Author Topic: "Hearing Assistant/Aid"  (Read 3930 times)

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Offline jeroen74

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Re: "Hearing Assistant/Aid"
« Reply #30 on: February 12, 2013, 09:11:19 AM »
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Can a patient get used to it and start to recognize speech better? Or maybe it has side effects? Wrong glasses can cause headache and nausea, how about wrong hearing aids?

My daughter has cochlear implants (direct electrical stimulation of the auditory nerves) and this sounds highly unnatural; everyone sounds like a Cylon . This does not cause nausea or headaches. At most it can be tiresome.

Offline qno

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Re: "Hearing Assistant/Aid"
« Reply #31 on: February 13, 2013, 02:44:06 AM »
Hi all,

Some ideas:
Years back i saw some studies with multiple microphone array's that gave a directional effect.
Spacing between the mic's would attenuate specific frequencies and amplify others.

A hearing problem does not always mean the absolute sound level hearing.
One can have a good conversation in a quiet room but as soon as environment sounds at specific frequencies appear following the conversation becomes a problem.
I have anticipated in some test where a tape was played with a newsreader at a normal conversation level.
Then the same tape was played but white noise was added until the signal noise ratio was 3 dB.
Very quickly the newreaders voice was difficult to follow.

I had a friend who was a shortwave radio HAM. He could pick up HAM conversations burried in noise where I could hardly discriminate a calling station. This was training the brain to do the DSP.
I admire people who can have a conversation in a Disco or on a factory floor with heavy equipment.
Altough i think they do more lipreading than hearing.

Understand that when you amplify sound it also amplifies the unwanted surrounding noise.
The trick is to discriminate those 2 and only amplify the sound you want.
The easiest way to do this is make the distance to the sound you want to hear short and the distance to the noise large.
If you decouple the mic from the earpiece and point it to your subject you will do better that fancy DSP algorithms.

Hide your micophone in a ring or watch and you can bring it discretely to the subject.
Maybe a bluetooth earpiece with some bluetooth   microphones will get you going.

Using both ears and 2 channel audio will give a stereo image in your head. This will make it easier for the brain to conentrate on a single voice in the stereo image.


Why spend money I don't have on things I don't need to impress people I don't like?

Offline jeroen74

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Re: "Hearing Assistant/Aid"
« Reply #32 on: February 13, 2013, 02:55:26 AM »
I think no algorithm has been invented or found yet that can separate one voice from background noise like the human brain can. There's more then just simple frequency domain filtering as multiple voices occupy the same frequency band.

Offline Marco

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Re: "Hearing Assistant/Aid"
« Reply #33 on: February 13, 2013, 03:50:16 AM »
With multiple microphones you can isolate sources. ICA is a famous algorithm for this for instance, but requires as many microphones as sources I think so is not the most practical one.

Offline mswhin63

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Re: "Hearing Assistant/Aid"
« Reply #34 on: February 13, 2013, 12:00:22 PM »
I run an assistive device business in Australia and experienced in many aspect of hearing loss. The issue with any electronic device is that the product is only as good as the weakest link.

In a hearing aid the weakest link is the microphone. It is so damn small. For any of the initiated compare a large dynamic microphone with a lectern microphone on a podium. You can shove a microphone directly into your mouth and still get a good sound while the podium microphone always gets up peoples noses when they do not know how to talk into them.

Physic dictates the size of the diaphragm will naturally resonate at higher frequencies based on smaller sizes. Filtering is the only way to deal with this but the hearing aid is  such a small device that it is hard to place good filter whereas body aids are easier. This is why many people including my wife love the older larger hearing aids.

Enough said I am going back to Uni to study Electronic Engineering as I am only a lowly Technician and I have a idea that after listening to Dave may make it open source the main idea is to deal with the microphone in a way to avoid recognition and allow people to wear the device in confidence. It involves my wife and her excellent crafting capability as well. It maybe so simple that I may just use it to gain my experience in Science and engineering and give it away.

For a minor plug not my website but my suppliers website these products from Bellman are the best I have provided in a long time. There are so many other alternatives around but performance is not as good. Unfortunately market power dictate these to be quite costly. www.bellman.se/audio
Half a century later and I finally studying.

Offline NiHaoMike

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Re: "Hearing Assistant/Aid"
« Reply #35 on: February 15, 2013, 05:10:33 AM »
Apart from the obvious voice band filtering, you could use directional microphones aimed to give the highest sensitivity at typical conversation distances.
Electrical engineering would be a lot more fun if I looked like Tiffany Yep. As if it's not fun enough already...

In power electronics, transistors should ideally be either fully on or fully off, because a half-on transistor just makes a really poor imitation of Tiffany Yep...

Offline mswhin63

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Re: "Hearing Assistant/Aid"
« Reply #36 on: February 15, 2013, 08:50:06 PM »
Apart from the obvious voice band filtering, you could use directional microphones aimed to give the highest sensitivity at typical conversation distances.

There are already hearing aids available with voice band filters and up to 6 microphones in some instances but way out of the price range of most people with hearing loss. Some of my former clients purchased $6 - 10,000 per hearing aid to achieve this and what concerns me about the practicality is why did they come and see me in the first place.
Half a century later and I finally studying.

Offline NiHaoMike

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Re: "Hearing Assistant/Aid"
« Reply #37 on: February 16, 2013, 05:29:15 PM »
How difficult is it to create a cheap open source version? Fast ARM boards like the Raspberry Pi are quite cheap nowadays.
Electrical engineering would be a lot more fun if I looked like Tiffany Yep. As if it's not fun enough already...

In power electronics, transistors should ideally be either fully on or fully off, because a half-on transistor just makes a really poor imitation of Tiffany Yep...

Offline Marco

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Re: "Hearing Assistant/Aid"
« Reply #38 on: February 16, 2013, 10:54:54 PM »
Most of the cost is in the non recurring part ... ie. find someone mad enough to actually do it and not charge for his time.

Also if you try to use advanced signal processing with multiple microphones for voice isolation or frequency compression I expect a contributory infringement lawsuit, so better not publish under your real name.

Offline jeroen74

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Re: "Hearing Assistant/Aid"
« Reply #39 on: February 17, 2013, 12:30:26 AM »
As a practical note.... my daughter goes to a regular school and to help her hear the teacher better, the teacher wears a wireless microphone. My girl wears a receiver that retransmits the received signal to the hearing aids via a standard inductive ring? interface.

So even with four DSP cores they can't even begin to come close to the processing capabilities of the human brain, which after all, just has two microphones as input ;)

IIRC these hearing aids already have two microphones to help voice separation, one omnidirectional one and a unidirectional one. The algorithms is what sets the four different manufacturers apart, but they all function about just as good. It's subject of major marketing blahblah.


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