Solving Sound Wave Question: Energy Delivered to Eardrum

[stuti911]

Homework Statement

Sound is detected when a sound wave causes the eardrum to vibrate. Typically, the diameter of the eardrum is about 8.4mm in humans. When someone speaks to you in a normal tone of voice, the sound intensity at your ear is approximately 1 * 10^-6 W/m^2. How much energy is delivered to your eardrum each second?

Homework Equations

I = P/(4pi*r^2)

The Attempt at a Solution

I tried using the equation and I got 2.20×10^−10 W as my answer, but it is wrong. I cannot understand why, because the question seems really simple.
Any help is appreciated, thanks!

 

[collinsmark]

I tried using the equation and I got 2.20×10^−10 W as my answer, but it is wrong. I cannot understand why, because the question seems really simple.
Any help is appreciated, thanks!

The diameter of the eardrum is about 8.4 mm. Which means the radius is half that.

[Edit: And welcome to Physics Forums!]

 

[supratim1]

yes, so if you take proper radius you will get the answer.

 

[stuti911]

yes, i did take the radius
this is my calculation:
(10^-6)*(0.00001764*4*pi) which gives my the answer above
can any of you try the question?
thanks!

 

[supratim1]

isn't the answer 5.54*10^(-11)W ?

 

[supratim1]

first of all, take eardrum as a circle, not sphere, and so use area as pi*r^2

 

[stuti911]

allright.. i got it!
thanks a whole bunch :)

 

[supratim1]

welcome Stuti...would you accept my friend request?

 

[Mandeep Deka]

welcome Stuti...would you accept my friend request?

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