Question

In our PHY131 class, there are 60 students enrolled. If we assume that one ringing cellphone produces a sound level of 70 dB, what would the sound level be if everyone's cellphone rang at the same time?

A) 90 dB
B) 100 dB
C) 110 dB
D) 120 dB

Answer 1

The combined sound level when 60 cellphones ring simultaneously would be closest to 90 dB (A), given that each individual phone produces a sound level of 70 dB and sound intensity levels increase logarithmically, not linearly, with multiple sources.

Step-by-step explanation:

The question asks for the combined sound level if all 60 students' cellphones rang at the same time, given that one cellphone produces a sound level of 70 dB. The increase in sound level can be calculated using the fact that a 10 dB increase represents a sound intensity 10 times greater.

Therefore, the sound level does not simply add up; it combines logarithmically. For every doubling of sound sources, the sound intensity level increases by about 3 dB. To find the combined sound level, we would calculate how many times the number of cellphones doubles from one cellphone to 60 cellphones. Since 26 is 64, slightly more than 60, we have approximately 6 doublings of the sound source, which would result in an increase of 6 x 3 dB = 18 dB. Adding this to the original 70 dB level gives us 88 dB, which is closest to option A (90 dB).