Serway & Jewett — Wave Motion: Problem 2

An entrepreneur is designing a new outdoor concert venue. He wants to procure loudspeakers that will provide a sound level of 83 dB at a location 100 m from the speakers. (a) What sound power output is required for the speakers? Assume that the sound radiates as a spherical wave and that there are no reflections from the ground. (b) After having someone perform the calculation in part (a) for him, the entrepreneur goes to the electronics store and purchases a speaker that the salesman tells him is rated at 150 W, which he thinks should clearly do what he needs. When he tests the speaker at the venue and turns the sound up to the maximum that the speaker can handle, however, the sound level at 100 m is only 70.8 dB. The angry entrepreneur runs to his attorney, who hires your team as expert witnesses to see if litigation is appropriate against the salesman. What is the power output of the speaker, based on the sound level data? (c) After performing some research on loudspeakers, argue that litigation should not be initiated against the salesman.