# Can we obtain electrical energy from sound signals?

1. Feb 2, 2010

### imnitsy

can we obtain electrical energy from sound signals??

hello everyone..

i want to know that is there ny method or any apparatus to convert the sound signals into electrical energy efficiently such that it will glow a led or can acticate a buzzer!!!

well i know about sound detector circuits that detects sounds with the help of the condenser mic but the source of electric energy in them is the power supplied to the amplifier circuit..

what i want to know is that can we convert the sound signals like our voice to some remarkable amount of electrical energy ??

regards
imnitsy

2. Feb 2, 2010

### taylaron

Re: can we obtain electrical energy from sound signals??

Interesting concept, but unfortunately this experiment has been reproduced regularly by amatures. I suggest searching for videos on youtube

The following video is rather pitiful, because his method of applying energy to the piezoelectric speaker was by his hands and needless to say, more kinetic energy is transferred by pushing something than by letting typical sound waves harmlessly bumping against it.
http://www.youtube.com/watch?v=s3Ftl6n9Oq0"
To make electricity, the piezoelectric speaker must vibrate. Additionally, sound waves do indeed have kinetic energy but one would have to have a heck of a speaker to generate the sound waves required to register any useful current from the piezoelectric speaker. Let me remind you that you wanted to use someone's voice opposed to the largest loud speaker in the world.
Also, the voltage applied to a piezoelectric speaker is very high compared to the current that is being applied. You need voltage and current to make a viable power source.
Remember, using a speaker to generate sound waves and then using a series of piezoelectric speakers to recapture that energy is only making a ridiculous amount of noise and waisting electricity. It would be more efficient to hook the power to the speaker directly to a long series of LEDs.
There simply isn't enough energy in the typical sound wave to generate "some remarkable amount of electrical energy" but perhaps enough energy could be generated to run nano-electronic devices where the power needed is much much lower.

Your idea is novel, keep thinking!
Remember, one learns more from their failures than from their successes.

Regards,
-Tay

Last edited by a moderator: Apr 24, 2017
3. Feb 3, 2010

### imnitsy

Re: can we obtain electrical energy from sound signals??

well i have one more doubt about it..
what happen if we provide the peizoelectric speaker with high frequency noise signals ?

as in our surrounding we have a lot of disturbances caused by various types of noise!!!!

is there any way of utilising these noise signals to produce electrical energy without using any external power source ??

4. Feb 3, 2010

### cjameshuff

Re: can we obtain electrical energy from sound signals??

You hear lots of noise, but your ears are very sensitive sound sensors. There just isn't much sound energy around for a reasonably sized collector to harvest. Notice that the output of a microphone usually has to be amplified, the weak signal being used to generate a more powerful signal using electrical power from another source, before it's of any use.

Think of a 100 watt light bulb. Right next to the bulb, it's bright and hot, you can trap a good portion of that 100 watts with your hand. Across the room, you're lucky if you can operate a small calculator. Sound waves spread out too, and there are very few sound sources comparable in emitted power to the visible and infrared light emitted by that light bulb.

I have seen vibration energy scavenging used to power small wireless sensors, but this was in the context of high-vibration machine environments, and for that sort of application you can get by with less than a milliwatt of average power, storing up energy and releasing it in bursts if necessary. There's also things like self-winding watches that use the motion of the wearer as their power source. You're not going to get much more than that...even flashing an LED or sounding a buzzer will take very high efficiency circuitry and a considerable period of storing up enough energy first. Look up "energy harvesting", and "solar engine" for something similar using small solar cells.

5. Feb 3, 2010

### sophiecentaur

Re: can we obtain electrical energy from sound signals??

This link includes some ideas.
https://www.physicsforums.com/showthread.php?t=338283
The bottom line is that, even in sound levels corresponding to the threshold of pain, you couldn't knock the skin off a rice pudding with the power you could harvest. Your ears are very very sensitive and give you the impression that there are vast amounts of acoustic power around. In fact, there aren't.

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