How do OAEs escape the cochlea?
In addition to the puzzle about the source of OAEs, the mode of propagation of OAEs from within the cochlea to the ear canal has not been completely determined. The mode of forward propagation of mechanical energy has traditionally been described using the traveling wave model. As researchers began to examine the minute details about OAEs generation and propagation, the general assumption was that OAEs travel out of the cochlea the same way energy travels into the cochlea, via a traveling wave. This mode of transmission would result in a delay in recording OAEs after initiating a stimulus tone. This delay would be approximately twice the delay for the stimulus to reach its characteristic frequency (CF) place in the cochlea. Evidence is available in support of this mode of OAE propagation (Shera et al., 2002), however, direct measurements of traveling-wave delays in live human ears are not possible. In laboratory animals, where measurements on live subjects are possible, parallel measur
