I changed my code a little bit and now it gives this error:
Error in class 'LibraryLWJGLOpenAL'
2013-06-08 11:22:28 [iNFO] [sTDOUT] Unable to open file 'flute/track.ogg' in method 'loadSound'
2013-06-08 11:22:28 [iNFO] [sTDOUT] Error in class 'LibraryLWJGLOpenAL'
2013-06-08 11:22:28 [iNFO] [sTDOUT] Source 'sound_2' was not created because an error occurred while loading flute/track.ogg
2013-06-08 11:22:28 [iNFO] [sTDOUT] Error in class 'LibraryLWJGLOpenAL'
2013-06-08 11:22:28 [iNFO] [sTDOUT] Source 'sound_2' not found in method 'play'
I relocated the file to jars/bin/item/flute/track.ogg
The modified code:
Item:
world.playSoundEffect((double)x + 0.5D, (double)y + 0.5D, (double)z + 0.5D, "flute.track", 1.0F, world.rand.nextFloat() * 0.1F + 0.9F);
SoundHandler:
event.manager.soundPoolSounds.addSound("flute/track.ogg", Main.class.getResource("/item/flute/track.ogg"));
I hope this message helps