Howler.JS + Angular - path for playing sound file

I'm trying to play mp3 file in cordova + ionic hybrid app.

Sound is stored in:

www/sounds/dubstep/sound.mp3

And i'm trying to play file from service placed in /www/scripts/services/global.js using following code:

var sound = new Howl({
                    src: ['sounds/dubstep/sound.mp3'],
                    onend: function() {
                        console.log('Finished!');
                    },
                    onloaderror: function() {
                        console.log('Error!');
                    },
                });

                sound.play();

But it is always throwing onloaderror.

How i should set path in right way?

Thanks for any help.