What is TTM?

Turntablist Transcription Methodology (TTM) is a notation system for scratching and turntablism designed by John Carluccio, Ethan Imboden and by Raymond Pirtle (DJ Raedawn). It is intended to be an intuitive graphical representation of the movement of a record whilst performing with a turntable [...]
– Wikipedia

Probably best to understand with an example video: Rob Swift - TTM demo (youtube)

Etch a Skratch

etch-a-skratch.wbcrew.de Live Demo

The scratch is "designed" with coordinates, which are displayed in the graph. The skratch sample mp3 file will be played according to the graph, which means it needs to be chopped, reversed and the speed needs to be aligned for each single segment via Web Audio API. The audio-buffer-utils library is great for doing this!

All patterns can be phased, flipped or adjusted in speed (double/half time).

Additional, there's a SVG animation of a turntable and mixer with crossfader, which is synchronized with the skratch pattern. This way beginners can get a demonstration of a skratch in slow motion and can try to learn the movement routine from it.