SoundManager2 JS api, but uses flash for playing audio, providing spectrum data. has experimental HTML5 branch.
SoundJS A JavaScript sound loading, playing and layering library designed for browser-based games to have a multi-layering sound API.
audiolib.js normalizing library between the two audio APIs
has effects, synthesis, envelopes, recording and exporting
XAudioJS shim for basic audio handling between the two apis
grant wrote an HTML5 emulator of GameBoyColor to HTML5 and uses the audio apis there
dynamicaudio.js Moz Audio Data API polyfill via flash.
also an author of a nintendo emulator
audionode.js polyfill of Web Audio API using the moz audio data api.
done back in july so it may not still be compatible..
corban is one of the guys on the mozilla audio/webgl demo team
audiodata abstraction layer for audio data api
beatdetektor.js detects beats... and uses...
dsp.js for its DSP action, and can work with both APIs
Audiolet library for synthesis and composition with support for both APIs
music.js generates notes, intervals, chords, and scales across both APIs
jsmad mp3 decoder, or rather:
MPEG-1 demuxer
MPEG-1 Layer III decoder
ID3v2 reader
Will eventually be split into io.js, mpeg1.js, mp3.js and id3v2.js
Buzz A Javascript HTML5 Audio library
Alac.js - An Apple Lossless decoder in the browser
howler.js defaults to Web Audio and falls back to HTML5 Audio
ion.Sound Small plugin for playing sounds on events
quicksound.js small library, defaults to Web Audio API and falls back to Flash
timbre.js JavaScript Library for Objective Sound Programming, synthesis, functional processing
JPC2000 - Chrome only