Using it is simple:
connect GND to ground, VCC to 2.4-5VDC.
For the best performance, use the "quietest" supply available (on an Arduino, this would be the 3.3V supply). The audio waveform will come out of the OUT pin. The output will have a DC bias of VCC/2 so when its perfectly quiet, the voltage will be a steady VCC/2 volts (it is DC coupled). If the audio equipment youre using requires AC coupled audio, place a 100uF capacitor between the output pin and the input of your device. If youre connecting to an audio amplifier that has differential inputs or includes decoupling capacitors, the 100uF cap is not required.
The output pin is not designed to drive speakers or anything but the smallest in-ear headphones - youll need an audio amplifier (such as 3.7W stereo amp) if you want to connect the amp directly to speakers. If youre connecting to a microcontroller pin, you dont need an amplifier or decoupling capacitor - connect the OUT pin directly to the microcontroller ADC pin.
For audio-reactive projects, we suggest using an FFT driver library which can take the audio input and translate it into frequencies.