Current Research Projects

Perception of environmental sounds and speech in patients with cochlear implants
(Valeriy Shafiro)

Limited research has investigated cochlear implant (CI) patients' ability to perceive environmental sounds. In this study, environmental sound perception is assessed with a large-item test composed of 40 sound sources, each represented by four different tokens. The relationship between speech and environmental sound perception and the role of working memory and basic auditory abilities was examined based on patient performance on a battery of speech tests (HINT, CNC, and individual consonant and vowel tests), tests of basic auditory abilities (audiometric thresholds, gap detection, temporal pattern and temporal order tests), and a backward digit recall test. The results will demonstrate CI patients' ability to perceive environmental sounds, indicate the strength of association between speech and environmental sound perception, and the extent to which basic auditory abilities may be involved in mediating this association.

Effects of training on the identification of spectrally impoverished environmental sounds
(Valeriy Shafiro)

Listeners' ability to identify the sources of environmental sounds suffers considerably when sounds' spectral resolution is decreased. Spectral resolution needed for the identification of a large number of common environmental sounds requires a greater number of frequency channels than can be provided by any available cochlear implant. The lack of sufficient spectral resolution limits cochlear implant listeners' ability to know what is happening in their environment (what objects and events are making sound), and decreases their awareness of the environment. This research project is designed to test the hypothesis that identification of spectrally impoverished environmental sounds can be improved through training. It is further designed to determine whether training effects obtained with specific sounds can generalize to other sounds, and compare performance of cochlear implant users to normal-hearing listeners tested with acoustic simulations.


Perceptual processing of simultaneously occurring sounds
(Valeriy Shafiro & Brian Gygi)

In most cases, human auditory perception takes place in an environment where multiple independently produced sounds are competing for our attention. Successful performance on a number of real life tasks often requires attending to several simultaneous sound streams in order to find the one containing relevant information. Existing auditory perception tests, however, have only marginally addressed listeners' ability to simultaneously perceive information from multiple sound streams. Thus, the goal of this project is to determine whether listener ability to detect a change in a sound stream changes as a function of the number of sound streams present, and existing expectations of which stream will contain a change.


The role of native phonology in listening and reading errors of nonnative English speakers
(Valeriy Shafiro & Anatoliy Kharkhurin)

Languages of the world differ in their sound structure. The phonology of the native language can affect listeners' perception of the sounds of nonnative language. This project is designed (1) to examine which vowels of American English pose perceptual difficulties for native speakers of Russian at varying levels of English fluency, (2) to test the hypothesis that English word recognition errors can be partially accounted for by systematic vowel confusion patterns obtained in listening tests, and (3) examine the role of language specific letter-to-sound conversion rules on the amount of phonologically based errors.

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