A 40-db sound wave strikes an eardrum whose area is 5.0x10^-5 m². A)How much energy is absorbed by the eardrum

Question

per second? B)At this rate, how long would it take yur eardrum to recieve a total energy of 1.0J? Please show work! Thank you*

Answer 1

See the ref. Decibels are an expression of sound intensity (power/area) relative to a reference value.
Db = 10*log10(I/I0), where I = intensity and I0 = ref. intensity
I0 = 1E-12 w/m^2
At 40 db, log10(I/I0) = 4; I/I0 = 1E-^4; I = 1E-4*1E-12 = 1E-8 w/m^2
Sound power = intensity*area = 1E-8 w/m^2 * 5E-5 m^2 = 5E-13 w or 5E-13 J/s. (ans. A)
You can work out ans. B from this.
For some reason I keep getting an error when I try to include the reference web page link. It's at the hyperphysics site, go to sound/measurement/intensity.