When using the Player.playNote(Location loc, Instrument instrument, Note note) and Player.playNote(Location loc, byte instrument, byte note) the sound output is garbage. I managed to trace down the problem to:
{{
public class CraftPlayer extends CraftHumanEntity implements Player
{
...
public void playNote(Location loc, byte instrument, byte note)

{ ... getHandle().playerConnection.sendPacket(new PacketPlayOutNamedSoundEffect("note." + instrumentName, loc.getBlockX(), loc.getBlockY(), loc.getBlockZ(), 3.0F, note)); // <-- bug in here }

...
public void playNote(Location loc, Instrument instrument, Note note)

{ ... getHandle().playerConnection.sendPacket(new PacketPlayOutNamedSoundEffect("note." + instrumentName, loc.getBlockX(), loc.getBlockY(), loc.getBlockZ(), 3.0F, note.getId())); // <-- bug in here }

}}