Julie Honaker, PhD
Gaze Stabilization Testing for Predicting Fall Risk
Reliable clinical assessment methods to identify falling risk are needed for appropriate referral and outcomes following intervention for risk of falling programs. Gaze Stabilization testing (GST) is a new clinical test for evaluating impairments in perceiving objects accurately during head movements. The use of this test to determine if an individual may be at risk of falling has not been explored in the literature. The aim of this study will be to determine whether Gaze Stabilization testing differs in patients who have experience falls in the recent past versus not and to identify a cut-point of GST^ that maximizes sensitivity and specificity for identifying patients at risk for falls. A secondary aim will be to compare GST versus the Dynamic Gait Index (DGI) for identifying patients at risk for falls. An equal number of patients with and without a history of falls will be included in a Receiver Operating Characteristic (ROC) analysis to assess whether GST can identify patients at risk for falls. Additionally, areas under the ROC curves for GST and DGI will be compared to assess which test is better for discriminating between patients at risk for falls versus not. |
Patti Johnstone, PhD
Sound Source Identification Ability and Minimum Audible Angle Thresholds in Children with Unilateral Sensorineural Hearing Loss: The Effect of Amplification
Little is known about how unilateral hearing loss affects spatial hearing in children and virtually nothing is known about how a hearing aid in the impaired ear might affect performance. Accurate sound localization (sound source identification) is a complex perceptual process that requires the integration of interaural disparities in intensity and time. A child who has been deprived of interaural cues, due to a unilateral hearing loss, might be expected to have difficulty localizing sounds. The proposed study will investigate the effect of unilateral sensorineural hearing loss on sound source identification abilities and minimum audible angle (MAA) thresholds in children. In addition, it will study the effect of using a hearing aid in the impaired ear on sound source identification and MAA in the horizontal plane in children with unilateral sensorineural hearing loss. Performance will also be compared to age-matched controls with normal hearing.
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Angela Yarnell Bonino, MS
Children’s Speech Perception in Noise: Ability to Use a Carrier Phrase to Separate the Target from the Background
Children perform more poorly on speech perception measures in noise than adults. One potential explanation for children’s increased susceptibility to noise is that they have difficulty perceptually segregating the target speech from the competing background noise. Providing cures for the perceptual segregation of a signal from the background can improve children’s thresholds for detecting a tone of informational masking paradigms which use a competing background of multiple frequency components. A carrier phrase may provide a similar type of cue during a speech perception task by allowing the listener to form a coherent auditory stream with the additional temporal and spectral information. We have recently shown that using a carrier phrase improves children’s performance for Phonetically-Balance Kindergarten (PBK) words in multi-talker babble (Bonino & Leibold, 2007). The purpose of the proposed research is to determine if the benefit of using the carrier phrase in a competing background is because it assists children in perceptual segregation by forming a coherent auditory stream for the signal. |
Kristal Mills, BS
NADPH Oxidase and Auditory Function
The vestibular system consists of two sets of organs—otolith organs and semi-circular canals. The otolith organs sense linear acceleration due to otoconia, calcium carbonate crystals that sit atop the gelatinous layer overlying these organs. Otoconia provide a mass load that bends the stereocilia of the hair cells, which ultimately activates vestibular neurons. Numerous genes have been identified that affect otoconia. Some of these genes, such as Nox3 and Noxo1, are also expressed in the cochlea. Nox3 and Noxo1 play a role in the formation of a NADPH oxidase complex thought to be critical in vestibular function. The NOX family of NADPH oxidase is reactive oxygen species (ROS) generating enzyme. ROS plays a rold in hearing loss—noise induced, drug induced, and age related. A functional role for Nox3 and Noxo1 in the auditory system is disputed or unknown. The purpose of the proposed research is to assess auditory function in Nox3 and Noxo1 mouse straings. To do this, we will measure auditory brainstem response and otoacoustic emissions in homozygotes and heterozygotes from 2 to 12 months of age. Vestibular evokes potentials will be used to test otolithic function. Data available from C5&BL/6J mice will be used as background strain controls.
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Erica Williams, MS
The Effects of Quinine-Induced Hearing Loss on Speech and Psychophysical Tasks
The significant variability in speech recognition abilities for listeners with at least a mild sensorineural hearing loss (SNHL) cannot be fully explained by reduced audibility. Thus, many have focused on supratherhold tasks such as frequency selectivity and temporal resolution. Confounds such as age-related changes in frequency selectivity, temporal resolution and speech recognition in addition to multiple and variable sites of hearing loss may have affected these results. Quinine causes a temporary hearing loss due to its action on the OHCs. Because most hearing loss affects at least the OHCs, quinine provides a model to study the effects of hearing loss due to OHC damage on speech recognition, and the relationship between speech recognition and suprathresold measures of frequency selectivity and temporal resolution. It also provides a model to study the effects of hearing loss on compression. Previous results are mixed as to whether hearing loss reduces the magnitude of compression or reduces the range of levels over to address this issue. The results of the proposed experiments will provide important insight into the role of OHCs in hearing and the effect of hearing loss. |
Kathleen Mettel
Complex Sound Representation in the Rat Ventral Auditory Field
Current research is focusing on how sound is processed throughout the various levels of the auditory system. The auditory cortex is one of the higher levels in the hierarchy of auditory processing. Here, a primary field (AI) and multiple “belt fields” have been discovered using anatomical and physiological approaches. Many of these studies and overall knowledge of these belt fields warrants further study. The overall goal of this area of research is to understand how different fields represent sounds, from simple pure tones to complex sounds such as noise and even speech. There are multiple techniques to study the functional organization of the auditory cortex. One of these techniques, microelectrode mapping, allows the experimenter to determine how individual neurons respond to different features of acoustic stimuli. This involves placing microelectrodes at many locations in the cortex and directly recording the response of neurons. These recording sites together form a “map” that shows how neurons respond within and across different cortical fields.
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Christopher Spankovich, AuD, MPH
Noise Exposure: Acute Insults and Delayed Neurodegenerative Outcomes
Although SGC death takes many months to appear, there are clear-cut signs of acute neuropathy within the cochlear epithelium in the hours and days following exposure. To examine this degeneration, two primary methods of investigation will be utilized. First, confocal microscopy (Aim 1) will be performed to track degeneration over post-exposure time as it progresses from synapse, to peripheral axon, to cell body. Progressive terminal degeneration at the first neurochemical synapse will likely have significant functional consequences for stimulus coding and information transfer; this model proves an unusual opportunity to access these events in ears with preserved outer and inner hair cells and good threshold sensitivity. In Aim 2, we will incorporate physiological characterization of these degenerative events, correlating them in time and cochlear location with the pathology. Measurement of threshold and suprathreshold response properties via cochlear DPOAEs and auditory neural CAPs and ABRs will be compared with measures of single-fiber activity from auditory nerve, work already underway by another student in the lab. Together, these measurements will provide insight into the functional state of the remaining synapses. |
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Kristi Buckley, MS
Plasticity, Speech Perception & Cochlear Implants
The amplitude of the evoked response to visual motion recorded over the right temporal lobe is compared to speech perception ability in individuals who wear a cochlear implant. A negative relationship between the amplitude of visual-evoked activity in the right temporal lobe and speech perception ability was found in individuals with pre-lingual deafness, but not in individuals with post-lingual deafness. |
Marc Brennan, MS
Effect of Expansion on Consonant Recognition
Expansion is used to reduce low-level background sounds, but may also make soft speech less audible (Plyler et al 1007 JSLHR 50:1). The precise audibility effects have not been examined. Reduced audibility might be mediated by the expansion kneepoint. This study measured consonant recognition at different expansion kneepoints for subjects with sensorineural hearing loss. Audibility was calculated using real-ear speech recordings. Results indicated reduced audibility and consonant recognition with a high kneepoint. |
Christine Alexander
Effects of Reverberation on Speech Recognition in Bimodal Cochlear Implants Patients
Reverberation, which is present in many environments, has strong negative effects on speech recognition. Binaural listening, however, lessens the effects of reverberation. As cochlear implant candidacy criteria broaden, an increased number of implant recipients use a hearing aid in the non-implanted ear. The purpose of the present study is to evaluate the effects of bimodal (implant plus hearing aid) listening on speech recognition in reverberant environments using multi-speaker simulation of diffuse noise fields. |
Kimberly Miller, BA
Improving the Selection of Release Time
A prevailing assumption is that cognition declines with age. Research suggests that speech intelligibility improves with fast- and slow-acting compression for younger and older listeners, respectively. We assessed the effect of age, hearing sensitivity, S/B ratio and release time on cognitive capacity. Findings revealed that selecting release time based on capacity, more so than age, provides greater validity of the listener’s ability to process the spectro-temporal properties of the incoming signal. |
Rosalinda Baca
Language Growth Trajectories in Children with Hearing Loss
Hierarchical Linear Modeling was used to describe the expressive language developmental trajectories of 244 children with hearing loss. The rate of language growth was higher for children with early entry into intervention, milder degrees of hearing loss, and born after the establishment of Universal Newborn Hearing Screening (UNHS). A meaningful gap in language status at 3 years old was observed in spite of early intervention and UNHS for greater degrees of hearing loss. |
Dane Bowers, MA
Cortically Mediated Release from Inhibition in the Cochlea
Cortical influence on the efferent olivocochlear bundle system was examined by measuring the effects of attention on contralateral suppression (CS) of click-evoked otoacoustic emissions in 15 normal-hearing listeners. CS was greatest in the non-attending condition and decreased significantly when attending to the click or broad-band-noise suppressor. Results suggest that heightened attention to either the ipsilateral, evoking stimulus or the contralateral suppressor causes a top-down, cortically mediated release from inhibition at the level of the cochlea. |
Susanna Love Callaway
Prescriptive Fitting of OTC Hearing Aids
Gain, output, and other electroacoustic characteristics of 11 OTC hearing devices in two price ranges, $100 and $100-$500, were examined for three common audiometric configurations using the NAL-R prescriptive formula. Results showed that all low-range devices were inadequate in meeting the needs of hearing-impaired individuals in regard to both gain and output, as well as other electroacoustic characteristics. Mid-range hearing devices are arguably of good quality and represent a feasible solution for the cost-conscious consumer. |
Kristy Lowery, MA
A Comparison of Video Versus Conventional VRA in Infants
Response patterns to video and conventional visual reinforcement audiometry (VVRA and CVRA, respectively) were investigated in fourteen 7- to 16-month-old infants using a repeated measures design. Each infant was tested with VVRA and CVRA over two sessions. Hit rate, false positives rate, test sensitivity, and reinforcement benefit for each condition were calculated. Results showed no difference between the two reinforcement methods, suggesting that VVRA can be used effectively in infants 7-16 months of age. |
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