Two small speakers A and B are driven in step
at 745 Hz by the same audio oscillator. These speakers
both start out 4.50 m from the listener, but speaker
A is slowly moved away. At what distance dd will the
sound from the speakers first produce destructive interference at
the location of the listener? If A keeps moving, at what
distance dd will the speakers next produce destructive
interference at the listener? After A starts moving away, at
what distance will the speakers first produce constructive
interference at the listener?