I have a question

Ok, so i was revising for my physics exam on monday and i was just learning the whole theory of how a microphone works (with soundwaves making a diaphragm vibrate which then moves a coil through some magnetic field lines inducing an analogue current). And i came up with an idea. If sound can induce current the same way that steam can by turning magnet in a coil of wire, then why can't we use sound to make electricity?

You could put some kind of a giant super-sensitive microphone in a noisy city which could generate electicity with no fuel needed! Or everyone could have one in their house or in clubs or generally noisy areas?

I am pretty sure that there is a good reason nobody has ever thought of this, most probably because it wouldn't work for some reason or other. But the idea just came to my head and i was wondering if someone would like to explain to me why it wouldnt work or if i have come up with an engenious idea which will save the world from its fuel problems (which i doubt)

Well...

The problem is exactly within the construction of microphone.

Putting it simply, such "sound powerplant" would produce jumbled electricity current, matching the noise.

Which is not really usable, as all devices are designed to use current of specific amplitude and modulation.

Damn, there i was thinking i'd saved the world!

Hm. Why not have a very stable speaker in a room designed for this purpose, pointed at an array of very stable mics? How much power would a sound plant, or rather an individual microphone, generate, soffee? More than the power paid to make the speaker in this scenario work?

Digs, speaker is NOT a good source.

For sound powerstation, you`d need monotone hum. And that is generally created expending more energy then microphones would generate.

but you know, excluding the thought of microphones, Sound turning into energy could be a good thing if you could create a device suited to doing the job.

It would be nice, as it would make cities quieter, but have you seen the sort of current generated by a microphone? it is bugger all. That is why the signal has to be passed through an amp before being useful.

Perhaps someone could invent some sort of a sound filter that only let in a sound wave of a specific frequency. No idea how that would work, but it could be doable i guess? Anyway, just a thought.

It is doable.

Problem is, that the filtering alone will consume more energy, then microphone can produce.

Stupid law of conservation.