David S Velenovsky

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Courses

Scholarly Contributions

Chapters

• Velenovsky, D. S. (2007). Suppression of Otoacoustic Emissions. In Otoacoustic Emissions, Clinical Applications, 3rd Edition.
• Velenovsky, D. S. (2002). Contralateral and Bilateral Suppression of Otoacoustic Emissions. In Otoacoustic Emissions, Clinical Applications, 2nd Edition.

Journals/Publications

• Norrix, L. W., Thein, J., & Velenovsky, D. S. (2019). The effect of Kalman-weighted averaging and artifact rejection on residual noise during auditory brainstem response testing. American Journal of Audiology.
• Dean, J., & Velenovsky, D. S. (2018). Crossing Borders: The Importance of What You Leave Behind. The Hearing Journal.
• Norrix, L. W., & Velenovsky, D. S. (2018). Clinicians' guide to obtaining a valid auditory brainstem response to determine hearing status: Signal, noise, and cross-checks. American Journal of Audiology.
• Dean, J., & Velenovsky, D. S. (2017). Arizona Sonora Borders (ARSOBO) Hearing Health Program: A Cross Border Project for Inclusion. Perspectives of the ASHA Special Interest Groups, 2.
• Norrix, L. W., & Velenovsky, D. S. (2017). Unraveling the Mystery of ABR Corrections: The Need for Universal Standards.. Journal of the American Academy of Audiology, 28, 950-960.
• Velenovsky, D. S. (2015). Electronystagmography and Videonystagmography (ENG/VNG). Ear and hearing, 36(2), e61.
• Norrix, L. W., & Velenovsky, D. S. (2014). Auditory neuropathy spectrum disorder: a review. Journal of speech, language, and hearing research : JSLHR, 57(4), 1564-76.
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  Auditory neuropathy spectrum disorder, or ANSD, can be a confusing diagnosis to physicians, clinicians, those diagnosed, and parents of children diagnosed with the condition. The purpose of this review is to provide the reader with an understanding of the disorder, the limitations in current tools to determine site(s) of lesion, and management techniques.
• Bergevin, C., Dong, W., Carney, L., Velenovsky, D. S., Bonine, K. E., & Jarchow, J. L. (2013). Comparative auditory biomechanics probed by otoacoustic emissions. Proceedings of Meetings on Acoustics, 19.
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  Abstract: Since Kemp's discovery in 1978, otoacoustic emissions (OAEs) have provided valuable scientific and clinical tools for the study of the ear. For example, OAEs can provide objective measures of sensitivity and selectivity over the frequency range of 'active' hearing. Given the universality of OAEs across the kingdom Animalia, comparative studies can reveal how various morphological factors affect pe-ripheral auditory transduction and thereby what information is encoded for higher level cognition. Motivated by the complexity of cochlear mechanics and the many unknowns that currently exist, the present study de-scribes OAEs stemming from two non-mammalian groups whose auditory periphery is relatively simpler than that of mammals: several lizard genera (Heloderma, Tiliqua, Agama, and Tupinambis) that exhibit significant relative differences in tectorial membrane structure, and a highly vocal bird species (Melopsittacus undulatus). By utilizing recent improvements in OAE measurement and analysis strategies combined with quantitative anatomical measures (e.g., number of hair cells), these data shed new light upon emission generation mechanisms and how such tie back to a given species' ability to encode ecologically relevant sounds. Furthermore, these data serve to inform theoretical models of auditory biophysics by clarifying what roles various morphological features do (or do not) play. © 2013 Acoustical Society of America.
• Velenovsky, D., Norrix, L. W., Burgan, B., Ramirez, N., & Velenovsky, D. S. (2013). Interaural multiple frequency tympanometry measures: clinical utility for unilateral conductive hearing loss. Journal of the American Academy of Audiology, 24(3).
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  Tympanometry is a routine clinical measurement of the acoustic immittance of the ear as a function of ear canal air pressure. The 226 Hz tympanogram can provide clinical evidence for conditions such as a tympanic membrane perforation, Eustachian tube dysfunction, middle ear fluid, and ossicular discontinuity. Multiple frequency tympanometry using a range of probe tone frequencies from low to high has been shown to be more sensitive than a single probe tone tympanogram in distinguishing between mass- and stiffness-related middle ear pathologies (Colletti, 1975; Funasaka et al, 1984; Van Camp et al, 1986).
• Bergevin, C., Fulcher, A., Richmond, S., Velenovsky, D., & Lee, J. (2012). Interrelationships between spontaneous and low-level stimulus-frequency otoacoustic emissions in humans. Hearing Research, 285(1-2), 20-28.
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  PMID: 22509533;Abstract: It has been proposed that OAEs be classified not on the basis of the stimuli used to evoke them, but on the mechanisms that produce them (Shera and Guinan, 1999). One branch of this taxonomy focuses on a coherent reflection model and explicitly describes interrelationships between spontaneous emissions (SOAEs) and stimulus-frequency emissions (SFOAEs). The present study empirically examines SOAEs and SFOAEs from individual ears within the context of model predictions, using a low stimulus level (20 dB SPL) to evoke SFOAEs. Emissions were recorded from ears of normal-hearing young adults, both with and without prominent SOAE activity. When spontaneous activity was observed, SFOAEs demonstrated a localized increase about the SOAE peaks. The converse was not necessarily true though, i.e., robust SFOAEs could be measured where no SOAE peaks were observed. There was no significant difference in SFOAE phase-gradient delays between those with and without observable SOAE activity. However, delays were larger for a 20 dB SPL stimulus level than those previously reported for 40 dB SPL. The total amount of SFOAE phase accumulation occurring between adjacent SOAE peaks tended to cluster about an integral number of cycles. Overall, the present data appear congruous with predictions stemming from the coherent reflection model and support the notion that such comparisons ideally are made with emissions evoked using relatively lower stimulus levels. © 2012.
• Bergevin, C., Velenovsky, D. S., & Bonine, K. E. (2011). Coupled, active oscillators and lizard otoacoustic emissions. AIP Conference Proceedings, 1403, 453-458.
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  Abstract: The present study empirically explores the relationship between spontaneous otoacoustic emissions (SOAEs) and stimulus-frequency emissions (SFOAEs) in lizards, an ideal group for such research given their relatively simple inner ear (e.g., lack of basilar membrane traveling waves), diverse morphology across species/families (e.g., tectorial membrane structure) and robust emissions. In a nutshell, our results indicate that SFOAEs evoked using low-level tones are intimately related to underlying SOAE activity, and appear to represent the entrained response of active oscillators closely tuned to the probe frequency. The data described here indicate several essential features that are desirable to capture in theoretical models for auditory transduction in lizards, and potentially represent generic properties at work in many different classes of "active" ears. © 2011 American Institute of Physics.
• Bergevin, C., Velenovsky, D. S., & Bonine, K. E. (2010). Tectorial membrane morphological variation: effects upon stimulus frequency otoacoustic emissions. Biophysical journal, 99(4), 1064-72.
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  The tectorial membrane (TM) is widely believed to play an important role in determining the ear's ability to detect and resolve incoming acoustic information. While it is still unclear precisely what that role is, the TM has been hypothesized to help overcome viscous forces and thereby sharpen mechanical tuning of the sensory cells. Lizards present a unique opportunity to further study the role of the TM given the diverse inner-ear morphological differences across species. Furthermore, stimulus-frequency otoacoustic emissions (SFOAEs), sounds emitted by the ear in response to a tone, noninvasively probe the frequency selectivity of the ear. We report estimates of auditory tuning derived from SFOAEs for 12 different species of lizards with widely varying TM morphology. Despite gross anatomical differences across the species examined herein, low-level SFOAEs were readily measurable in all ears tested, even in non-TM species whose basilar papilla contained as few as 50-60 hair cells. Our measurements generally support theoretical predictions: longer delays/sharper tuning features are found in species with a TM relative to those without. However, SFOAEs from at least one non-TM species (Anolis) with long delays suggest there are likely additional micromechanical factors at play that can directly affect tuning. Additionally, in the one species examined with a continuous TM (Aspidoscelis) where cell-to-cell coupling is presumably relatively stronger, delays were intermediate. This observation appears consistent with recent reports that suggest the TM may play a more complex macromechanical role in the mammalian cochlea via longitudinal energy distribution (and thereby affect tuning). Although significant differences exist between reptilian and mammalian auditory biophysics, understanding lizard OAE generation mechanisms yields significant insight into fundamental principles at work in all vertebrate ears.
• McMullen, N. T., Velenovsky, D. S., & Holmes, M. G. (2005). Auditory thalamic organization: cellular slabs, dendritic arbors and tectothalamic axons underlying the frequency map. Neuroscience, 136(3), 927-43.
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  A model of auditory thalamic organization is presented incorporating cellular laminae, oriented dendritic arbors and tectothalamic axons as a basis for the tonotopic map at this level of the central auditory system. The heart of this model is the laminar organization of neuronal somata in the ventral division of the medial geniculate body (MGV) of the rabbit, visible in routine Nissl stains. Microelectrode studies have demonstrated a step-wise ascending progression of best frequencies perpendicular to the cell layers. The dendritic arbors of MGV neurons are aligned parallel to the cellular laminae and dendritic tree width along the frequency axis corresponds closely with the frequency steps seen in microelectrode studies. In the laminated subdivision, tectothalamic axons terminate in the form of bands closely aligned with the laminae and dendritic arbors of thalamic relay neurons. The bands of tectothalamic axons extend in the anterior-posterior (A-P) plane forming a dorsal-ventral series of stacked frequency slabs. In the pars ovoidea region, the homologous spiraling of somata, dendritic fields and tectothalamic axons appear to represent a low-frequency area in this species. At least two types of tectothalamic terminals were found within the bands: large boutons frequently arranged in a glomerular pattern and smaller boutons arising from fine caliber axons. We propose that the rabbit is an ideal model to investigate the structural-functional basis of functional maps in the mammalian auditory forebrain.
• Sinex, D. G., Hongzhe, L. i., & Velenovsky, D. S. (2005). Prevalence of stereotypical responses to mistuned complex tones in the inferior colliculus. Journal of Neurophysiology, 94(5), 3523-3537.
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  PMID: 16079190;PMCID: PMC2533264;Abstract: The human auditory system has an exceptional ability to separate competing sounds, but the neural mechanisms that underlie this ability are not understood. Responses of inferior colliculus (IC) neurons to "mistuned" complex tones were measured to investigate possible neural mechanisms for spectral segregation. A mistuned tone is a harmonic complex tone in which the frequency of one component has been changed; that component may be heard as a separate sound source, suggesting that the mistuned tone engages the same mechanisms that contribute to the segregation of natural sounds. In this study, the harmonic tone consisted of eight harmonics of 250 Hz; in the mistuned tone, the frequency of the fourth harmonic was increased by 12% (120 Hz). The mistuned tone elicited a stereotypical discharge pattern, consisting of peaks separated by about 8 ms and a response envelope modulated with a period of 100 ms, which bore little resemblance to the discharge pattern elicited by the harmonic tone or to the stimulus waveform. Similar discharge patterns were elicited from many neurons with a range of characteristic frequencies, especially from neurons that exhibited short-latency sustained responses to pure tones. In contrast, transient and long-latency neurons usually did not exhibit the stereotypical discharge pattern. The discharge pattern was generally stable when the stimulus level or component phase was varied; the major effect of these manipulations was to shift the phase of the response envelope. Simulation of IC responses with a computational model suggested that off-frequency inhibition could produce discharge patterns with these characteristics. Copyright © 2005 The American Physiological Society.
• Cetas, J. S., Price, R. O., Crowe, J., Velenovsky, D. S., & McMullen, N. T. (2003). Dendritic orientation and laminar architecture in the rabbit auditory thalamus. Journal of Comparative Neurology, 458(3), 307-317.
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  PMID: 12619083;Abstract: A laminar organization composed of the dendritic fields of principal neurons and afferent axonal arbors has been proposed as the anatomical substrate for the frequency map at several levels of the mammalian central auditory system, including the inferior colliculus and medial geniculate body (MGB). In contrast to the auditory thalamus in most mammals, the ventral division of the rabbit medial geniculate body (MGV) has cellular laminae visible in routine Nissl stains, allowing a direct comparison of the laminar organization with the dendritic architecture and frequency organization. In total 30 presumptive relay neurons in the MGV were labeled with the juxtacellular recording method, and their dendritic arbors were fully reconstructed from serial sections with the aid of a computer microscope. The spatial organization of MGV dendritic fields was analyzed using the dendritic prism, dendritic stick, and fan-in projection methods. Quantitative spatial analyses revealed that, for MGV neurons in the central pars lateralis subdivision, the major axis of the dendritic fields (∼29° relative to the horizontal plane) was closely aligned with that of the Nissl laminae (∼25°). Both were oriented orthogonally to the tonotopic axis. In contrast, cells in the pars ovoidea had their major axis of orientation parallel to the anteroposterior axis of the brain. Although a bitufted dendritic field was the norm, it was not uncommon for MGV neurons to have pronounced spatial asymmetries in their dendritic fields. A model is presented that incorporates cellular laminae and oriented dendritic growth to form frequency-related slabs within the MGV. © 2003 Wiley-Liss, Inc.
• Velenovsky, D. S., Cetas, J. S., Price, R. O., Sinex, D. G., & McMullen, N. T. (2003). Functional subregions in primary auditory cortex defined by thalamocortical terminal arbors: an electrophysiological and anterograde labeling study. The Journal of neuroscience : the official journal of the Society for Neuroscience, 23(1), 308-16.
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  Several functional maps have been described in primary auditory cortex, including those related to frequency, tuning, latency, binaurality, and intensity. Many of these maps are arranged in a discontinuous or patchy manner. Similarly, thalamocortical projections arising from the ventral division of the medial geniculate body to the primary auditory cortex are also patchy. We used anterograde labeling and electrophysiological methods to examine the relationship between thalamocortical patches and auditory cortical maps. Biotinylated dextran-amine was deposited into physiologically characterized sites in the ventral division of the medial geniculate body of New Zealand white rabbits. Approximately 7 d later, the animal was again anesthetized and the ipsilateral auditory cortex was mapped with tungsten microelectrodes. Multi-unit physiological data were obtained for the following characteristics: best frequency (BF), binaurality, response type, latency, sharpness of tuning, and threshold. Immunocytochemical methods were used to reveal the injection site in the ventral division of the medial geniculate body as well as the anterogradely labeled thalamocortical afferents in the auditory cortex. In 86% of the cases (12 of 14), entry into a thalamocortical patch was associated with a marked change in physiological responses. A consistent BF and binaural class were usually observed within a patch. The patches appear to innervate distinct functional regions coding frequency and binaurality. A model is presented showing how patchy thalamocortical projections participate in the formation of tonotopic and binaural maps in primary auditory cortex.
• Cetas, J. S., Price, R. O., Velenovsky, D. S., Crowe, J. J., Sinex, D. G., & McMullen, N. T. (2002). Cell types and response properties of neurons in the ventral division of the medial geniculate body of the rabbit. The Journal of comparative neurology, 445(1), 78-96.
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  Although there is evidence for multiple classes of thalamic relay neurons in the auditory thalamus, correlative anatomical and physiological studies are lacking. We have used the juxtacellular labeling technique, in conjunction with Nissl, Golgi, and immunocytochemical methods, to study the morphology and response properties of cells in the ventral division of the medial geniculate body of the rabbit. Single units in the ventral division of the medial geniculate body (MGV) were characterized extracellularly with monaural and binaural tone and noise bursts (100- to 250-msec duration). Characterized units were filled with biocytin and visualized with an antibody enhanced diaminobenzidine reaction. A total of 31 neurons were physiologically characterized and labeled with the juxtacellular technique. Labeled neurons were fully reconstructed from serial sections by using a computer microscope system. Three subregions of the rabbit MGV were identified, each characterized by differences in Nissl architecture, calcium-binding protein expression, and by the dendritic orientation of tufted relay neurons. In general, the dendritic fields of relay neurons were closely aligned with the cellular laminae. Qualitative and quantitative analyses revealed two types of presumptive relay neurons within the MGV. Type I cells had thick dendrites with a greater total volume and morphologically diverse appendages compared with the Type II cells whose dendrites were thin with a moderate number of small spines. Both classes were acoustically responsive and exhibited a variety of response patterns, including onset, offset, and sustained responses. In terms of binaural characteristics, most (ca. 53%) labeled neurons were of the EE type, with the remaining cells classified as EO (27%) or EI (20%) response types. Two types of presumptive interneurons were also seen: bipolar neurons with large dendritic fields and a small neurogliaform variety. Cell types and dendritic orientation within the MGV are discussed in terms of the physiological organization of the rabbit auditory thalamus.
• Velenovsky, D. S., & Glattke, T. J. (2002). The effect of noise bandwidth on the contralateral suppression of transient evoked otoacoustic emissions. Hearing Research, 164(1-2), 39-48.
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  PMID: 11950523;Abstract: The purpose of this study was to determine whether the bandwidth or loudness of a contralateral stimulus is the most important factor in evoking suppression of transient evoked otoacoustic emissions (TEOAEs). TEOAEs were measured in both ears of 10 women in quiet and in the presence of one of three contralateral noise bands; narrow band (NB), wide band (WB) and equalized (EQ), all centered at 2000 Hz. The NB (100 Hz bandwidth) and WB (2200 Hz bandwidth) noises were presented at 60 dB SPL. The SPL of the EQ (100 Hz bandwidth) noise was adjusted such that it was equal in loudness to the WB noise as determined using a psychoacoustic procedure. Only the WB noise was associated with a significant reduction of TEOAE levels. It is believed that this effect occurred because the WB noise has greater effective energy representation across frequency on the basilar membrane as it may receive more gain from the action of the cochlear amplifier. Results of the present study indicate that noise bandwidth is the most important factor in the contralateral suppression of TEOAEs. Copyright © 2002 Elsevier Science B.V.
• Cetas, J. S., Price, R. O., Velenovsky, D. S., Sinex, D. G., & McMullen, N. T. (2001). Frequency organization and cellular lamination in the medial geniculate body of the rabbit. Hearing Research, 155(1-2), 113-123.
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  PMID: 11335081;Abstract: Cellular laminae within the tonotopically organized ventral division of the medial geniculate body (MGV) of the cat have been proposed as the anatomical substrate for physiologically defined isofrequency contours. In most species, the laminae are not visible with routine Nissl stains, but are defined by the dendritic fields of principal cells and the terminal arbors of afferents arising from the inferior colliculus. In the present study, we have used the rabbit to directly examine the relationship between the laminar and tonotopic organization of the MGV. Best frequency maps of the MGV in anesthetized adult New Zealand white rabbits were generated from cluster responses recorded at 30-100 μm intervals to randomly presented tone bursts. Parallel vertical penetrations, roughly perpendicular to the laminae, revealed a low-to-high frequency gradient within the MGV. Non-laminated regions of the ventral division, generally found at the rostral or caudal poles, did not demonstrate a systematic frequency gradient. In contrast to a predicted smooth gradient, best frequencies shifted in discrete steps across the axis of the laminae. A similar step-wise frequency gradient has been shown in the central nucleus of the inferior colliculus of the cat. It is proposed that the central laminated core of the MGV represents an efficient architecture for creating narrow frequency filters involved in fine spectral analysis. Copyright © 2001 Elsevier Science B.V.

Poster Presentations

• Thein, J., Norrix, L. W., Vasey, J., & Velenovsky, D. S. (2018, March). Residual noise using Intelligent Hearing and Vivosonic Integrity ABR systems. American Auditory Society. Scottsdale, AZ.
• Denny, N., Velenovsky, D. S., & Dean, J. (2017, March). Validation of a novel hearing aid fitting guide for humanitarian audiology. American Auditory Society Annual Spring Meeting. Scottsdale, AZ.