Using spontaneous otoacoustic emissions to probe frequency selectivity

Spontaneous otoacoustic emissions (SOAEs) are present in all classes of vertebrates. Suppressing SOAEs allows us to evaluate the frequency selectivity of different animal species. The great advantage of SOAE-suppression measurements is that no response from the individual is needed. Thus, this method does not require training or active participation of the test subject.
In barn owls, neural tuning does not directly represent the frequency selectivity as measured by SOAE suppression. This leads to the assumption that the results of the different methods for testing frequency selectivity are not directly comparable.
Acoustic training effects due to language acquisition are not associated with differences of cochlear tuning, as the frequency tuning between Asian tonal language native speakers and Caucasian non-tonal native speakers was similar when being measured by SOAE suppression. Also, between participants with and without SOAEs, the frequency selectivity at the cochlear level was not significantly different, nor did they perform group-specifically differently in behavioral tests.
During acoustical measurements, complex interactions of SOAEs with each other and with external tones can occur. Such interactions can influence the participant's perception of a tone and should therefore be considered when measuring frequency tuning behaviorally.