Roll
Visual representation of any audio chroma content
Drag the screen graph to change the roll speed.

This app shows the chroma content of the incoming signal. It means is analyzes the frequency spectrum and sums them according to one of the 12 pitch classes. The relative power of every pitch class is plotted, showing the primary tones of the audio signal. Pure sine tone will give us one line filled and noise will make all the bands glow equally bright.