WhiteNoise.js

function WhiteNoise(audioContext) {
    this.node = audioContext.createBufferSource();
    var bufferSize = 2 * audioContext.sampleRate,
        buffer = audioContext.createBuffer(1, bufferSize, audioContext.sampleRate),
        data = buffer.getChannelData(0);

    for (var i = 0, len = data.length; i < len; i++) {
        data[i] = Math.random() * 2 - 1;
    }

    this.node.buffer = buffer;
    this.node.loop = true;
}

var audioContext = new webkitAudioContext(),
    noise = new WhiteNoise(audioContext);

noise.node.connect(audioContext.destination);
noise.node.start(0);