Copyright 2015 Richard W.E. Furse
Chordal is a single-function app which uses a microphone to listen to sounds and shows 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 a keyboard tuned at 440Hz. It covers notes (or harmonics) from C2 (65Hz) to B7 (3951Hz) in octave bands.
Or, putting this another way, the keyboard lights up where there's pitch. Watch your sopranos spread the note and flatten. Works with a wide range of instruments.
Inspired by a conversation with Chuck Knowledge.