With less than $5 and it is incredibly simple. I had known about the technology, but thought it involved a more sensitive and expensive equipment. It turns out you can make yourself a simple Laser Microsphone with a $2 laser and the light sensor from a nightlight...

The technology involves around the fact that sounds [of your voice] are simply waves that cause vibrations in the air. The windows in any room will vibrate accordingly when impacted with these vibrations. If you point a laser light at the window and capture the reflected light on a sensor, any vibration on the window will be reflected and captured in your sensor. It is just a matter of translating the vibrations back to sound with software and any laptop with Windows will do that for you.

Read more: [via LifeHacker] http://lifehacker.com/...