Calculating Energy Absorption by an Eardrum Exposed to Sound Waves

[jmb07]

A sound wave with intensity of 80.1 dB is incident on an eardrum of Area = 0.7x10^-4. How much energy is absorbed by the eardrum in 4 minutes?


I know this much... Power = (Intensity)(Area)..so...P=(80.1)(0.7x10^-4)

and Energy = (power)(time) so...E = (80.1)(0.7x10^-4)(240 sec) = 1.35


However, this is not the correct answer. Am i not doing the right conversions or what?? What looks wring here? (the correct answer is 1.72)

 

[mohd_adam]

E = (80.1) ( dB ) (0.7x10^-4)(240 sec)

I think that you must change unit db

 

[jmb07]

Yea I thought about that but i would have no idea how to convert dB to Hz or whatever it needed to be.
Any thoughts??

 

[mohd_adam]

try this ,

LI = 10 log( I / I0 ).

http://answers.yahoo.com/question/index?qid=20071011082631AALODJ6

 

[jmb07]

I'm a little confused about how to use this equation. I looked at the example on yahoo over and over but can't seem to figure out where some of those numbers are coming from.