Much of the hospital's success in identifying and treating children with hearing loss is the result of the rapid transfer of research findings from laboratories to clinic and bedside.

Areas of Research - Clinical and Behavioral Studies of Human Communication - Auditory Perception Laboratory

Overview

Research in this laboratory explores how more central auditory processes affect the ability of adult and child listeners to perceive sounds that are degraded, unpredictable or otherwise non-optimal. The emphasis is on what auditory cues and listening strategies help listeners, particularly children and adults with cochlear implants, process target sounds in the presence of competing background sounds. Past research in our laboratory has demonstrated that even adults with normal hearing can have great difficulty separating a simple, unchanging target tone from competing background tones when the pitches of the background tones change unpredictably. Further, there are often large differences in performance across individuals, with poor performers persisting in non-optimal listening strategies despite extensive training.

Formerly part of the Psychoacoustics Laboratory, the Auditory Perception Laboratory uses several different approaches to examine detection, discrimination, and pattern recognition of sounds in isolation or in various backgrounds. Subjects are children and adults with cochlear implants as well as children and adults with normal hearing who listen to cochlear-implant simulations or unprocessed sounds for comparison.  Much progress has been made for speech perception in quiet environments for cochlear-implant users, however, music perception and speech perception in noisy environments typically remain poor. Further, normal hearing children appear to differ from adults in their ability to segregate competing sounds.  Our research goals are to better understand the cues and strategies used for sound-source segregation for cochlear-implant users, to understand how development and training might influence performance, and to account for the large individual differences in performance often observed in degraded listening environments.   This may lead to new approaches for measuring and improving both speech perception in noise and music perception with cochlear implants.

Staff

The laboratory is directed by Donna L. Neff, Ph.D.   The lab has strong collaborative ties with the Cochlear Implant Laboratory directed by Dr. Michelle Hughes, the Psychoacoustics Laboratory directed by Dr. Walt Jesteadt, and the Hearing Aid Laboratory directed by Dr. Patricia Stelmachowicz.

Summary of Research Program :

For Clinicians and Scientists

This program focuses on the role of auditory selection attention and other related cognitive processes in the perception of more complex non-speech sounds.  Past studies have used informational-masking tasks and sample-discrimination tasks to test the ability of normal-hearing adults to separate tonal targets from competing background sounds. Statistical properties of the stimuli were manipulated and perceptual weights calculated from trial-by-trial correlates of the stimuli to each listener’s responses to determine specific aspects of the stimuli that influenced performance. One important finding was that performance varied widely across individuals for these tasks even for highly trained adults with normal hearing. In addition to other factors (e.g. peripheral neural survival), it is probable that aspects of auditory selective attention revealed by these tasks may contribute significantly to the large individual differences in performance observed with CI users. Further, both music perception and speech perception in noise are currently very difficult for CI users and may be improved by a better understanding of their non-speech pattern perception. Finally, important aspects of auditory selective attention and pattern perception are likely to change with development.

Research in the Auditory Perception Laboratory therefore pursues several related aspects of selective attention and pattern recognition, with the goal of better understanding and predicting differences in performance for adults and children with cochlear implants. Normal hearing adults and children provide important comparison data. Current studies focus on pitch-based cues to pattern processing and address the following questions: 1) Can normal hearing adults and adult cochlear-implant users use dissimilarity in pattern versus background sounds to recognize simple non-speech auditory patterns? 2) Can normal hearing young children and children with cochlear implants use dissimilarity in pattern versus background to recognize simple non-speech auditory patterns, and are their pattern-recognition abilities similar to adults? 3) Can performance on specific measures of informational masking or pattern recognition be used to better understand and predict the large individual differences in speech-perception performance with cochlear implants? The goals are to develop better tools for assessing performance for cochlear-implant users and guide strategies for stimulus processing or habilitation that will improve both speech-in-noise and music perception abilities for cochlear-implant users.

Families

This research program examines the ability of adults and young children with normal hearing and with cochlear implants to hear target sounds in difficult listening conditions, such as when the target sounds are poor in quality or there are distracting background sounds. In these situations, hearing ability depends not just on the ear (for normal hearing) or the cochlear-implant device and implant-processing strategy, but also on higher-level processing by the brain.  These higher-level processes include attention, memory, listening strategies, and pattern perception. Our studies use behavioral measures, that is, listeners must indicate what they hear by giving a response, such as pushing a button or touching a screen to select an answer.  Previous work in this laboratory has used tasks in which the properties of target sounds and background sounds were varied to examine how listeners separate “relevant” from “irrelevant” sounds, especially when pitch information is varied.  We found that certain properties of sounds influenced performance more than others, and even adults with normal hearing showed large differences in their ability to do these tasks. Research in our labs and other labs has also shown that the hearing abilities change with age from infancy to adulthood.

Our current studies measure the ability of adults and children with normal hearing and with cochlear implants to identify simple tonal patterns presented in quiet or embedded in various background sounds.  The sounds used test how various cues, particularly pitch-based cues, help separate patterns from backgrounds, and whether these cues change in different listening situations or with age (children vs. adults). Although rapid progress has been made for speech perception in quiet for cochlear-implant users, speech perception in noise and music perception remain very difficult. The goal of this research program is to better understand and predict differences in the use of pitch-based cues for separating targets from backgrounds for children and adults with cochlear implants, with normal hearing listeners providing important comparison information.  It is hoped that these studies will result in the development of better tools for measuring and improving the ability of cochlear-implant users to understand speech in noisy backgrounds and enjoy music.

Professional Resources: none

Specific Areas of Research:

1. Using detection and discrimination tasks with uncertain stimuli to better understand auditory selective attention in normal hearing children and adults.
2. Using non-speech pattern recognition tasks to better understand music perception abilities and limitations for adult and children with cochlear implants.
3. Determining the degree to which children and adults with normal hearing and with cochlear implants can use various sound properties to separate target sounds from competing background sounds.
4. Determining the contribution of central auditory processes in the large individual differences observed in cochlear-implant performance to develop better predictive measures of real-world performance