The aim of auch (audio-checker) is to visualize music. It takes audio from the microphone and uses it to simulate an elastic and vibrating surface (chladni-tranform) or the reflection of such a surface (makyoh-transform). Many more transforms can be activated by unlocking the interactive shell.
Transcribe! is an assistant for working out a piece of music from a recording. It offers many features aimed at making the transcription job smoother and easier, including the ability to slow down the music without changing its pitch, and to analyse chords and show you what notes are present.
wx12Ton helps one to work with music involving twelve-note series. In particular, it displays the 48 forms of a twelve-note series, and tests series for tonal phrases. In addition, wx12Ton allows the user to list the complete set of all twelve-note series which satisfy certain criteria.
DansTuner is a program to tell you if you are playing a pitch in tune. Major features include automatic discovery of which note you are trying to play (good for trumpet, singer, etc.), the ability to play a guide tone at a configurable volume, a graphical moving "needle" with a red/green display and detail about how flat or sharp you are, and an easily configurable background noise threshold.