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There are a lot of ideas on here about harvesting tiny
of spare energy with the snag of the energy not being
enough to achieve very much. I don't consider this idea
fall into that category.
Psychoacoustic compression filters out most audio data
without intrusive compression artifacts.
Most of these
probably irrelevant to the energy question, but not all.
a start, there must be a lot of ultrasonic and infrasonic
sound which currently serves no purpose at all but could
detected by a microphone, and the likes of a quiet noise
just before a louder one or masked by a louder one can
safely be removed from a recording without listeners
noticing. Moreover, noises at night, such as traffic,
ticking alarm clocks, snoring, central heating boilers and
fridges turning on and off and so forth, are if anything a
nuisance to people with good hearing. For a hearing aid,
sitting unused by the bedside, they are also wasted
Therefore, why not use the energy of these sounds to
recharge the hearing aid? Store them in a capacitor,
maybe, and release that into the battery when it runs
No more need to change batteries as often.
Oh, and the reason why i think it's more practical for this
device than others is that a hearing aid needn't use
Hearing aid power consumption
"1-10 mW" [csea, Oct 28 2011]
Sound power vs SPL [csea, Oct 28 2011]
No mention of using sound or not. [2 fries shy of a happy meal, Oct 28 2011]
||Hmm, let's look at a few back-of-the envelope numbers.
||From a chip manufacturer, we see that hearing aids typically consume 1-10 mW of power. [link1]
And the sound power of various sources seems also in that range (including "vivid children!"). [link2]
||The difficulty lies in the dispersal of that power over volumetric distance and the surface area of a collector used to capture the power. At 1 meter distance from "vivid children," the 1mW of power is distributed over 4(pi)R^2 meters, or about 12 square meters. If we hope to capture energy with a small diaphragm, say a 1 cm square, the most we could hope for is 1/1200 of a mW, or 833nW (nanowatts.) Rounding up to a microwatt, we're still shy by a factor of 1000 to 10,000.
||The clear answer is 5000 vivid children slaves driven to louder wailing by whips, so you can just turn the hearing aid off altogether.
||I did have a thought about including an ear trumpet.
Then you could throw away the hearing aid
||How about a tiny dynamo rigged to a self-winding watch
||How about one of those kinetic battery chargers?
It would need to be quite small, and would need
quite vigorous head movements. But it would be
a self solving problem - if the batteries go flat,
the wearer will forever be turning their head to
point an ear at the speaker, thereby assisting the
||Alternatively, a special recharging platform could
be sold with the hearing aid, on which the
behearingaided person would stand and be shaken
until the batteries were charged.
||//I did have a thought about including an ear
trumpet. Then you could throw away the hearing
||Ear trumpets are bulky and ugly, but I have a
solution for a sob-population of hearing-aid
wearers, namely those unfortunate souls who
have also lost an eye. Given that the eye socket
is now vacant real-estate in the head, an integral
ear-trumpet could be fashioned. I suspect that
the surgery needed to bring the distal end of the
trumpet into close proximity with the inner ear
would be relatively trivial.