Sound is detected when a sound wave causes the eardrum to vibrate. Typically, the diameter of the eardrum is about 8.4 mm in humans. How much energy is delivered to your eardrum each second when someone whispers 20dB a secret in your ear?

1 answer

Multiply the eardrum area by the sound intensity (Power/Area) that corresponds to 20 dB. It is a factor of 100 above the 0 dB reference level of 10^-12 W/m^2.

See http://en.wikipedia.org/wiki/Sound_intensity
for further details