The menu provides an option to turn music on and off, but not sound effects.  The only way I can turn sound effects off is to go into my phone's settings menu and turn the media volume all of the way to zero. Even putting the phone in silent mode won't turn off the sound effects because silent mode still lets media sounds play (it only silences rings and alerts). There are plenty of situations where people would want the game to be completely silent, so it would be nice if there was an option in the menu to turn the sound effects on and off as well.