Imagine you are in an open field where two loudspeakers are set up and connected to the same amplifier so that they emit sound waves in phase at 688 hz. take the speed of sound in air to be 344 m/s. if you are 3.00 m from speaker a directly to your right and 3.50 m from speaker b directly to your left. what is the shortest distance d you need to walk forward to be at a point where you cannot hear the speakers?