A student typing in a computer cluster generates a sound level of 55 dB. What will the dB level the night before essays are due when there are 30 equally noisy students working in the cluster?(adsbygoogle = window.adsbygoogle || []).push({});

dB_{o}= 55

I_{hearing}= 1E-12 W/m^{2}

B_{o}= 10log(I/I_{hearing})

55 = 10log(I/I_{hearing})

55 = 10log(I/1.0E-12)

I = 3.16227766E-7 W/m^{2}

If there are 30 other individuals, this makes a total of 31 individuals.

I_{total}= 31 x I = 31 x 3.16227766E-7

I_{total}= 9.80E-6 W/m^{2}

B_{total}= 10log(I_{total}/I_{hearing}) = 10log(9.80E-6/1E-12)

B_{total}= 69.91 dB ???

The answer says that it is 63.8 dB. Please can somebody help me find where in my logic I have failed? Thank you so very much everyone!

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# Homework Help: Sound intensity level, decibels

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