The SparkFun Sound Detector is a small and very easy-to-use audio sensing board with three different outputs. The Sound Detector not only provides an audio output, but also a binary indication of the presence of sound and an analog representation of its amplitude. The three outputs are simultaneous and independent, so you can use as many or as few as you want at once.
Resources
Schematic
Eagle Files
Hookup Guide
Datasheet(LMV324)
GitHub