title: Stimulus ratio dependence of low-frequency distortion-product otoacoustic emissions in humans.
abstract: Active amplifiers within the cochlea generate, as a by-product of their function, distortion-product otoacoustic emissions (DPOAEs) in response to specific two-tone stimuli. Focus has been on invoking emissions in a mid-frequency range from ∼0.5 to 4 kHz. The present study investigates stimulus parameters of the DPOAE at 2f1-f2 frequencies below 0.5 kHz. Eighteen out of 21 young human adults screened had audiometrically normal hearing for inclusion in the experiment. DPOAEs were measured with pure-tone stimuli in four configurations: f2 fixed around 2.13 kHz, f2 fixed around 0.53 kHz, 2f1-f2 fixed at 1.23 kHz and 0.25 kHz. Eight stimulus ratios, f2/f1, and three stimulus sound pressure levels, L1/L2, were measured in each configuration. Trends in ratio-magnitude responses for the mid-frequency DPOAE agree with those reported in previous literature. DPOAEs are not limited to distortion frequencies >0.5 kHz, but the stimulus ratio invoking the largest DPOAE in the mid-frequency range does not do so in the low-frequency range. Guiding the ratio according to the equivalent rectangular bandwidth of auditory filters maintains the DPOAE level.
authors.affiliation: Acoustics, Department of Electronic Systems, Aalborg University, Aalborg, Denmark.
authors.forename: Anders T
authors.initials: AT
authors.lastname: Christensen
authors.affiliation: Acoustics, Department of Electronic Systems, Aalborg University, Aalborg, Denmark.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Ordoñez
authors.affiliation: Acoustics, Department of Electronic Systems, Aalborg University, Aalborg, Denmark.
authors.forename: Dorte
authors.initials: D
authors.lastname: Hammershøi
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D003051:Cochlea / Q000294:innervation*; D005260:Female; D006801:Humans; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous; D010898:Pitch Perception; D013018:Sound Spectrography; D055815:Young Adult