I would not recommend daisy-chaining the BioAid output into another hearing aid processor. This is unlikely to result in a satisfying experience as the processors are not designed to work together harmoniously. However, many thanks for trying it out and reporting your experience.

This is all really useful and I'm very grateful for the responses!

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for us severe to profound users the only to try the app is through a streamer since we can't use regular headphones without hearing aids. I would have tried over the ear headphones to try it out if I had a pair but I don't. But the navigation of the app definitely needs to be addressed first I think so that more people may wanna try the app without being overwhelmed by just looking at it :p lol

lovezebras said:

for us severe to profound users the only to try the app is through a streamer since we can't use regular headphones without hearing aids. I would have tried over the ear headphones to try it out if I had a pair but I don't. But the navigation of the app definitely needs to be addressed first I think so that more people may wanna try the app without being overwhelmed by just looking at it :p lol

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Zebras is right.
I wasn't "daisy chaining" your program with my hearing aids in the way an engineer would think.
I was simply using my hearing aids to get enough volume so that I could tell a difference between your programs.

It might be helpful/it would be awesome if every hearing person were forced to be deaf for a day...
If you want to get a sense of what hearing loss sounds like, go buy some good ear plugs and find or borrow some industrial ear protectors.
That combination will give you a glimpse of what 40db (mild to moderate) conductive hearing loss sounds like.
Keep in mind that people like me have hearing that starts at 90dB (and keep in mind that decibels are logarithmic).

For sensriouneural hearing loss, you have to add in a loss of frequency resolution (for example, I can't tell the difference between two or even four piano notes) and distortion (high pitches sound like static to me).

Severe to profound hearing loss doesn't mean the absence of sound, just the a sense of sound that would be helpful. I can sometimes tell that there is a sound but it makes no sense.
I can't tell where the sound is coming from, what it is, or what it means.

Why target iOS?

Since iOS and Android have won the smartphone sweepstakes, iPhones are too valuable to use as dedicated hearing aid stand-ins. Folks want to use them as phones and to run various other apps.

What about other operating systems that are basically roadkill on the information autobahn? On eBay you can buy a Windows Mobile 5 or 6 smartphone for about five bucks. Either use that O/S or perhaps reflash with a purpose-driven Linux clone or something. Underneath variations in all the different operating systems there is a lot of hardware consistency; mainly ARM CPUs with 32MB up to 1GB or more of RAM, plus a substantial amount of flash memory. Most have headset jacks: one channel in/two out. Suboptimal for losing stereo clues but still able to deal with inter-ear differences on the output side.

Replace weak batteries, throw in a charger and a made-in-China headset, and total hardware cost is still only $10-15. There must be hundreds million people on the planet unable to afford "real" hearing aids who could benefit.