Sound fade out

Sure.

Here is an example of how to fade the sound in and out.

I know it will look 'too much" at a first glance, but I'm giving you an approach I use in real world projects. I could've only copied and official example of the docs and adapted to you, but it would not be enough, IMO.

To give you a more direct answer:

- Just call the playSound function like this: exportRoot.playSound("gas", "bgm");

- Then fade it with a tween: createjs.Tween.get(exportRoot.playlist[exportRoot.sounds["gas"].id]).to({volume:0}, 2000);

JavaScript code:

this.soundCount = 0;
this.playlist = {};
// SETTINGS
// path to where the sounds are stored
this.folders =
{
    bgm:"sounds/bgm/",
    sfx:"sounds/sfx/"
}
// sounds settings. You're gonna play and fade sounds using their "id" property
this.sounds =
{
    city:  {type:"bgm",  id:"city",  file:"City_Plaza.mp3",                   volume:0.5},
    trip:  {type:"bgm",  id:"trip",  file:"Easy_Trip_Trap.mp3",               volume:0.6},
    gas:   {type:"bgm",  id:"gas",   file:"Gas_Pedal.mp3",                    volume:0.6},
    bonus: {type:"sfx",  id:"bonus", file:"190019__aiwha__hit-on-wood-3.wav", volume:0.4}
};
// FUNCTIONS
this.start = function()
{
    exportRoot.loadSounds();
};
// sounds need to be loaded before trying to play them
this.loadSounds = function()
{
    createjs.Sound.registerPlugins([createjs.WebAudioPlugin]);
    createjs.Sound.alternateExtensions = ["mp3"];
    createjs.Sound.on("fileload", exportRoot.soundLoaded, exportRoot);
    for (var key in exportRoot.sounds)
          createjs.Sound.registerSound(exportRoot.folders[exportRoot.sounds[key].type] + exportRoot.sounds[key].file, exportRoot.sounds[key].id);
};
// this is something I never know if I'm doing right. Because we have to play the sounds and immediately stop them so it can be availabe and stored in a variable
// for future references. I dunno if there's a way of doing this without playing the sound first. We also check if the number of sounds loaded is equal to the number
// of sounds we set in the 'sounds' property so we can be sure that the app can be started
this.soundLoaded = function(e)
{
    exportRoot.playlist[e.id] = createjs.Sound.play(e.id);
    exportRoot.playlist[e.id].volume = exportRoot.sounds[e.id].volume;
    exportRoot.playlist[e.id].stop();
    exportRoot.soundCount++;
    if (exportRoot.soundCount == exportRoot.getTotalSounds())
          exportRoot.allSoundsReady();
};
// convenience function to play sounds by passing at least the sound id and the type. The type is important (in our case "bgm" and "sfX") because we don't want to stop a BGM
// when we play a SFX
this.playSound = function(soundName, type, loop = 0, soundToStop = "", volume = 1)
{
    if (soundToStop)
         exportRoot.stopSound(soundToStop);
    exportRoot.playlist[exportRoot.sounds[soundName].id].play({interrupt:createjs.Sound.INTERRUPT_ANY, loop:loop, volume:volume});
};
// convenience function to stop a sound
this.stopSound = function(soundName)
{
    exportRoot.playlist[soundName].stop();
};
// convenience function to get the total of sounds in the "sounds" property
this.getTotalSounds = function()
{
    return Object.keys(exportRoot.sounds).length;
};
// function called when all sounds are ready. It's here that we call all code that needs the sounds to be available
this.allSoundsReady = function()
{
    exportRoot.fadeInButton.on("click", function(e)
    {
          createjs.Tween.get(exportRoot.playlist[exportRoot.sounds["gas"].id]).to({volume:1}, 2000);
    }, exportRoot);
    exportRoot.fadeOutButton.on("click", function(e)
    {
          createjs.Tween.get(exportRoot.playlist[exportRoot.sounds["gas"].id]).to({volume:0}, 2000);
    }, exportRoot);
    exportRoot.playSound("gas", "bgm");
};
// here we initialize the app
this.start();

FLA download:

animate_cc_html5_fade_out_sound.zip - Google Drive

I hope it all make sense.

Regards,

JC