The Snack sound extension adds commands to play and record audio. Snack supports in-memory sound objects, file based audio, and streaming audio, with background audio processing. It handles fileformats such as AIFF, AU, MP3, NIST/Sphere, and WAV. Snack is extensible; new commands and sound file formats can be added using the Snack C-library. Snack also does sound visualization, e.g. waveforms and spectrograms. The visualization canvas item types update in real time and can output postscript. Works with Tcl 8.0.3 and later, as well as is stubs enabled. Works with the Tcl plug-in. Platforms: HP-UX, Irix, Linux, Solaris, Windows 95/98/NT/2000/XP.