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 344m/s. If you are 3.00m from speaker A directly to your right and 3.50 m from speaker B directly to your left, what is the shortest distance you need to walk forward to be at a point where you cannot hear the speakers?