Chapter 12, Problem 30P

Two small speakers A and B are driven in step at 725 Hz by the same audio oscillator. These speakers both start out 4.50 m from the listener, but speaker A is slowly moved away. (See Figure 12.41.) (a) At what distance d will the sound from the speakers first produce destructive interference at the location of the listener? (b) If A keeps moving, at what distance d will the speakers next produce destructive interference at the listener? (c) After A starts moving away, at what distance will the speakers first produce constructive interference at the listener?

Figure 12.41 Problem 30.