Perhaps you’ve heard the terms “low-pass,” “high-pass,” or “band-pass,” and like me realized it had something to do with the frequency fed to speakers, but never gave it much more thought. Check out the video below to see what these terms mean in practical terms:
As it just so happens, the device used in this excellent illustration is running on an Arduino board. In combination with the Audio Hacker Shield, an Arduino can be set up to do fun audio experiments like filter certain frequencies as shown here, as well as record and modify the playback speed of an audio source. It can also be used as a voice changer, MIDI device, a drum machine, and many other experiments depending how it’s set up.
A DJ Shield Deluxe, shown covering the Arduino and Hacker Shield, provides the fun knobs and buttons. As interesting as that looks modifying audio, it should be noted that this device can also be used as any other sort of Arduino input.
So if you want to start hacking audio with your Arduino, or simply illustrate different filtering techniques, this shield looks like a great place to start. You can find even more info on nootropic’s site.