javoice: See with sound – see with your ears! Free soundscape synthesizer and sequencer! This fully interactive page allows you to draw your own 64 × 64, 16 grey-tone image and immediately hear the corresponding 64-voice polyphonic visual sound being synthesized on the fly! See and hear how The vOICe mapping works for your input. The 64-channel sound synthesis maps the image into an exponentially distributed frequency interval for a one second visual sound.

Furthermore, you can view sound waves, sonify existing images, train for audiovisual synesthesia, perform on-line composing, make visual sound animations and create spectrograms (sonograms, sonagrams).

The vOICe mapping: vertical positions of points in a visual sound are represented by pitch, while horizontal positions are represented by left-to-right scanning and corresponding stereo panning. Brightness is represented by loudness. In this manner, pixels become… voicels!

More here.