Evoked otoacoustic emissions: normative data and presbycusis.

Evoked acoustic emission (EAEs) recordings hold some promise as a fast, objective and non-invasive audiological procedure to study the cochlea at the outer hair cell (OHC) level. However, accurate interpretation in the EAE response must be based on a knowledge of its variations with age. In order to investigate age-related changes of EAEs, the properties of EAEs (incidence, threshold and spectrum) were studied in 151 ears from subjects whose age varied between 2 and 88 years. EAEs were present in 100% of the tested subjects until the age of 60 years. After this age, EAE incidence fell to 35%. EAE threshold did not vary until the age of 40 years but increased linearly after this age. Thus, complementary information on OHC degenerative changes in presbycusis could be deduced from these data.