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Purpose Cannabis is a widely used drug both medically and recreationally. The aim of this study was to determine if cannabis smoking is associated with changes in auditory function, as measured by behavioral hearing thresholds and/or... more
Purpose Cannabis is a widely used drug both medically and recreationally. The aim of this study was to determine if cannabis smoking is associated with changes in auditory function, as measured by behavioral hearing thresholds and/or distortion product otoacoustic emissions (DPOAEs). Method We investigated hearing thresholds and 2f 1 –f 2 DPOAEs in 20 cannabis smokers and 20 nonsmokers between 18 and 28 years old. Behavioral thresholds were obtained from 0.25 to 16 kHz. DPOAEs were measured using discrete tones between f 2 of 0.5 and 19.03 kHz using an f 2 /f 1 ratio of 1.22 and L 1 /L 2 = 65/55 dB SPL. Thresholds and DPOAE amplitudes were compared between groups using linear mixed-effects models with sex and frequency as predictors. Results Behavioral thresholds in smokers did not differ significantly between smokers and nonsmokers (all p s > .05). Although not significant, long-term smokers exhibited poorer thresholds than short-term smokers and nonsmokers. Smokers generally exhibited lower DPOAE amplitudes than nonsmokers, although the differences were not significant. Male smokers had significantly poorer DPOAE amplitudes than male nonsmokers in the low frequencies (f 2 ≤ 2 kHz; p = .0245). Conclusion Results indicate that smoking cannabis may negatively alter the function of outer hair cells in young men. This subtle cochleopathology is evident in the absence of measurable differences in behavioral hearing thresholds between cannabis smokers and nonsmokers.
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The impact of bilateral gain reduction on localization and speech perception in spatially-separated noise THE IMPACT OF BILATERAL GAIN REDUCTION ON LOCALIZATION AND SPEECH PERCEPTION IN SPATIALLY-SEPARATED NOISE Title and Department Date THE IMPACT OF BILATERAL GAIN REDUCTION ON LOCALIZATION AND ...more
Bilaterally independent (mismatched) hearing aids cannot replicate the natural timing and level cues between ears, and hence, may result in negative consequences for localization and speech perception in spatially-separated noise... more
Bilaterally independent (mismatched) hearing aids cannot replicate the natural timing and level cues between ears, and hence, may result in negative consequences for localization and speech perception in spatially-separated noise performance. Five gain reduction patterns were used to evaluate the impact of bilaterally mismatched gain reduction schemes on localization and speech perception performance in noise, compared to an unaltered bilaterally linear time-invariant amplification scheme (reference scheme), in which audibility was optimized. The bilaterally mismatched gain reduction schemes were later matched (synchronized) between ears to explore the possibility of restoring the deteriorated performance due to the mismatched schemes. Sound quality and listening-effort ratings among different gain reduction patterns were assessed, as well as the relationship between self-reported localization ability in daily life and measured localization performance in a laboratory setting. Twent...
Research Interests: Psychology, Audiology, Fluency disorders, Stuttering, Medicine, and 13 moreSpeech, Learning, Humans, Female, Male, Language Culture and Communication, Psychological Tests, Adult, Sensory Feedback, Communication sciences and disorders, Motor Skills, Psychology and Cognitive Sciences, and Medical and Health Sciences
Intermodulation distortion has been hypothesized as a mechanism contributing to the generation of short-latency (SL) components in the transient-evoked otoacoustic emission (TEOAE). Presumably, nonlinear interactions between the frequency... more
Intermodulation distortion has been hypothesized as a mechanism contributing to the generation of short-latency (SL) components in the transient-evoked otoacoustic emission (TEOAE). Presumably, nonlinear interactions between the frequency components within the evoking stimulus induce cochlear distortion products, which mix in the cochlea and ear canal with reflected energy from each stimulus-frequency's tonotopic place. The mixing of these different components is evidenced in the bandpass-filtered emission waveform as a series of different latency peaks. The current study tested the hypothesis that intermodulation distortion, induced within the spectral bandwidth of the evoking stimulus, is the primary mechanism through which the SL components are generated. The nonlinear-derived tone-burst-evoked OAE (TBOAEnl) was evoked using 2-kHz tone bursts with durations of 3, 6, 12, and 24 cycles. As tone burst duration doubled, the spectral bandwidth was halved. It was hypothesized that ...
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To model the contribution of implant material and insertion trauma on loss of acoustic hearing after cochlear implantation in an appropriate animal model. Sixty-five C57Bl/6J mice underwent unilateral implantation with implant grade... more
To model the contribution of implant material and insertion trauma on loss of acoustic hearing after cochlear implantation in an appropriate animal model. Sixty-five C57Bl/6J mice underwent unilateral implantation with implant grade materials: 2 implant grade silicones and a third uncoated platinum wire. A sham surgery group was included as a control. Serial auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAEs) were used to discern effects on hearing over 22 weeks. Histologic measurements of damage to the organ of Corti and spiral ganglion were correlated with degree of hearing loss and material type. Organ of Corti damage correlated with rate of hearing loss soon after implantation (0-2 weeks) but not subsequently (2-22 weeks). Organ of Corti damage did not depend on implant type and was present even in sham surgery subjects when hearing was severely damaged. Spiral ganglia appeared unaffected. There was no evidence of an inflammatory or toxic effect of the materials beyond the site of implant insertion. Hearing loss and cochlear damage appear to be related to insertion trauma, with minimal effect on delayed hearing loss caused by different materials. In the C57Bl/6J mouse model, the sensory epithelium appears to be the location of damage after cochlear implantation.
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This poster is available in pdf form on the Auditory Research Lab website:
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Purpose The aim of this study was to investigate the effects of preoral sensorimotor cues on anticipatory swallowing/eating-related mouth movements in older and younger adults. It was hypothesized that these cues are essential to timing... more
Purpose The aim of this study was to investigate the effects of preoral sensorimotor cues on anticipatory swallowing/eating-related mouth movements in older and younger adults. It was hypothesized that these cues are essential to timing anticipatory oral motor patterns, and these movements are delayed in older as compared with younger adults. Method Using a 2 × 2 repeated-measures design, eating-related lip, jaw, and hand movements were recorded from 24 healthy older (ages 70–85 years) and 24 healthy younger (ages 18–30 years) adults under 4 conditions: typical self-feeding, typical assisted feeding (proprioceptive loss), sensory-loss self-feeding (auditory and visual loss/degradation), and sensory-loss assisted feeding (loss/degradation of all cues). Results All participants demonstrated anticipatory mouth opening. The absence of proprioception delayed lip-lowering onset, and sensory loss more negatively affected offset. Given at least 1 preoral sensorimotor cue, older adults initi...
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To model the contribution of implant material and insertion trauma on loss of acoustic hearing after cochlear implantation in an appropriate animal model. Sixty-five C57Bl/6J mice underwent unilateral implantation with implant grade... more
To model the contribution of implant material and insertion trauma on loss of acoustic hearing after cochlear implantation in an appropriate animal model. Sixty-five C57Bl/6J mice underwent unilateral implantation with implant grade materials: 2 implant grade silicones and a third uncoated platinum wire. A sham surgery group was included as a control. Serial auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAEs) were used to discern effects on hearing over 22 weeks. Histologic measurements of damage to the organ of Corti and spiral ganglion were correlated with degree of hearing loss and material type. Organ of Corti damage correlated with rate of hearing loss soon after implantation (0-2 weeks) but not subsequently (2-22 weeks). Organ of Corti damage did not depend on implant type and was present even in sham surgery subjects when hearing was severely damaged. Spiral ganglia appeared unaffected. There was no evidence of an inflammatory or...
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One purported use of low-level laser therapy (LLLT) is to promote healing in damaged cells. The effects of LLLT on hearing loss and tinnitus have received some study, but results have been equivocal. The purpose of this study was to... more
One purported use of low-level laser therapy (LLLT) is to promote healing in damaged cells. The effects of LLLT on hearing loss and tinnitus have received some study, but results have been equivocal. The purpose of this study was to determine if LLLT improved hearing, speech understanding, and/or cochlear function in adults with hearing loss. Using a randomized, double-blind, placebo-controlled design, subjects were assigned to a treatment, placebo, or control group. The treatment group was given LLLT, which consisted of shining low-level lasers onto the outer ear, head, and neck. Each laser treatment lasted approximately five minutes. Three treatments were applied within the course of one week. A battery of auditory tests was administered immediately before the first treatment and immediately after the third treatment. The battery consisted of pure-tone audiometry, the Connected Speech Test, and transient-evoked otoacoustic emissions. Data were analyzed by comparing pre- and postte...
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provided invaluable technical assistance without which this work could not have been completed. Many thanks are owed to my family and friends. v ABSTRACT Nonlinear frequency compression is a signal processing technique used to increase... more
provided invaluable technical assistance without which this work could not have been completed. Many thanks are owed to my family and friends. v ABSTRACT Nonlinear frequency compression is a signal processing technique used to increase the audibility of high frequency speech sounds for hearing aid users with sloping, high frequency hearing loss. However, excessive compression ratios may reduce spectral contrast between sounds and negatively impact speech perception. This is of particular concern in infants and young children, who may not be able to provide feedback about frequency compression settings. This study explores use of an objective cortical auditory evoked potential that is sensitive to changes in spectral contrast, the auditory change complex (ACC), in the verification of frequency compression parameters. We recorded ACC responses in adult listeners to a spectral ripple contrast stimulus processed with a range of frequency compression ratios (1:1 to 4:1). Vowel identifica...
In the cochlea, the basilar membrane (BM) vibrates in response to sound. The BM separates the different frequency components of sound along its length. BM vibration is a combination of passive mechanics and an active “cochlear amplifier.”... more
In the cochlea, the basilar membrane (BM) vibrates in response to sound. The BM separates the different frequency components of sound along its length. BM vibration is a combination of passive mechanics and an active “cochlear amplifier.” The cochlear amplifier arises from the motion of cochlear outer hair cells, which change their length in response to specific frequencies. This boosts the amplitude of BM vibration, which improves hearing of soft sounds and frequency resolution. The Medial Olivocochlear Reflex (MOCR) is a feedback pathway in the brainstem which, in the presence of background noise, lessens the boost of the cochlear amplifier. MOCR can be indirectly measured using Otoacoustic Emissions (OAEs), which are soft sounds originating in the cochlea as a byproduct of cochlear amplifier activity. Past research suggests that the MOCR alters the magnitude and phase of OAEs and BM vibration. However, the apparent phase change may be a change in frequency. This would suggest tha...
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This study describes a time series-based method of middle ear muscle reflex (MEMR) detection using bilateral clicks. Although many methods can detect changes in the otoacoustic emissions evoking stimulus to monitor the MEMR, they do not... more
This study describes a time series-based method of middle ear muscle reflex (MEMR) detection using bilateral clicks. Although many methods can detect changes in the otoacoustic emissions evoking stimulus to monitor the MEMR, they do not discriminate between true MEMR-mediated vs artifactual changes in the stimulus. We measured MEMR in 20 young clinically normal hearing individuals using 1-s-long click trains presented at six levels (65 to 95 dB peak-to-peak sound pressure level in 6 dB steps). Changes in the stimulus levels over the 1 s period were well-approximated by two-term exponential functions. The magnitude of ear canal pressure changes due to MEMR increased monotonically as a function of click level but non-monotonically with frequency when separated into 1/3 octave wide bands between 1 and 3.2 kHz. MEMR thresholds estimated using this method were lower than that obtained from a clinical tympanometer in ∼94% of the participants. A time series-based method, along with statistical tests, may provide additional confidence in detecting the MEMR. MEMR effects were smallest at 2 kHz, between 1 and 3.2 kHz, which may provide avenues for minimizing the MEMR influence while measuring other responses (e.g., the medial olivocochlear reflex).
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The auditory efferent system, especially the medial olivocochlear reflex (MOCR), is implicated in both typical auditory processing and in auditory disorders in animal models. Despite the significant strides in both basic and translational... more
The auditory efferent system, especially the medial olivocochlear reflex (MOCR), is implicated in both typical auditory processing and in auditory disorders in animal models. Despite the significant strides in both basic and translational research on the MOCR, its clinical applicability remains under-utilized in humans due to the lack of a recommended clinical method. Conventional tests employ broadband noise in one ear while monitoring change in otoacoustic emissions (OAEs) in the other ear to index efferent activity. These methods, (1) can only assay the contralateral MOCR pathway and (2) are unable to extract the kinetics of the reflexes. We have developed a method that re-purposes the same OAE-evoking click-train to also concurrently elicit bilateral MOCR activity. Data from click-train presentations at 80 dB peSPL at 62.5 Hz in 13 young normal-hearing adults demonstrate the feasibility of our method. Mean MOCR magnitude (1.7 dB) and activation time-constant (0.2 s) are consiste...
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Functional outcomes of medial olivocochlear reflex (MOCR) activation, such as improved hearing in background noise and protection from noise damage, involve moderate to high sound levels. Previous noninvasive measurements of MOCR in... more
Functional outcomes of medial olivocochlear reflex (MOCR) activation, such as improved hearing in background noise and protection from noise damage, involve moderate to high sound levels. Previous noninvasive measurements of MOCR in humans focused primarily on otoacoustic emissions (OAEs) evoked at low sound levels. Interpreting MOCR effects on OAEs at higher levels is complicated by the possibility of the middle-ear muscle reflex and by components of OAEs arising from different locations along the length of the cochlear spiral. We overcame these issues by presenting click stimuli at a very slow rate and by time-frequency windowing the resulting click-evoked (CE)OAEs into short-latency (SL) and long-latency (LL) components. We characterized the effects of MOCR on CEOAE components using multiple measures to more comprehensively assess these effects throughout much of the dynamic range of hearing. These measures included CEOAE amplitude attenuation, equivalent input attenuation, phase...
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Purpose Cannabis is a widely used drug both medically and recreationally. The aim of this study was to determine if cannabis smoking is associated with changes in auditory function, as measured by behavioral hearing thresholds and/or... more
Purpose Cannabis is a widely used drug both medically and recreationally. The aim of this study was to determine if cannabis smoking is associated with changes in auditory function, as measured by behavioral hearing thresholds and/or distortion product otoacoustic emissions (DPOAEs). Method We investigated hearing thresholds and 2f 1 –f 2 DPOAEs in 20 cannabis smokers and 20 nonsmokers between 18 and 28 years old. Behavioral thresholds were obtained from 0.25 to 16 kHz. DPOAEs were measured using discrete tones between f 2 of 0.5 and 19.03 kHz using an f 2 /f 1 ratio of 1.22 and L 1 /L 2 = 65/55 dB SPL. Thresholds and DPOAE amplitudes were compared between groups using linear mixed-effects models with sex and frequency as predictors. Results Behavioral thresholds in smokers did not differ significantly between smokers and nonsmokers (all p s > .05). Although not significant, long-term smokers exhibited poorer thresholds than short-term smokers and nonsmokers. Smokers generally ex...
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Measurement of changes in transient-evoked otoacoustic emissions (TEOAEs) caused by activation of the medial olivocochlear reflex (MOCR) may have clinical applications, but the clinical utility is dependent in part on the amount of... more
Measurement of changes in transient-evoked otoacoustic emissions (TEOAEs) caused by activation of the medial olivocochlear reflex (MOCR) may have clinical applications, but the clinical utility is dependent in part on the amount of variability across repeated measurements. The purpose of this study was to investigate the within- and across-subject variability of these measurements in a research setting as a step toward determining the potential clinical feasibility of TEOAE-based MOCR measurements. In 24 normal-hearing young adults, TEOAEs were elicited with 35 dB SL clicks and the MOCR was activated by 35 dB SL broadband noise presented contralaterally. Across a 5-week span, changes in both TEOAE amplitude and phase evoked by MOCR activation (MOC shifts) were measured at four sessions, each consisting of four independent measurements. Efforts were undertaken to reduce the effect of potential confounds, including slow drifts in TEOAE amplitude across time, activation of the middle-e...
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Objective: To evaluate the impact of non-adaptive matched and mismatched gain reduction schemes on localization in spatially-separated noise. Design: Inspired by the function of commercial noise reduction algorithms, five... more
Objective: To evaluate the impact of non-adaptive matched and mismatched gain reduction schemes on localization in spatially-separated noise. Design: Inspired by the function of commercial noise reduction algorithms, five frequency-specific gain reduction filter schemes were created, three for a modulated babble-noise and two for an unmodulated speech-shaped noise. Applying these schemes as both matched and mismatched conditions across ears, localization of five everyday sounds in noise was measured in a virtual environment using insert earphones. The performance in the reference scheme (no gain reduction in either ear) was measured as well. Study sample: Twenty-four adult bilateral hearing-aid users were enrolled in this study. Results: One of the two mismatched gain reduction schemes for the unmodulated noise had a small but negative impact on localization compared to the reference scheme. For that scheme more high-frequency reduction was noted than for the other schemes. Matching...
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The presence of short-latency (SL), less compressive-growing components in bandpass-filtered transient-evoked otoacoustic emission (TEOAE) waveforms may implicate contributions from cochlear regions basal to the tonotopic place. Recent... more
The presence of short-latency (SL), less compressive-growing components in bandpass-filtered transient-evoked otoacoustic emission (TEOAE) waveforms may implicate contributions from cochlear regions basal to the tonotopic place. Recent empirical work suggests a region of SL generation between ∼1/5 and 1/10-octave basal to the TEOAE frequency's tonotopic place. However, this estimate may be biased to regions closer to the tonotopic place as the TEOAE extraction technique precluded measurement of components with latencies shorter than ∼5 ms. Using a variant of the non-linear, double-evoked extraction paradigm that permitted extraction of components with latencies as early as 1 ms, the current study empirically estimated the spatial-extent of the cochlear region contributing to 2 kHz SL TEOAE components. TEOAEs were evoked during simultaneous presentation of a suppressor stimulus, in order to suppress contributions to the TEOAE from different places along the cochlear partition. Th...
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Research Interests: Physics, Medicine, Humans, Female, Male, and 5 moreClinical Sciences, Adult, Cochlea, Neurosciences, and Acoustic Stimulation
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Formant dynamics in vowel nuclei contribute to vowel classification in English. This study examined listeners' ability to discriminate dynamic second formant transitions in synthetic high front vowels. Acoustic measurements were made... more
Formant dynamics in vowel nuclei contribute to vowel classification in English. This study examined listeners' ability to discriminate dynamic second formant transitions in synthetic high front vowels. Acoustic measurements were made from the nuclei (steady state and 20% and 80% of vowel duration) for the vowels /i,I,e,ε,æ/ spoken by a female in /bVd/ context. Three synthesis parameters were selected to
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Research Interests: Acoustics, Materials Science, Sound, Medicine, Multidisciplinary, and 4 moreHumans, Calibration, Pressure, and Ear canal
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The murine model has been used extensively to model and study human deafness. Technical difficulty in the surgical approach due to the small size of the tympanic bulla and a robust stapedial artery has limited its application for studies... more
The murine model has been used extensively to model and study human deafness. Technical difficulty in the surgical approach due to the small size of the tympanic bulla and a robust stapedial artery has limited its application for studies of cochlear implantation and electrical stimulation. We describe a minimally traumatic, stapedial artery-sparing approach to the round window that may be used to access the mouse cochlea for acute or chronic studies of implantation and stimulation. Animal model. Fifteen C57BL6J mice were used to validate this approach. Auditory brainstem response threshold and distortion product otoacoustic emissions were obtained preoperatively and 2 weeks postoperatively to determine hearing preservation results. The approach provided excellent exposure for round-window implantation. Substantial hearing was preserved in all animals with a mean postimplantation auditory brainstem response threshold increase of 27.8 dB. Otoacoustic emissions were lost in subjects with the largest threshold shifts. Residual hearing after cochlear implantation is a determinant of success both with standard cochlear implant electrodes and with electrodes designed to optimize hearing preservation. Here, we have preserved usable hearing after implantation of C57BL6J mice, an endogenous model of human presbycusia. The murine model may become a powerful tool to assay the effects of cochlear intervention in different genetic backgrounds.