I am looking for a sound-sensitive switch - one that would increase the output according to the volume. Basically, what I want to do is string a series of nine LEDs in sequence, connected to some sort of sound-activated switch, so that they will react to the volume. For instance, a very quiet noise would only light the first one or two, music playing would keep the lights "jumping" and a very loud boom would light them all up, for a second.
I figure I can string them all to the switch in series, with varying resistors in front of them to regulate the current that gets to them. Correct?
It has been about ten years at least since I've taken any sort of electronics class.
Thanks in advance.