Two speakers are driven by the same oscillator whose frequency is 140 Hz. They are located on a vertical pole a distance of 4.45 m apart 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 the speed of sound to be 330 m/s and ignore any sound reflections coming off the ground. (Give the first distances at which this happens.)