Abstract

OBJECTIVE: The purpose of this study was to investigate transiently evoked otoacoustic emissions recorded from the cochleas of neonates using three acquisition protocols: non-linear; linear; and QuickScreen. In the non-linear mode, a series of four clicks was used, with three clicks at the same level and polarity and a fourth at three times greater amplitude and inverted polarity. In the linear protocol, all stimuli were presented at the same level and polarity. Both modes used a 20 ms recording window, but the third QuickScreen screening mode used the non-linear click sequence and a shorter 12 ms window.

MATERIALS and METHODS: All responses were processed off-line with time-frequency algorithms, with the linear transiently evoked otoacoustic emissions additionally processed to eliminate linear artifacts in the initial few milliseconds of signal.

RESULTS: Short windows contained only a fraction of the transiently evoked otoacoustic emission, distorting its time-frequency structure. Analysis of the response level and signal to noise ratio suggested that recordings elicited by a linear protocol had an advantage in terms of signal to noise ratio.

CONCLUSION: The results indicate that screening protocols that use recording windows with a reduced length, such as QuickScreen, can only be used to detect the presence or absence of otoacoustic emission. Removing the stimulus artifact from linear transiently evoked otoacoustic emission responses improves response level and signal to noise ratio compared with the standard non-linear protocol.