The Hearing and Speech Research Laboratory at Smith-Kettlewell is investigating the role of audition in people with hearing/visual impairment. There are both scientific and practical reasons why a vision institute should study hearing. First, it is known that there are interactions between the two sensory modalities. Vision has an influence on the auditory perception of speech. Second, hearing is the primary information channel for those who have severe visual impairment, so it is important that we learn more about the auditory cues that blind and partially sighted individuals use for mobility and localizing the direction and distance of sounds. Finally, it is estimated that approximately 3 million Americans have impairment in both sensory modalities. Most of these individuals are over age 65. My research has focused on the investigation of three aspects of human communication: speech perception, binaural hearing, and sensory aids for the hearing impaired. Speech is the most important sound for humans since we are not only expected to hear it, but understand it.

There is an advantage to using both eyes and both ears. Binocularity enhances our depth perception and enlarges the size of the visual field. Binaurality allows us to localize sounds, to listen selectively to one signal among noisy competitors, and to squelch reverberation and background noise; it also enhances speech perception and the quality of sound. One of the most devastating aspects of the sensory deficit of hearing loss is the inability to process ordinary speech in the midst of background noise, and conventional binaural hearing aids do not provide a satisfactory solution to this crucial problem. There are still many unanswered questions about how the normal auditory system functions, and even more about the impaired system. In my laboratory, we intend to develop and evaluate a clinical battery of tests to predict who could benefit from binaural amplification with the new state-of-the-art wide dynamic range multichannel compression hearing aids. We are studying the nature and time course of the new hearing aid users' adjustment to this new type of amplification for sound localization and speech perception using behavioral measurements and functional magnetic resonance imaging (fMRI).

For more information, visit Helen Simon's lab web pages.

Collaborators: Al Lotze, Brian Brown. Arthur Jampolsky, Harry Levitt, E. William Yund, Robert Madory, Christina Roup, Yoram Bonneh, Joshua Miele.