In the figure, two speakers separated by distance d = 1.90 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 = 3.95 m directly in front of one speaker. Consider the full audible range for

normal hearing, 20 Hz to 20 kHz and use 343 m/s for the speed of sound in air.

(a) What is the lowest frequency that gives minimum signal (destructive interference) at the listener's ear?

(b) What is the second lowest frequency that gives minimum signal?

(c) What is the third lowest frequency that gives minimum signal?

(d) What is the lowest frequency that gives maximum signal (constructive interference) at the listener's ear?

(e) What is the second lowest frequency that gives maximum signal?

(f) What is the third lowest frequency that gives maximum signal?