title: Comparisons of transient evoked otoacoustic emissions using chirp and click stimuli.
abstract: Transient-evoked otoacoustic emission (TEOAE) responses (0.7-8 kHz) were measured in normal-hearing adult ears using click stimuli and chirps whose local frequency increased or decreased linearly with time over the stimulus duration. Chirp stimuli were created by allpass filtering a click with relatively constant incident pressure level over frequency. Chirp TEOAEs were analyzed as a nonlinear residual signal by inverse allpass filtering each chirp response into an equivalent click response. Multi-window spectral and temporal averaging reduced noise levels compared to a single-window average. Mean TEOAE levels using click and chirp stimuli were similar with respect to their standard errors in adult ears. TEOAE group delay, group spread, instantaneous frequency, and instantaneous bandwidth were similar overall for chirp and click conditions, except for small differences showing nonlinear interactions differing across stimulus conditions. These results support the theory of a similar generation mechanism on the basilar membrane for both click and chirp conditions based on coherent reflection within the tonotopic region. TEOAE temporal fine structure was invariant across changes in stimulus level, which is analogous to the intensity invariance of click-evoked basilar-membrane displacement data.
authors.affiliation: Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA.
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Keefe
authors.affiliation: National Center for Rehabilitative Auditory Research, Department of Veterans Affairs, Portland Health Care System, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA.
authors.forename: M Patrick
authors.initials: MP
authors.lastname: Feeney
authors.affiliation: Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, Ohio 45229, USA.
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Hunter
authors.affiliation: Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA.
authors.forename: Denis F
authors.initials: DF
authors.lastname: Fitzpatrick
mesh_terms: D000161:Acoustic Stimulation; D001489:Basilar Membrane; D005260:Female; D006801:Humans; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous