Question

At a rock concert, a dB meter registered 126 dB when placed 2.4 m in front of a loudspeaker on the stage.

Part A

What was the power output of the speaker, assuming uniform spherical spreading of the sound and neglecting absorption in the air?

Express your answer using two significant figures.

P =

  W  

Part B

How far away would the sound level be a somewhat reasonable 88 dB ?

Express your answers using two significant figures.

Answer 1

Sound level

Given that , Distance from the source of sound ,

Power output of speaker is

b) Sound level at a distance is