Question

While at a party, you pull up a sound intensity level app on your phone (everyone does stuff like that, right?), and it reads 83 dB . You look around and count 40 people talking. If you assume that each person contributes the same amount of noise, determine the sound intensity level of one of those people talking.

Answer 1

Sound Intensity level is given by:

SL = 10*log (I1/I0)

SL = Sound level of 40 people = 83 dB

I0 = Human threshold intensity = 10^-12 W/m^2

I1 = Intensity of sound produced by 40 people = ?

I1 = I0*10^(SL/10) = 10^-12*10^(83/10)

I1 = 0.000199526231 W/m^2 = 1.995*10^-4 W/m^2

Intensity of sound produced by 1 person = I2 = I1/40 = 1.995*10^-4/40

I2 = 4.9875*10^-6

Now Sound intensity level of 1 person will be:

SL2 = 10*log (I2/I0)

SL2 = 10*log (4.9875*10^-6/10^-12)

SL2 = 66.9788 dB

sound intensity level of one of those people talking = 67 dB

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