Is there any device which converts vibrations or noise into electricity?

I would like to know if there is any device which converts vibrations from human voice into electricity. It will be a better way of producing electricity at a free cost.

A Piezoelectric Transducer‎ is one device that does that.... A good example of a device that utilizes a Piezoelectric Transducer‎ is a microphone. It is indeed a good option for generating electricity and a very good way to promote renewable energy however such only generates very low electricity... more like just enough to charge devices such as Cellular Phones. Try to do more research and look for other ways to harvest Electricity from noise/vibration, there might be other ways to do it.

Linear Technology makes "energy harvesting" devices such as the LTC3588-1.

http://www.linear.com/product/LTC3588-1