Research in the Cochlear Implant Laboratory is aimed at investigating the relationship between subjective and objective measures obtained with electrical stimulation of the human auditory system. Subjective (or behavioral) measures require active participation on the part of the research subject. Examples of subjective measures include listening to sounds and making judgments about certain aspects of the sound (e.g., loudness or pitch) or listening to speech presented in different conditions and repeating words or sentences. Objective measures do not require active participation from the subject. The objective measures made in our laboratory consist of measurements made from the auditory pathways in response to electrical stimulation from the subject’s cochlear implant. The goal of this research is to determine whether certain objective measures can be used to predict certain behavioral measures. We hope to use this information to find better ways to program cochlear implant speech processors for children and adults.
The laboratory consists of three rooms: (1) a large sound-attenuating booth equipped with a sound field system, recliner, television, VCR/DVD player, impedance bridge, and touch-screen monitor; (2) an adjacent control room equipped with an audiometer, a networked color printer, two laptops, one PC, and cochlear implant speech processor interfaces for controlling psychophysical and physiologic experiments; (3) general lab space equipped with a pediatric table and chairs, toy chest, desk space and computer for a research assistant, file storage, and lab meeting space.
The laboratory is directed by Michelle L. Hughes, Ph.D., CCC-A. Lab staff are Jenny Goehring, Au.D., CCC-A, Jacquelyn Baudhuin, Au.D., CCC-A, Kirsten Euscher, B.A., and Donna Neff, Ph.D. Three staff members are certified audiologists.
Summary of Research Program
For Clinicians and Scientists
The overall goal of this research project is to better understand the relation between physiological measures of temporal and spatial interaction in cochlear implants (CIs) and performance on psychophysical and speech-perception tasks. Speech-processor program parameters such as stimulation rate, number of electrodes, or stimulus timing (i.e., simultaneous or sequential stimulation) can be manipulated to some extent to reduce interaction in either the temporal or spatial domain. However, it is not clear what the relative contributions of temporal and spatial interaction are to speech-perception ability and how these effects vary across individual CI users. It is possible that interaction affects CI recipients in different ways based on differences in peripheral physiology. Further, differences in peripheral physiology may account for differences in performance as a function of programming choices across individual CI recipients. It is anticipated that research findings from this project may translate into objective methods that can be used to choose specific CI speech-processor programming parameters to maximize performance on an individual basis. This research project consists of three specific aims. The first aim is to evaluate the extent to which physiological measures of auditory-nerve temporal response properties relate to sychophysical measures of temporal integration and performance with different rates of stimulation. These studies will evaluate temporal response properties of the auditory nerve, temporal integration ability, and speech-perception performance with different rates of stimulation. We hypothesize that neural measures such as refractory-recovery and stochastic independence will aid in predicting an optimal stimulation rate for individual CI users. The second aim is to examine the extent to which physiological measures of spatial selectivity are related to pitch ranking and electrode discrimination for intermediate (or virtual) channels. These studies will evaluate the relation between physiological measures of spatial selectivity using actual and virtual channels versus pitch ranking and electrode discrimination tasks. We hypothesize that measures of auditory-nerve spatial selectivity will aid in predicting whether intermediate pitches can be perceived for individual CI users. These measures may lead to objective ways to determine whether an individual subject may benefit from a strategy that employs expanded spectral representation through intermediate or virtual channels. The third aim is to examine the relative effects of physiological and psychophysical channel interaction for simultaneous and sequential stimulation. These studies will evaluate the relative contribution of each type of interaction to determine whether the potential benefits of increased stimulation rate outweigh potential disadvantages of electrical field interaction with simultaneous stimulation. We hypothesize that physiological measures may aid in predicting whether better performance is achieved with a fully sequential strategy versus a partially simultaneous strategy.
For cochlear implant recipients
Click here for more information on our current studies.
Bournique JL, Hughes ML, Baudhuin JL & Goehring JL (2013). Effect of ECAP-based choice of stimulation rate on speech-perception performance. Ear and Hearing, in press, doi: 10.1097/AUD.0b013e3182760729.
Goehring JL, Hughes ML, Baudhuin JL, & Lusk RP (2013). How well do cochlear implant intraoperative impedance measures predict postoperative electrode function? Otology & Neurotology, 34, 239-244.
Glassman EK & Hughes ML (2013). Determining electrically evoked compound action potential thresholds: A comparison of computer versus human analysis methods. Ear and Hearing, 34(1), 96-109.
Goehring JL, Hughes ML, & Baudhuin, JL (2012). Evaluating the feasibility of using remote technology for cochlear implants. The Volta Review, 112(3), 255-265.
Goehring JL, Hughes ML, Baudhuin JL, Valente DL, McCreery RW, Diaz GR, Sanford T, & Harpster R. (2012). The effect of technology and testing environment on speech perception using telehealth with cochlear implant recipients. Journal of Speech, Language, and Hearing Research, 55(5), 1373-1386.
Hughes ML, Goehring JL, Baudhuin JL, Diaz GR, Sanford T, Harpster R, & Valente DL (2012). Use of telehealth for research and clinical measures in cochlear implant recipients: A validation study. Journal of Speech, Language, and Hearing Research, 55, 1112-1127.
Hughes ML, Castioni EE, Goehring JL, & Baudhuin JL (2012). Temporal response properties of the auditory nerve: Data from human cochlear-implant recipients. Hearing Research, 285, 46-57.
Hughes ML (2012). Receiving and maintaining a cochlear implant: What Nurse Life Care Planners need to know. Journal of Nurse Life Care Planning, 12(2), 618-630.
Wiley S, Meinzen-Derr J, Grether S, Choo DI, Hughes ML (2012). Longitudinal functional performance among children with cochlear implants and disabilities: A prospective study using the Pediatric Evaluation of Disability Inventory. International Journal of Pediatric Otorhinolaryngology, 76, 693-697.
Hughes ML & Goulson AM (2011). Electrically evoked compound action potential measures for virtual channels versus physical electrodes. Ear and Hearing, 32, 323-330.
Hughes ML & Stille LJ (2010). Effect of stimulus and recording parameters on spatial spread of excitation and masking patterns obtained with the electrically evoked compound action potential in cochlear implants. Ear and Hearing, 31 (5), 679-692.
Saoji AA, Litvak LM & Hughes ML (2009). Excitation patterns of simultaneous and sequential dual electrode stimulation in cochlear implant recipients. Ear and Hearing, 30 (5), 559-567.
Hughes ML & Stille LJ (2009). Psychophysical and physiological measures of electrical-field interaction in cochlear implants. Journal of the Acoustical Society of America, 125 (1), 247-260.
Hughes ML (2008). A re-evaluation of the relation between physiological channel interaction and electrode pitch ranking in cochlear implants. Journal of the Acoustical Society of America, 124 (5), 2711-2714.
Hughes ML & Stille LJ. (2008). Psychophysical versus physiological spatial forward masking and the relation to speech perception in cochlear implants. Ear and Hearing, 29 (3), 435-452.