Joint Profile Characteristics of Long-Latency Transient Evoked and Distortion Otoacoustic Emissions

PURPOSE: In clinical practice, otoacoustic emissions (OAEs) are interpreted as either "present" or "absent." However, OAEs have the potential to inform about etiology and severity of hearing loss if analyzed in other dimensions. A proposed method uses the nonlinear component of the distortion product OAEs together with stimulus frequency OAEs to construct a joint reflection-distortion profile. The objective of the current study is to determine if joint reflection-distortion profiles can be created using long-latency (LL) components of transient evoked OAEs (TEOAEs) as the reflection-type emission. METHOD: LL TEOAEs and the nonlinear distortion OAEs were measured from adult ears. Individual input-output (I/O) functions were created, and OAE level was normalized by dividing by the stimulus level yielding individual gain functions. Peak strength, compression threshold, and OAE level at compression threshold were derived from individual gain functions to create joint reflection-distortion profiles. RESULTS: TEOAEs with a poststimulus window starting at 6 ms had I/O functions with compression characteristics similar to LL TEOAE components. The model fit the LL gain functions, which had R2 > .93, significantly better than the nonlinear distortion OAE gain functions, which had R2 = .596-.99. Interquartile ranges for joint reflection-distortion profiles were larger for compression threshold and OAE level at compression threshold but smaller for peak strength than those previously published. CONCLUSIONS: The gain function fits LL TEOAEs well. Joint reflection-distortion profiles are a promising method that could enhance diagnosis of hearing loss, and use of the LL TEOAE in the profile for peak strength may be important because of narrow interquartile ranges. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.20323593.