A function to convert numbers into sound.

playSparkline.js

// Licensed under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
// http://creativecommons.org/publicdomain/zero/1.0/

// Pass in an array of numbers ranging from 0 to 20.

function playSparkline(notes) {
    if (!window.AudioContext && !window.webkitAudioContext) {
        return;
    }
    var playing = null;
    var note = 0;
    var output = new (window.AudioContext || window.webkitAudioContext)();
    var instrument = output.createOscillator();
    var amplifier = output.createGain();
    var playNotes = function() {
        if (note < notes.length) {
            instrument.frequency.value = 440 + (notes[note] * 64); // hertz
            note = note + 1;
        } else {
            amplifier.gain.value = 0;
        }
        playing = window.setTimeout(playNotes, 25);
    };
    instrument.type = 'sine'; // 'sine', 'square', 'sawtooth', 'triangle'
    instrument.start();
    instrument.connect(amplifier);
    amplifier.gain.value = 0.7;
    amplifier.connect(output.destination);
    playNotes();
}

I was exploring the source code of your website, looking for microformats inspiration, when I spotted the code above. The audio API is interesting!

I noticed one thing though: playNotes never stops calling itself, even after the music stops. There's a return missing after line 20; alternatively line 22 can be moved into the if block:

    var playNotes = function() {
        if (note < notes.length) {
            instrument.frequency.value = 440 + (notes[note] * 64); // hertz
            note = note + 1;
            playing = window.setTimeout(playNotes, 25);
        } else {
            amplifier.gain.value = 0;
        }
    };