Electronics > Open Source Hardware

"Hearing Assistant/Aid"

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Hey everyone,

Well after reading the OSHW Priority List I was reminded that one of the reasons people don't get proper healthcare is because they can't afford it. And what's one thing that is grossly overpriced: Hearing aids.

Now...Modern hearing aids are actually pretty complex little devices. The top of the range ones are definitely pretty cool. Good example of electronics miniaturization...However, I think there is still a lot of people out there that would much rather have their hearing back then care about whether the device fit's in their ear. Could be wrong..

I've seen them on Amazon, but all of them have some sort of problem..They are called "hearing assistants". They cost anywhere from $20-200. In fact, my grandpa had one. It was a real peace of garbage though. Wouldn't it be nice if there was a very solid solution that offered very respectable performance for a very modest price. I would not plan on making it something that would fit on your ear, rather a device that would fit in your pocket and use a standard earbuds/phones for sound.


Of course, this could be nothing but a fleeting thought, but I thought I would put it out there. Here would be some goals

Small form factor (fit into a pocket)
Customization (3 band active equalizer)
Long battery life (TBD)
High quality sound (no static/noise/distortion)
Simplicity (make it easy to use for the intended audience (65+))

Of course those are pretty basic goals, but important ones..

As far as the circuit goes...

Electret mic --> Mic Preamp --> 3-Band equalizer --> Headphone amplifier --> Headphones

Unsure of how batteries and power would work. Rechargeable would add some issues possible.

The whole thing would probably just be a ton of op-amps. Simple and effective.

Any ideas?

Straightforward to understand, perhaps, but not necessarily that effective, and certainly not small.

I'd use a chip more like this:

This device integrates a stereo codec, programmable gain, equaliser, dynamic range compression and headphone amplifier, all into a device 4mm square. Add a simple microcontroller such as a PIC to program it up at power-on, and maybe provide a few different settings for different environments. The whole thing would be the size of a thumbnail and would operate off 1.8V for ages.

Very interesting. It seems awfully complex for such a simple operation of mic -> earphone amplification.

Half way through the datasheet. Phew. Hell of a chip. My serial communication skills pretty much suck.

Is there any similar type of device that does not have so many features? Say 1 mic input, 1 output, volume control, and equalizer? Anything like that available?

I've been looking at the TI OPA332 op amp family. http://www.ti.com/lit/ds/symlink/opa4322.pdf

I don't know. Looking around.

Short Circuit:
AD, DSP, EQ, DA, 1.3V

Thanks. Just out of curiosity...

Does anyone know how to choose a proper telecoil/T-Coil?.. you know the things that are in hearing aids that pick up magnetic  field and translate it into sound (has to be from a telecoil transmitter, or from your phone)

I'm looking around at different telecoil manufacturers. Some have inductances of 50uH, some have 100mH, or bigger or less. Varying sensitivities etc.

Any idea how to choose one?


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