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.

As the person walks towards the pole , his distance from the pole when he first hears a minimum in sound intensity is nearly

Options

A. 14.6m
B. 17.9m
C. 10.1m
D. 22.4m

Answer

B