Question

Two loudspeakers face each other, vibrate in phase, and produce identical 406 Hz tones. A listener walks from one speaker toward the other at a constant speed and hears the loudness change (loud-soft-loud) at a frequency of 2.86 Hz. The speed of sound is 343 m/s. What is the walking speed

Answer 1

1.21 m/s

Step-by-step explanation:

Given :

2 loudspeakers

F2 - F1 = 2.86 Hz

Speed of sound, V = 343

Fo = frequency when listener is at rest = 406Hz

To obtain the walking speed Vo, speed as observer moves away from speaker ;

Vo = [(F2 - F1) * V] ÷ 2 * Fo

Vo = [2.86 * 343] ÷ (2 * 406)

Vo = 980.98 / 812

Vo = 1.2081034

Vo = 1.21 m/s