Comparison of Transient-Evoked Otoacoustic Emission Waveforms and Latencies Between Nonlinear Measurement Techniques

The nonlinear differential technique is commonly used to remove stimulus artifact when measuring transient-evoked otoacoustic emissions (TEOAE). However, to ensure removal of stimulus artifact, the initial 2.5-ms of the sound pressure recording must be discarded. Discarding this portion of the response precludes measurement of TEOAE energy above approximately 5 kHz and may limit measurement of shorter-latency TEOAE components below 5 kHz. The contribution from short-latency components influences the overall latency of the emission, including its dependence on frequency and stimulus level. The double source, double-evoked technique provides an alternative means to eliminate stimulus energy from the TEOAE and permits retention of the entire response. This study describes the effect of measurement technique on TEOAE waveforms and latencies. TEOAEs were measured in 26 normal hearing subjects using the nonlinear differential and double source, double-evoked techniques. The nonlinear differential technique limited measurement of short-latency TEOAE components at frequencies as low as ~3 kHz. Loss of these components biased TEOAE latencies to later moments in time and reduced the dependence of latency on stimulus level and frequency. In studies investigating TEOAE latency, the double source, double-evoked technique is recommended as it permits measurement of the both long- and short-latency components of the TEOAE.