Band.js : An interface for the Web Audio API that supports rhythms, multiple instruments, repeating sections, and complex time signatures.
jsmad : jsmad is a pure javascript MP3 decoder, based on libmad, with an ID3 decoder written from scratch.
dancer.js : dancer.js is a high-level audio API, usable with both Mozilla's Audio Data API and Webkit's Web Audio API with flash fallback, designed to make sweet ...
Wave.js : Audio visualizer library for javascript. Create dynamic animations that react to an audio file or audio stream.
howler.js : howler.js is an audio library for the modern web. It defaults to Web Audio API and falls back to HTML5 Audio.
Fast, JavaScript DSP library that creates JIT optimized audio callbacks using code generation techniques.
It is designed to be a fast audio API for browser based audio content.