Sound waves and eardrum problem

[thschica]

A 50 dB sound wave strikes an eardrum whose area is 4.1 * 10-5 m2.
(a) How much energy is absorbed by the eardrum per second?
W
(b) At this rate, how long would it take your eardrum to receive a total energy of 1.0 J?
years

I have tried to solve using I=2pi^2f^2A^2pv

and got f=280 ; v=343;p=1.29;I=1*10^-12 and A =1.28e-18 its wrong though

 

[Andrew Mason]

A 50 dB sound wave strikes an eardrum whose area is 4.1 * 10-5 m2.
(a) How much energy is absorbed by the eardrum per second?
W
(b) At this rate, how long would it take your eardrum to receive a total energy of 1.0 J?
years

I have tried to solve using I=2pi^2f^2A^2pv

and got f=280 ; v=343;p=1.29;I=1*10^-12 and A =1.28e-18 its wrong though

Decibels are a little tricky to work with. I think all you need to know is that $I = 10 log(P/P_0)$ where P is the power/area and $P_0 = 10^{-12} W/m^2$

AM