Seminars in Hearing Research at Purdue

Students, post docs, and faculty with interests in all aspects of hearing meeting weekly to share laboratory research, clinical case studies, and theoretical perspectives. Topics include basic and translational research as well as clinical practice. Participants are welcome from all of Purdue University including Speech, Language, and Hearing Science (SLHS), Biology (BIO), Biomedical Engineering (BME), Mechanical Engineering (ME), and Electrical Engineering (EE). Seminars provide an ideal venue for students to present their work with a supportive audience, for investigators to find common interests for collaborative efforts, and for speakers from outside Purdue to share their work. This seminar is partially supported by the Association for Research in Otolaryngology.

2018-2019 Talks

Past Talks

LYLE 1150: 1030-1120am (link to schedule)

September 20, 2018

Brandon S Coventry, Ph.D. Candidate, Weldon School of Biomedical Engineering, Purdue Institute of Integrative Neuroscience, and Center for Implantable Devices, Purdue University

Optical deep brain stimulation of the central auditory pathway

Neurological and sensory neuroprostheses based on electrical stimulation have proven effective in restoring auditory percepts in cochlear and auditory brainstem implants as well as treatment of Parkinson’s disease and Tourette’s syndrome with deep brain stimulation (DBS). However, deficits in modern devices, such as current spillover and inability to selectively target local circuits, results in undesirable auditory percepts in sensory prostheses and undesirable side effects in central nervous system implants. Infrared neural stimulation (INS) is an optical technique which has been shown to selectively stimulate nerves and neurons using long wavelength (> 1450 nm) infrared light. INS is a promising stimulation modality because it does not require genetic modification of the target, allowing translation to human patients without additional genetic manipulations. Furthermore, previous studies in nerve have suggested that INS is more spatially specific than conventional electrical stimulation. Preliminary studies in the central nervous system have suggested INS can elicit responses in cortical structures. However the efficacy of INS in generating biophysical responses in thalamocortical networks is unexplored. Demonstration of effective thalamocortical recruitment would establish INS a potential stimulation therapeutic which could theoretically improve on cochlear and brainstem implant performance. In this study, Sprague-Dawley rats of both sexes were implanted with optrodes in the medial geniculate body (MGB) in the auditory thalamus and 16 channel microwire arrays in the primary auditory cortex (A1). After recovery, auditory and infrared stimuli were presented to awake, restrained animals. Auditory stimuli consisted of click trains at sound levels between 60 and 90 dB, random spectrum stimuli with spectral contrasts of 5, 10, and 15 dB, and amplitude modulated broadband noise. Infrared stimuli operated in quasi-continuous wave with singular pulses of 0-600 mW power with varying pulse widths between 5-100 ms duration. Initial results show that infrared stimulation of MGB gives rise to repeatable and short-latency action potentials and local field potentials in the auditory cortex. Furthermore, joint-peristimulus time historgram analysis suggests that INS acts in a spatially specific manner, recruiting only local circuits for activation. Finally, the use of INS for next generation cochlear implants and auditory brainstem/midbrain implants will be discussed.

September 13, 2018

Prof. Lisa L. Hunter, Ph.D., FAAA, Scientific Director of Research, Division of Audiology, Cincinatti Children's Hospital Medical Center​

High frequency hearing, otoacoustic emissions and speech-in-noise deficits due to aminoglycoside ototoxicity in cystic fibrosis

Aminoglycoside antibiotics are used world-wide to treat drug-resistant chronic lung infections. These lifesaving drugs unfortunately cause hearing loss due to ototoxicity, the effects of which progress from the base to the apex of the basilar membrane (inner ear). Therefore, in order to detect ototoxicity sooner, the higher frequency region is important to assess.  This presentation will discuss extended high-frequency hearing and transient-evoked otoacoustic emissions to chirps (TEOAEs) to detect ototoxicity in pediatric patients with cystic fibrosis (CF) treated with aminoglycosides, compared to age-matched untreated controls. TEOAEs were measured using chirp stimuli at frequencies from 0.7-14.7 kHz, along with audiometry and speech-in-noise thresholds on the BKB-SIN test. Hearing thresholds were significantly poorer in the CF group than the control group at all frequencies, but particularly from 8-16 kHz, with thresholds in the CF group ranging up to 80 dB HL. Speech-in-noise performance using the BKB-SIN test was significantly poorer for the CF group compared to controls and age norms. TEOAE signal to noise ratios were significantly poorer in the CF group with significant hearing loss in the 8-10 kHz frequency regions, compared to controls without hearing loss. These results show that newly-developed chirp TEOAE measures in the extended high-frequency range are effective in detection of cochlear impacts of ototoxicity. Poorer speech-in-noise function in the group treated with aminoglycosides provides additional physiologic evidence of cochlear, and possibly neural deficits.

September 6, 2018

Alexandra Mai, Audiology Graduate Student, Purdue University, presenting NIH T35 student research conducted at BoysTown National Research Hospital

Beliefs Held by Parents of Infants and Toddlers with Hearing Loss 

It is understood that the amount of time children wear their hearing devices and the amount of parent involvement is associated with language outcomes for children. However, device use and parent involvement are highly variable. Additionally, it is known that parents’ beliefs affect parenting actions and a child’s early cognitive development (Keels 2009). The Scale of Parental Involvement and Self-Efficacy- Revised (SPISE-R) queries parents’ beliefs, knowledge, confidence, and actions as well as their child’s device use to examine parental self-efficacy. This study focused on the beliefs section of the questionnaire. Each of the eight beliefs has a cut-off where responses past this point are considered concerning and additional counseling to the parent is recommended. The purpose of this study was to see what percent of parents held concerning beliefs, examine how children and family factors (i.e. parental education level, child’s current age, age at confirmation of the hearing loss, degree of hearing loss, and hearing device type) affected parent beliefs, and determine if a parent holding a concerning belief was associated with differences in their child’s device use or language development. This was done via an online survey made up of a demographic questionnaire, the SPISE-R, the Developmental Profile- 3 communication subscale (DP-3), and the Parenting Sense of Confidence self-efficacy subscale. Parents were also asked to submit their child’s most recent audiological results. Results indicate that a significant number of parents held concerning beliefs for all statements except two involving family and early interventionist impact. Additionally, parental education level, degree of hearing loss, age at confirmation, and current age of the child were each correlated with holding a concerning belief for one belief statement. Finally, only a concerning belief about if a child’s hearing device(s) helps him/her to communicate was associated with device use. No beliefs in the concerning range were associated with language development.

August 23, 2018

Josh Alexander (Alexander Lab)

Potential Mechanisms for Perception of Frequency-Lowered Speech   

About 25% of the more than 36 million Americans with hearing loss and about 40% of all hearing aid users have at least a severe hearing impairment.  These individuals have significant difficulty perceiving high-frequency speech information even with the assistance of conventional hearing aids.  Frequency lowering is a special hearing aid feature that is designed to help these individuals by moving the mid- to high-frequency parts of speech to lower-frequency regions where hearing is better.  This feature is offered in various forms by every major hearing aid manufacturer and it is the standard of care for children when conventional amplification fails to provide audibility of the full speech spectrum (American Academy of Audiology, 2013).  However, there is a lack of strong evidence about when and how this feature should be used in the clinic.  This stems from a critical knowledge gap concerning mechanisms important for the perception of frequency-lowered speech.  Continued existence of this gap contributes to the lack of reproducibility of findings in this research area, suboptimal patient outcomes, and ineffective interventions.   This talk will focus on research conducted by the Experimental Amplification Research (EAR) lab on the latest commercially available method of frequency lowering, adaptive nonlinear frequency compression.  This method provides unprecedented control over how sounds are remapped onto the residual capabilities of the impaired cochlea.  A systematic investigation of the perceptual effects of this method in normal-hearing listeners was conducted using a variety of speech stimuli that had been processed with 8-9 different frequency-lowering settings for each of three hearing loss conditions.  Auditory nerve model and acoustic analyses revealed that broadband temporal modulation accounted for 64-94% of the variance across each of the data sets.  In fact, the data also revealed that current clinical recommendations for selecting frequency-lowering settings might significantly undermine potential benefit from this feature.  A working hypothesis is that frequency-lowering methods and settings that preserve the greatest amount of temporal modulation from the original speech at the auditory periphery will yield the best outcomes for speech perception.  Finally, this talk will discuss how the results from normalhearing listeners compare favorably to predictions generated from auditory nerve simulations of various degrees of sensorineural hearing loss. 

Speech, Language, & Hearing Sciences, Lyles-Porter Hall, 715 Clinic Drive, West Lafayette, IN 47907-2122, PH: (765) 494-3789

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