Pressure Amplitude Calculation for Sound Waves

[akan]

Homework Statement

What is the pressure amplitude in sound wave with intensity level of 65 dB?

The Attempt at a Solution

My textbook does not provide any instruction on how pressure amplitude is related to the intensity level. It does not even define what pressure amplitude is. While I can calculate the intensity (P/A) from decibels, I do not know how to calculate pressure amplitude. Please help.

 

[mgb_phys]

Read through this http://en.wikipedia.org/wiki/Sound_pressure
If you need to understand dB a little better see here http://en.wikipedia.org/wiki/Decibel

 

[akan]

Ok, so here's my attempt at solution..
I = POWER/AREA = FORCE * VELOCITY / AREA
PRESSURE = FORCE/AREA
PRESSURE = I / VELOCITY.
Since we are talking about sound, I suppose it is PRESSURE = I / V_SOUND (340), where I calculated I to be (I_0) (10^6.5).
But this doesn't seem to give the right answer (according to the answer key). What's the issue here?