Ok...so I don't know how to do this problem... Two speakers are driven by the same oscillator whose frequency is 200Hz. They are located on a vertical pole a distance of 4.00 m from each other. A man walks straight toward the lower speaker in a direction perpendicular to the pole. a) How many times will he hear a minimum in sound intensity? b) how far is he from the pole at these moments? Take speed of sound to be 330 m/s and ignore any sound reflections coming off the ground. I don't know how to start this problem so any help will be much appreciated!