Basic characteristics of click-evoked otoacoustic emissions in infants and children.

Since Kemp [J. Acoust. Soc. Am. 64, 1386-1391 (1978)] first described click-evoked otoacoustic emissions (COAEs), researchers have advocated their use as an excellent tool for diagnosing hearing loss in infants and children. However, there are few detailed reports of COAEs in this population, and those that do exist suggest that there are age-dependent differences. The purpose of the current study was to determine basic characteristics of COAEs in infants, toddlers, children, and young adults and to define any differences among age groups. An additional goal was to ensure that spontaneous otoacoustic emissions (SOAEs) did not confound any possible developmental effects. COAEs and SOAEs were measured from one ear of 223 normal-hearing subjects. COAE input/ output functions indicated that children aged less than one year have higher COAE levels than older children and adults. Children aged 1-5 yr had higher COAE levels than those aged 12-17 yr and adults. These differences were independent of level and SOAE status, but were dependent on frequency. The results of this study suggest that different clinical norms may be necessary for children aged less than 6 years.