I need a few sound sensors that are relatively cheap (under $20 each preferred) that have a capture range of about 5 - 10 feet. It should essentially be just like this product
http://www.emartee.com/product/42148/Mini%20Sound%20Sensor
The only catch is I don't see any info about its strength of capturing sound. I will be placing the sensors at the corners of a room 10x10 (ft) and they need to work for the entire space. Thanks for your help