A pair of speakers separated by 0.900 m are driven by the same oscillator at a frequency of 672 Hz. An observer originally positioned at one of the speakers begins to walk along a line perpendicular to the line joining the speakers. (Assume the speed of sound is 345 m/s.)
(a) How far must the observer walk before reaching a relative maximum in intensity?
(b) How far will the observer be from the speaker when the first relative minimum is detected in the intensity?