1) At a distance of 30m from a jet engine, the sound intensity level is 130 dB.

Question

1) At a distance of 30m from a jet engine, the sound intensity level is 130 dB. Serious, permanent hearing damage occurs rapidly at intensity levels this high, which is why you see airport personnel using hearing protection out on the runway. Assume the engine is an isotropic source of the sound and ignore reflections and absorption. At what distance is the intensity level 30 dB - quiet library level? Is this realistic? What assumption are we making that is complete garbage?

answer: 3*106 m

2) what are the maximum pressure and displacement amplitudes our ear can tolerate? HINT: Threshold of Plain

answer: 28.7 Pa and 1.11*10-5 m

I need explanations!

Explanation / Answer

We know that,

I1/I2 = r2^2/r1^2

I1 = 130 dB = 10 w/m^2

I2 = 30 dB = 10^-9 W/m^2

r2 = ? ; r1 = 30

r2 = sqrt [(10 /10^-9 ) 30^3 ] = 3 x 10^6 m

Hence, r2 = 3 x 10^6 m

b)Threshold of pain = 123 dB = 2.05 W/m^2

we know that,

p = sqrt (I Z) ; Z = 400 N-s/m^3

p = sqrt (2.05 x 400) = 28.7 Pa

Hence, p = 28.7 Pa

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