Two loudspeakers are about 10 m apart in the front of a

Chapter 12, Problem 11MCQ

(choose chapter or problem)

Two loudspeakers are about 10 m apart in the front of a large classroom. If either speaker plays a pure tone at a single frequency of 400 Hz, the loudness seems pretty even as you wander around the room, and gradually decreases in volume as you move farther from the speaker. If both speakers then play the same tone together, what do you hear as you wander around the room?

(a) The pitch of the sound increases to 800 Hz, and the sound is louder but not twice as loud. It is louder closer to the speakers and gradually decreases as you move away from the speakers—except near the back wall, where a slight echo makes the sound louder.

(b) The sound is louder but maintains the same relative spatial pattern of gradually decreasing volume as you move away from the speakers.

(c) As you move around the room, some areas seem to be dead spots with very little sound, whereas other spots seem to be louder than with only one speaker.

(d) The sound is twice as loud—so loud that you cannot hear any difference as you move around the room.

(e) At points equidistant from both speakers, the sound is twice as loud. In the rest of the room, the sound is the same as if a single speaker were playing.