Measurement:Deflection of the Eardrum at Various Sound Levels

Deflection of the Eardrum at Various Sound Levels

If we make the assumption that the eardrum displacement is the same as that of the air striking it, we can write

where Din is the displacement in inches (the rms amplitude) of the air, Dcm is the displacement in centimeters, f is the frequency in hertz, and LP is the sound level in decibels referred to 0.00002 N/m2.

Example

What is the displacement of the eardrum in inches for a tone at 1000 Hz at a level of 74 dB? Using Eq. (2-51),

which is a displacement of approximately one-one-millionth of an inch (0.000001 in).