Halliday, Resnick & Walker — Waves–II: Problem 32

Approximately a third of people with normal hearing have ears that continuously emit a low-intensity sound outward through the ear canal. A person with such spontaneous otoacoustic emission is rarely aware of the sound, except perhaps in a noise-free environment, but occasionally the emission is loud enough to be heard by someone else nearby. In one observation, the sound wave had a frequency of 1665 Hz and a pressure amplitude of \(1.13 \times 10^{-3} \text{ Pa}\). What were (a) the displacement amplitude and (b) the intensity of the wave emitted by the ear?