title: Distortion-product otoacoustic emission suppression tuning curves in hearing-impaired humans.
abstract: Distortion-product otoacoustic emission (DPOAE) suppression tuning curves (STCs) were measured in 65 hearing-impaired (HI) subjects at f(2) frequencies of 2.0, 2.8, 4.0, and 5.6 kHz and L(2) levels relative to sensation level (SL) from 10 dB to as much as 50 dB. Best frequency, cochlear-amplifier gain (tip-to-tail difference, T-T), and tuning (Q(ERB)) were estimated from STCs. As with normal-hearing (NH) subjects, T-T differences and Q(ERB) decreased as L(2) increased. T-T differences and Q(ERB) were reduced in HI ears (compared to normal) for conditions in which L(2) was fixed relative to behavioral threshold (dB SL). When STCs were compared with L(2) at constant sound pressure levels (dB SPL), differences between NH and HI subjects were reduced. The large effect of level and small effect of hearing loss were both confirmed by statistical analyses. Therefore, the magnitude of the differences in DPOAE STCs between NH and HI subjects is mainly dependent on the manner in which level (L(2)) is specified. Although this conclusion may appear to be at odds with previous, invasive measures of cochlear-response gain and tuning, the apparent inconsistency may be resolved when the manner of specifying stimulus level is taken into account.
authors.affiliation: Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA.
authors.forename: Alyson
authors.initials: A
authors.lastname: Gruhlke
authors.forename: Cori
authors.initials: C
authors.lastname: Birkholz
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Neely
authors.forename: Judy
authors.initials: J
authors.lastname: Kopun
authors.forename: Hongyang
authors.initials: H
authors.lastname: Tan
authors.forename: Walt
authors.initials: W
authors.lastname: Jesteadt
authors.forename: Kendra
authors.initials: K
authors.lastname: Schmid
authors.forename: Michael P
authors.initials: MP
authors.lastname: Gorga
mesh_terms: D000161:Acoustic Stimulation; D000704:Analysis of Variance; D001307:Auditory Perception; D001309:Auditory Threshold; D016022:Case-Control Studies; D003051:Cochlea / Q000503:physiopathology*; D006311:Hearing Disorders / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D017084:Otoacoustic Emissions, Spontaneous; D010470:Perceptual Masking; D019986:Persons with Hearing Disabilities / Q000523:psychology; D011312:Pressure