This ActionScript class makes dealing with sounds in Starling very easy and intuitive: once you add a sound to the SoundManager you can easily play it, stop it, change its volume, fade it in, fade it out or cross-fade it with another sound.See more details and usage examples below, in the first comment.

SoundManager.as

package starling.extensions {

	import flash.events.Event;
	import flash.media.Sound;
	import flash.media.SoundChannel;
	import flash.media.SoundTransform;
	import flash.utils.Dictionary;
	import starling.core.Starling;

	public class SoundManager {

		private static var _instance:SoundManager;
		private var _isMuted:Boolean = false;		// When true, every change in volume for ALL sounds is ignored

		public var sounds:Dictionary;			// contains all the sounds registered with the Sound Manager
		public var currPlayingSounds:Dictionary;	// contains all the sounds that are currently playing

		public function SoundManager() 
		{			
			sounds = new Dictionary();
			currPlayingSounds = new Dictionary();
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		public function dispose():void {			
			sounds = null;
			currPlayingSounds = null;
		}
		// -------------------------------------------------------------------------------------------------------------------------			
		/** Add sounds to the sound dictionary */
		public function addSound(id:String, sound:Sound):void {
			sounds[id] = sound;
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Remove sounds from the sound manager */
		public function removeSound(id:String):void {
			if (soundIsAdded(id)) {
				delete sounds[id];				
				if (soundIsPlaying(id))
					delete currPlayingSounds[id];
			}
			else {
				throw Error("The sound you are trying to remove is not in the sound manager");
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Check if a sound is in the sound manager */
		public function soundIsAdded(id:String):Boolean {
			return Boolean(sounds[id]);
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Check if a sound is playing */
		public function soundIsPlaying(id:String):Boolean {
			for (var currID:String in currPlayingSounds) {
				if ( currID == id )
					return true;
			}	
			return false;
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Play a sound */
		public function playSound(id:String, volume:Number = 1.0, repetitions:int = 1, panning:Number = 0):void {			
			
			if (soundIsAdded(id))
			{
				var soundObject:Sound = sounds[id];
			
				var channel:SoundChannel = new SoundChannel();
				
				channel = soundObject.play(0, repetitions);
				
				if (!channel)
					return;
					
				channel.addEventListener(Event.SOUND_COMPLETE, removeSoundFromDictionary);
				
				// if the sound manager is muted, set the sound's volume to zero
				var v:Number = (_isMuted)? 0 : volume;
				var s:SoundTransform = new SoundTransform(v, panning);
				channel.soundTransform = s;

				currPlayingSounds[id] = { channel:channel, sound:soundObject, volume:volume };
			}
			else
			{
				throw Error("The sound you are trying to play (" + id + ") is not in the Sound Manager. Try adding it to the Sound Manager first.");
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Remove a sound from the dictionary of the sounds that are currently playing */
		private function removeSoundFromDictionary(e:Event):void {			
			
			for (var id:String in currPlayingSounds) 
			{
				if (currPlayingSounds[id].channel == e.target)
					delete currPlayingSounds[id];
			}
			e.currentTarget.removeEventListener(Event.SOUND_COMPLETE, removeSoundFromDictionary);
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Stop a sound */
		public function stopSound(id:String):void {			
			if (soundIsPlaying(id))
			{
				SoundChannel(currPlayingSounds[id].channel).stop();				
				delete currPlayingSounds[id];				
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------
		/** Stop all sounds that are currently playing */
		public function stopAllSounds():void {
			for (var currID:String in currPlayingSounds) 
				stopSound(currID);
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Set a sound's volume */
		public function setVolume(id:String, volume:Number):void {			
			if (soundIsPlaying(id))
			{
				var s:SoundTransform = new SoundTransform(volume);
				SoundChannel(currPlayingSounds[id].channel).soundTransform = s;
				currPlayingSounds[id].volume = volume;
			}
			else
			{
				throw Error("This sound (id = " + id + " ) is not currently playing");
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------
		/** Tween a sound's volume */
		public function tweenVolume(id:String, volume:Number = 0, tweenDuration:Number = 2):void {
			if (soundIsPlaying(id))
			{
				var s:SoundTransform = new SoundTransform();
				var soundObject:Object = currPlayingSounds[id];
				var c:SoundChannel = currPlayingSounds[id].channel;
				
				Starling.juggler.tween(soundObject, tweenDuration, {
					volume: volume,
					onUpdate: function():void {
						if (!_isMuted)
						{
							s.volume = soundObject.volume;
							c.soundTransform = s;
						}
					}
				});
			}
			else
			{
				throw Error("This sound (id = " + id + " ) is not currently playing");
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Cross fade two sounds. N.B. The sounds that fades out must be already playing */
		public function crossFade(fadeOutId:String, fadeInId:String, tweenDuration:Number = 2, fadeInVolume:Number = 1, fadeInRepetitions:int = 1):void {			
			
			// If the fade-in sound is not already playing, start playing it
			if (!soundIsPlaying(fadeInId))
				playSound(fadeInId, 0, fadeInRepetitions);
			
			tweenVolume (fadeOutId, 0, tweenDuration);
			tweenVolume (fadeInId, fadeInVolume, tweenDuration);
			
			// If the fade-out sound is playing, stop it when its volume reaches zero
			if (soundIsPlaying(fadeOutId))
				Starling.juggler.delayCall(stopSound, tweenDuration, fadeOutId);
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Sets a new volume for all the sounds currently playing 
		*  @param volume the new volume value 
		*/
		public function setGlobalVolume(volume:Number):void {
			var s:SoundTransform;
			for (var currID:String in currPlayingSounds) {
				s = new SoundTransform(volume);
				SoundChannel(currPlayingSounds[currID].channel).soundTransform = s;
				currPlayingSounds[currID].volume = volume;
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		/** Mute all sounds currently playing.
		*  @param mute a Boolean dictating whether all the sounds in the sound manager should be silenced (true) or restored to their original volume (false). 
		*/ 
		public function muteAll(mute:Boolean = true):void {

			if (mute != _isMuted)
			{
				var s:SoundTransform;
				for (var currID:String in currPlayingSounds) 
				{
					s = new SoundTransform(mute ? 0 : currPlayingSounds[currID].volume);
					SoundChannel(currPlayingSounds[currID].channel).soundTransform = s;
				}
				_isMuted = mute;
			}
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		public function getSoundChannel(id:String):SoundChannel {			
			if (soundIsPlaying(id))
				return SoundChannel(currPlayingSounds[id].channel);
				
			throw Error("You are trying to get a non-existent soundChannel. Play the sound first in order to assign a channel.");
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		public function getSoundTransform(id:String):SoundTransform {			
			if (soundIsPlaying(id))
				return SoundChannel(currPlayingSounds[id].channel).soundTransform;

			throw Error("You are trying to get a non-existent soundTransform. Play the sound first in order to assign a transform.");
		}
		// -------------------------------------------------------------------------------------------------------------------------		
		public function getSoundVolume(id:String):Number {			
			if (soundIsPlaying(id))
				return currPlayingSounds[id].volume;

			throw Error("You are trying to get a non-existent volume. Play the sound first in order to assign a volume.");
		}		
		// --------------------------------------------------------------------------------------------------------------------------------------
		// SETTERS & GETTERS
		public function get isMuted():Boolean { return _isMuted; }		
	}
}

Hi René!
Sorry for the late reply, I just noticed your comment - for some reason Gist doesn't notify me of new comments.
I see you point and it's a good one, I'll look into it and modify the setGlobalVolume() method the way you have suggested.

Thanks for the feedback,
Francesco

Hi,

Is there a way to add a Sound by passing the mp3 file path ? This would be very convenient in order to stream sound.