Matthew Shieh created this very interesting audio meter. Instead of the typical LM3915 VU meter, Matt  designed the amplifier to capture ambient sound from a small mic. For the interface he used a photoresistor and capacitive touch button controlled by a PIC16F716 . The photoresistor lets him dim the LEDs when it’s dark to save power. His project really shines in the write up and best of all fits into a petridish.

read