This simple example project is the same as the 12-bit Sampler, but the audio sample is played in reverse. In the Arduino menu, choose File->Examples->Audio Hacker->SamplerReverse. Record your audio sample with button S1 on the Audio Hacker (top button), and play it back in reverse using the S2 button. Just as with the 12-bit Sampler, you can connect a potentiometer to A0 to adjust the playback speed. If you are unsure how to wire the potentiometer, see analog input tutorial. To enable this feature, make a minor code change to set adjustablePlaybackSpeed = true;. Arduino will prompt you to save your changed sketch to another location.