Sound Sensors

I've been looking at using microphones to detect sound and measure the intensity of the pitch of speech in a room which would then be converted to abstract graphics on a surface. Another idea would be to pinpoint where people are in the room by the noise they make which would be captured in the graphics created. Therefore the graphics would be constantly evolving in relation to what is happening in the room. All I need to do is find out how to do this!! I think I need to convert the air pressure signals to electrical signals to do this?!?