We study many aspects of hearing, ranging from how the ear processes sound to how the brain interprets the signals it receives from the ear. Most of our work involves behavioral (or psychoacoustic) studies using people with normal or impaired hearing. Here are some of the projects that people in our lab are currently working on:
Pitch, along with loudness and timbre, is one of the fundamental auditory percepts. It is crucial for our appreciation of music and plays a vital role is speech perception. Most importantly perhaps, differences in pitch are used by the auditory system to segregate sounds. Our work concentrates on the perception of multiple pitches in normal-hearing and hearing-impaired listeners. The aim is to uncover the neural basis of pitch perception, using behavioral techniques and, in collaboration with others, functional magnetic resonance imaging (fMRI) and magneto-encephalography (MEG).
Whiteford, K. L., and Oxenham, A. J. (2015). "Using individual differences to test the role of temporal and place cues in coding frequency modulation," Journal of the Acoustical Society of America 138, 3093-3104.
Graves, J. E., Micheyl, C., and Oxenham, A. J. (2014). "Expectations for melodic contours transcend pitch," Journal of Experimental Psychology: Human Perception and Performance 40, 2338-2347.
Allen, E. J., and Oxenham, A. J. (2014). "Symmetric interactions and interference between pitch and timbre," Journal of the Acoustical Society of America 135, 1371-1379.
Micheyl, C., Schrater, P. R., and Oxenham, A. J. (2013). "Auditory frequency and intensity discrimination explained using a cortical population rate code," PLoS Computational Biology 9, e1003336.
Speech Perception With Acoustic And Electric Hearing
Speech presented in isolation can be degraded and distorted in many ways and still remain highly intelligible. Our work concentrates on more critical situations, with the speech presented in various acoustic backgrounds, where the auditory system has to "work hard" render speech sounds intelligible.
Oxenham, A. J., and Kreft, H. A. (2014). "Speech perception in tones and noise via cochlear implants reveals influence of spectral resolution on temporal processing," Trends in Hearing 18, 1-14.
Ruggles, D. R., Freyman, R. L., and Oxenham, A. J. (2014). "Influence of musical training on understanding voiced and whispered speech in noise," PLoS One 9, e86980.
Gregan, M. J., Nelson, P. B., and Oxenham, A. J. (2013). "Behavioral measures of cochlear compression and temporal resolution as predictors of speech masking release in hearing-impaired listeners," Journal of the Acoustical Society of America 134, 2895-2912.
Neural and Perceptual Bases Of Auditory Scene Analysis
We effortlessly parse an incoming acoustic waveform into perceptual objects (such as words or notes) or streams (such as speech or melodies), but very little is known about the underlying neural processing beyond the level of the cochlea. This project aims to uncover neural correlates of auditory object and stream formation by combining behavioral (psychoacoustic) measures with measures of brain activation (using MEG and fMRI) in various acoustic situations where listeners hear one, two, or many auditory streams.
Brandewie, E. J., and Oxenham, A. J. (2015). "Retroactive streaming fails to improve concurrent vowel identification," PLoS One 10, e0140466.
Christiansen, S. K., and Oxenham, A. J. (2014). "Assessing the effects of auditory stream formation through comodulation masking release," Journal of the Acoustical Society of America 135, 3520-3529.
Ruggles, D. R., and Oxenham, A. J. (2014). "Perceptual asymmetry induced by the auditory continuity illusion," Journal of Experimental Psychology: Human Perception and Performance 40, 908-914.
Perceptual Measures and Consequences of Normal and Abnormal Cochlear Processing
PI: Magdalena Wojtczak
The inner ear, or cochlea, is the first stage of processing along the auditory pathways. It is where sound energy is transformed into neural spikes, which are transmitted along the auditory nerve to the brain. Most cases of hearing impairment involve some damage to the cochlea. This project has two main aims:
1. Use otoacoustic emissions (OAEs) and behavioral measures to measure the effects of top-down (efferent) activation on human cochlear mechanics. Understanding how cochlear mechanics are changed by dynamic efferent effects should lead to improved signal processing in situations where the cochlea (or efferent activation) is impaired.
2. Use psychoacoustic and speech measures to explore the effects of across-frequency differences in cochlear processing delays.
Beim, J. A., Elliott, M., Oxenham, A. J., and Wojtczak, M. (2015). "Stimulus frequency otoacoustic emissions provide no evidence for the role of efferents in the enhancement effect," Journal of the Association for Research in Otolaryngology 16, 613-629.
Wojtczak, M., Beim, J. A., and Oxenham, A. J. (2015). "Exploring the role of feedback-based auditory reflexes in forward masking by Schroeder-phase complexes," Journal of the Association for Research in Otolaryngology 16, 81-99.
Wojtczak, M., Beim, J. A., Micheyl, C., and Oxenham, A. J. (2013). "Perception of across-frequency asynchrony by listeners with cochlear hearing loss," Journal of the Association for Research in Otolaryngology 14, 573-589.
Hearing Loss and Cochlear-Implant Research
Clinical Psychoacoustics Laboratory
Some of our research is carried out in the Clinical Psychoacoustics Lab, founded by Professor Emeritus David Nelson, in the Department of Otolaryngology.
This lab conducts research specifically aimed at understanding and correcting impaired hearing, including:
Auditory Analysis and Sensorineural Hearing Loss: The ability to hear changes in sound intensity and frequency is investigated in hearing-impaired patients to find ways to improve their sound perception.
Cochlear-Implant Research: Electrical stimulation of the auditory nerve through cochlear implants is investigated to improve sound perception in deaf patients.
Wang, N., Kreft, H. A., and Oxenham, A. J. (2015). "Loudness context effects in normal-hearing listeners and cochlear-implant users," Journal of the Association for Research in Otolaryngology 16, 535-545.
Bierer, J. A., Bierer, S. M., Kreft, H. A., and Oxenham, A. J. (2015). "A fast method for measuring psychophysical thresholds across the cochlear implant array," Trends in Hearing 19, 1-12.
Kreft, H. A., Nelson, D. A., and Oxenham, A. J. (2013). "Modulation frequency discrimination with modulated and unmodulated interference in normal hearing and in cochlear-implant users," Journal of the Association for Research in Otolaryngology 14, 591-601.
Our research is funded primarily by the National Institute on Deafness and other Communication Disorders (NIDCD).