OAE or otoacoustic emission testing (see here for introductory material) is the recording of sounds that the ear produces itself. Otoacoustic emissions were first reported by Kemp in 1978. They appear to be generated by motile elements in the cochlear outer hair cells. This youtube link shows a movie of one moving.
The OAE devices used in most clinics are "screeners". The typically check 5-10 frequencies and report whether the signal/noise ratio exceeds a preset limit, in which it indicates that the ear is a "pass", or if not, a "refer". This "go/no-go" type of output is often helpful in deciding whether there is any hearing problem -- people who "pass" at all frequencies are unlikely to have anything seriously wrong with their inner ear. OAE's are quick and not bothersome to patients.
|Sweep OAE -- This device, used in our clinic in Chicago, plots the difference between the noise floor and DPOAE response continously, between 750 and 16000 Hz. This normal person had good OAE's at all frequences up to roughly 8000 Hz.|
The one used above can scan the entire spectrum of OAE's, possibly finding areas of drop-out which might go undetected otherwise. This device was developed by Dr. Sumit Dhar (Shaffer, Withnell et al. 2003; Dhar and Abdala 2007; Dhar, Abel et al. 2009). A similar device was recently reported in use by Prieve et al (2019).
Prieve et al (2019) reported on 45 ears using a sweep device similar to that used in our clinical practice in Chicago (where we have done 1000's of studies). They reported "Significant correlations were found between the generator component and hearing threshold but not between reflection levels and hearing threshold. Most ears with normal hearing had both components, but only a small number of ears with hearing loss had both components."