This single-function app uses the microphone to listen to sounds and show their overall frequency content. It is intended as a musical tool for visualisation of pitches, harmonics and harmony.
Technically, this is a conventional FFT (Fast Fourier Transform) shown as colours. These are presented over the black and white keys of a keyboard tuned at 440Hz. It covers notes (or harmonics) from C2 (65Hz) to B7 (3951Hz) using octave bands.
Or, putting this another way, the keyboard lights up where theres pitch. Watch your sopranos spread the note and flatten. Works with a wide range of instruments.
Inspired by a conversation with Chuck Knowledge.