Sonic Visualiser 1.0 showing a waveform pane and a melodic range spectrogram pane. (The music is “After the Pain” by Carlos Pino.)

Overlaid on the spectrogram is a note layer, showing the output of a note-tracker Vamp plugin that is being evaluated. The notes from the tracker are played using a piano sample, configured in the plugin dialog visible.

via Sonic Visualiser.