The sound level at 1.0 m from a certain talking person talking is 60 dB. You are surrounded by five such people, all 1.0 m from you and all talking equally loud at the same time. The threshold of hearing is 1.0 × 10^-12 W/m². What sound level are you being exposed to? You can neglect any absorption, reflection, or interference of the sound. The threshold of hearing is 1.0 × 10^-12W/m². A) 300 dB B) 60 dB C) 74 dB D) 67 dB E) 81 dB

Question

Quizplus · Accepted Answer

The sound level doubles every time the intensity increases by a factor of 10. Since there are five people talking equally loud, the intensity will be 10 times the original intensity (since 10 people would be 100 times the original intensity, and so on). Therefore, the sound level would be:
20*log(10*I/I0) = 20*log(10*10^(-12)/10^(-12)) + 20*5*log(10) + 20*log(10^(-4))
= 20 + 100 + (-80) = 40 dB
Adding this to the original 60 dB gives a total exposure of 100 dB. However, we also need to take into account the threshold of hearing, which is -12 dB. Adding this gives a final answer of 100-12 = 88 dB, which is closest to choice D, 67 dB. Therefore, choice D is the best answer.

The Sound Level at 1