The creation of distortion products through the interaction of spontaneous otoacoustic emissions and externally generated tones.

Persistent Link:
http://hdl.handle.net/10150/187105
Title:
The creation of distortion products through the interaction of spontaneous otoacoustic emissions and externally generated tones.
Author:
Norrix, Linda Weiland.
Issue Date:
1995
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
A spontaneous otoacoustic emission (SOAE) and external tones (XTs) were used as primaries f₂ and f₁, respectively (frequency of f₂ > f₁) to create 2f₁-f₂ distortion products (DPOAEs). The DPOAEs primarily reflect active processes in the cochlea because low- to medium-level primaries less than 60 dB SPL were employed. DPOAE characteristics were determined and compared to what is known from the literature about DPOAEs created using two XTs. SOAE frequency and amplitude were also described. One hundred twenty-two women were screened for the presence of SOAEs to obtain 10 subjects for the study. XTs were presented to the ear at SOAE/f₁ ratios between 1.08 and 1.22. Sound pressure levels were incremented in 5 dB steps and extended from levels equal to the initial SOAE amplitudes to levels at which the SOAEs and DPOAEs disappeared into the noise floor. Amplitude and frequency of the SOAE, XT, and DPOAE were recorded by placing a low-noise microphone in the ear canal and extracted using Fast Fourier Transform analysis. Results indicated that the DPOAE amplitudes and SOAE suppression characteristics were variable across subjects. Despite the variability, the following trends were noted: (1) at larger frequency ratios, DPOAE generation and SOAE suppression were associated with greater XT levels; (2) DPOAE growth functions were characterized by slopes less than 1 dB/dB, a maximum, rollover and disappearance into the noise floor with increasing XT levels; (3) maximum amplitude DPOAEs were observed at frequencies approximately one-half octave lower than the SOAE; (4) DPOAE thresholds were associated with little SOAE suppression whereas the maximum DPOAEs were associated with a greater amount of SOAE suppression; (5) the most common SOAE frequency shift, in the presence of XT stimulation, was a shift to a higher frequency just prior to total SOAE suppression. Results are interpreted using an electrical circuit model (modified from Yates, 1990) and pictorial representations of the SOAE, XT, and DPOAE vibrational patterns on the basilar membrane (modified from Yates, Geisler, Patuzzi, & Johnstone, 1989).
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Speech and Hearing Sciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Glattke, Theodore J.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleThe creation of distortion products through the interaction of spontaneous otoacoustic emissions and externally generated tones.en_US
dc.creatorNorrix, Linda Weiland.en_US
dc.contributor.authorNorrix, Linda Weiland.en_US
dc.date.issued1995en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractA spontaneous otoacoustic emission (SOAE) and external tones (XTs) were used as primaries f₂ and f₁, respectively (frequency of f₂ > f₁) to create 2f₁-f₂ distortion products (DPOAEs). The DPOAEs primarily reflect active processes in the cochlea because low- to medium-level primaries less than 60 dB SPL were employed. DPOAE characteristics were determined and compared to what is known from the literature about DPOAEs created using two XTs. SOAE frequency and amplitude were also described. One hundred twenty-two women were screened for the presence of SOAEs to obtain 10 subjects for the study. XTs were presented to the ear at SOAE/f₁ ratios between 1.08 and 1.22. Sound pressure levels were incremented in 5 dB steps and extended from levels equal to the initial SOAE amplitudes to levels at which the SOAEs and DPOAEs disappeared into the noise floor. Amplitude and frequency of the SOAE, XT, and DPOAE were recorded by placing a low-noise microphone in the ear canal and extracted using Fast Fourier Transform analysis. Results indicated that the DPOAE amplitudes and SOAE suppression characteristics were variable across subjects. Despite the variability, the following trends were noted: (1) at larger frequency ratios, DPOAE generation and SOAE suppression were associated with greater XT levels; (2) DPOAE growth functions were characterized by slopes less than 1 dB/dB, a maximum, rollover and disappearance into the noise floor with increasing XT levels; (3) maximum amplitude DPOAEs were observed at frequencies approximately one-half octave lower than the SOAE; (4) DPOAE thresholds were associated with little SOAE suppression whereas the maximum DPOAEs were associated with a greater amount of SOAE suppression; (5) the most common SOAE frequency shift, in the presence of XT stimulation, was a shift to a higher frequency just prior to total SOAE suppression. Results are interpreted using an electrical circuit model (modified from Yates, 1990) and pictorial representations of the SOAE, XT, and DPOAE vibrational patterns on the basilar membrane (modified from Yates, Geisler, Patuzzi, & Johnstone, 1989).en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineSpeech and Hearing Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairGlattke, Theodore J.en_US
dc.contributor.committeememberBoliek, Carolen_US
dc.contributor.committeememberHosford-Dunn, Hollyen_US
dc.contributor.committeememberGreen, Kerryen_US
dc.contributor.committeememberSwisher, Lindaen_US
dc.identifier.proquest9531124en_US
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