Note: AudioSprite is not a class, but its usage is easily lost in the documentation, so it has been called out here for quick reference.

Audio sprites are much like CSS sprites or image sprite sheets: multiple audio assets grouped into a single file. Audio sprites work around limitations in certain browsers, where only a single sound can be loaded and played at a time. We recommend at least 300ms of silence between audio clips to deal with HTML audio tag inaccuracy, and to prevent accidentally playing bits of the neighbouring clips.

Benefits of Audio Sprites:

• More robust support for older browsers and devices that only allow a single audio instance, such as iOS 5.
• They provide a work around for the Internet Explorer 9 audio tag limit, which restricts how many different sounds that could be loaded at once.
• Faster loading by only requiring a single network request for several sounds, especially on mobile devices where the network round trip for each file can add significant latency.

Drawbacks of Audio Sprites

• No guarantee of smooth looping when using HTML or Flash audio. If you have a track that needs to loop smoothly and you are supporting non-web audio browsers, do not use audio sprites for that sound if you can avoid it.
• No guarantee that HTML audio will play back immediately, especially the first time. In some browsers (Chrome!), HTML audio will only load enough to play through at the current download speed – so we rely on the canplaythrough event to determine if the audio is loaded. Since audio sprites must jump ahead to play specific sounds, the audio may not yet have downloaded fully.
• Audio sprites share the same core source, so if you have a sprite with 5 sounds and are limited to 2 concurrently playing instances, you can only play 2 of the sounds at the same time.

Example

    createjs.Sound.initializeDefaultPlugins();
    var assetsPath = "./assets/";
    var sounds = [{
        src:"MyAudioSprite.ogg", data: {
            audioSprite: [
                {id:"sound1", startTime:0, duration:500},
                {id:"sound2", startTime:1000, duration:400},
                {id:"sound3", startTime:1700, duration: 1000}
            ]}
        }
    ];
    createjs.Sound.alternateExtensions = ["mp3"];
    createjs.Sound.on("fileload", loadSound);
    createjs.Sound.registerSounds(sounds, assetsPath);
    // after load is complete
    createjs.Sound.play("sound2");

You can also create audio sprites on the fly by setting the startTime and duration when creating an new AbstractSoundInstance.

    createjs.Sound.play("MyAudioSprite", {startTime: 1000, duration: 400});

The excellent CreateJS community has created a tool to create audio sprites, available at https://github.com/tonistiigi/audiosprite, as well as a jsfiddle to convert the output to SoundJS format.