An oscillator of frequency `680 Hz` drives two speakers . The speakers are fixed on a vertical pole at a distance `3 m` from each other as shown in Fig. 7.103. A person whose height is almost the same as that of the lower speaker walks towards the lower speaker in a direction perpendicular to the pole. Assuming that there is no reflection of sound from the ground and speed of sound is `v = 340 m//s` , answer the following questions.

How far is the person from the pole when he hears a minimum in sound intensity a second time ?

Options

A. 5.6 m
B. 7.8 m
C. 12.4 m
D. 17.6m

Answer

A