Interference: Two In-Phase Loudspeakers That Emit Sound with the Same

Multiple Choice

Interference: Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 8.00 m. A person is standing 12.0 m away from the wall, equidistant from the loudspeakers. When the person moves 3.00 m parallel to the wall, she experiences destructive interference for the second time. What is the frequency of the sound? The speed of sound in the room is 343 m/s. CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers.

A) 278 Hz
B) 422 Hz
C) 452 Hz
D) 562 Hz
E) 694 Hz