How Do You Calculate Pressure Amplitude and Force on an Eardrum from dB Level?

AI Thread Summary
To calculate the pressure amplitude of a sound wave at 124.5 dB, the relationship between intensity and pressure amplitude is used, leading to a pressure of approximately 33.576 N/m². The force exerted on an eardrum with an area of 0.520 x 10^-4 m² is calculated to be about 1.746 milliNewtons. Despite these calculations, the original poster is unsure if the answers are correct and seeks confirmation. The discussion highlights the importance of understanding the logarithmic relationship between sound intensity and pressure. Accurate calculations are crucial for determining the effects of sound on the human ear.
Jtappan
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Some one please help! Pressure Amplitude

Homework Statement

(a) What is the pressure amplitude of a sound wave with an intensity level of 124.5 dB in air?

_____ N/m2
(b) What force does this exert on an eardrum of area 0.520 10-4 m2?

_____ mN



3. The Attempt at a Solution


if P is amplitude of pressure, then sound intensity (I) is proportional to P^2
I/Io = (P/Po)^2
dB = sound intensity level = 10 log[I/Io]
124.5 = 10 log[I/Io] = 10 log[P/Po]^2 = 20 log(P/Po)
log(P/Po) = 124.5/20 = 6.225
P = Po [10]^6.225
Po = reference pressure amplitude for human ear = 2*10^-5 N/m^2
P = 2*10^-5*[10]^6.225
P = 33.576 N/m^2
----------------
Force on eardrum = P * area = 33.576*0.52*10^4 N
F = 1.746 milli N




This is what I did. But it is not giving me the correct answer...can anyone help me?
 
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This is pressure tactics, posting it three times.

33.5 N/m^2 seems to be correct. Are you getting both answers wrong?
 

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