Chapter 17, Problem 21P

SSM In Fig. 17-37, two speakers separated by distance d₁ = 2.00 m are in phase. Assume the amplitudes of the sound waves from the speakers are approximately the same at the listener’s ear at distance d₂ = 3.75 m directly in front of one speaker. Consider the full audible range for normal hearing, 20 Hz to 20 kHz. (a) What is the lowest frequency f_{min, 1} that gives minimum signal (destructive interference) at the listener’s ear? By what number must f_{min, 1} be multiplied to get (b) the second lowest frequency f_{min, 2} that gives minimum signal and the third lowest frequency f_{min, 3} that gives minimum signal? What is the lowest frequency f_{max, 1} that gives maximum signal (constructive interference) at the listener's ear? By what number must f_{max, 1} be multiplied to get (e) the second lowest frequency f_{max, 2} that gives maximum signal and (f) the third lowest frequency f_{max, 3} that gives maximum signal?

Figure 17-37 Problem 21.