Natural Science Forum / Physics / Acoustics / March 2006

In my physics class we are having a discussion about how the eardrum
works. We understand that the eardrum vibrates and that vibration is
transferred through the ear and eventually interpreted as sound. Our
question is "Does the eardrum vibrate at every frequency from 20 Hz to
20000 Hz or does it have only certain frequencies in that range that it
vibrates at?" Some of the things that we do not understand are
1. Are all vibrations on the eardrum that cause sounds discernible by
the human standing waves? If they all are standing waves, what enables
the tympanum to have standing waves at frequencies continuous from 20
Hz to 20000 Hz. Unless you alter the length of a guitar string, it
certaintly can't have such a continuous range of vibrations.
2. Is the following analogy a good analogy. The human eardrum picks up
vibrations just like a guitar string will resonante when the right
frequency tuning fork is placed close enough to the guitar string. If
this is analogy holds, why can the guitar string only respond to a
couple of frequencies while the human ear drum will "resonate" with
every frequency between 20 and 20000 Hz.

We would appreciate any guidance. All of the websites that i have
looked at are more concerned with the cochlea then with how the eardrum
works.