Yet another sound visualizer program, with versions for X11 and Windows. An XMMS plugin also exists.

Synaesthesia displays sound as field of fog and glowing line. The sound looks like stars, "heat" or waves, with configurable outlook.

Synaesthesia seeks to provide not just a visual representation of sound, but a representation of how sound is perceived. Its display combines information about the frequency, location and diffuseness of sound.

The display is sufficiently detailed to make it possible to distinguish several individual instruments, singers, or special effects on screen by their location, shape and color, and sufficiently fast to distinguish individual drum beats and notes.

(From the web page)