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Record audio through vibration


#1

Hi,

I’m exploring the possibilities of recording audio in certain environments via the vibration in a solid object. My electronics skills and scientific knowledge are very rusty from spending nearly 15 years away from it so I know there are probably holes in my theory/understanding :).

Anyway, think of underwater applications or special signal detection in environments where you cannot have an exposed electrical circuit (as in, microphone). I’ve been looking at some piezo electric components as vibration sensors as well as some single axis accelerometer chips you get these days. My theory is that, assuming I find a sensor with a high enough sensitivity/frequency and mount it at the right angle to a physical surface (e.g. wood, plastic), I should be able to record audio vibrating through it.

So, what are the holes in my theory and where do I have it wrong? What should I be looking out for? What sensor would do the job (assuming I’m only interested in audio signals up to 8kHz)?

I do understand that the sound would not sound like the original traveling through air picked up by a standard microphone (or is this a wrong assumption?).

Thanks!

P.S. I’m separately exploring how a FEZ Cobra can be used to do analog to digital conversion up to 8kHz … any ideas or pointers? Seems I might have to use RLP with a task or interrupt.


#2

I know the feds use lasers to read vibration off windows to “hear” inside buildings.


#3

What is your audio source?
It is hard to detect the vibration of a solid object if the excitation is a audio.
if the power of audio source is large may you can detect the vibration.
You can use a piezo to detect this vibration but I think it is not a easy task.
What you want to do is like a measurement of ambient vibration.
Some ambient vibration sensors are very experience up to $5000.
My PhD research is related to measurement of vibration. Your topic seems interesting, maybe we can discuss more about it.
thanks