This module features the MSGEQ7 graphic equalizer display filter. It will give your arduino ears. Sound is broken down into seven frequency bands and the peak level for each band can be read. The seven frequencies measured are as follows: 63Hz, 160Hz, 400Hz, 1kHz, 2.5kHz, 6.25kHz and 16kHz..
The Spectrum Shield enables your Arduino with the capability of splitting a stereo audio input into 7-bands per channel. You can then read the amplitude of each channel using the ADC on your Arduino allowing you to control everything from LEDs to motors, pumps to relays, or even fire, all with sound..