Electric-Acoustic Stimulation of Hearing in Adults and Children

Third place award in category at The Denman Undergraduate Research ForumThe purpose of this study was to test a possible way of improving speech perception through a cochlear implant, especially for children. Although implants provide a signal that is speech-like, the quality of sound is much different from typical speech. Most deaf listeners have a little low-frequency residual hearing. The idea was explored that perhaps speech perception would be improved by amplifying any residual hearing, even if a small amount, and combining it with the electric signal received through an implant. Three hypotheses were tested. H1: Recognition would be better for a simulated implant signal combined with a low-pass acoustic signal than for the implant simulation alone. H2: Greater benefits would be observed for sentence materials than for isolated words because low-frequency signals provide information primarily about sentence structure. H3: Children would show greater effects than adults because they rely more on the kinds of structure available in the low frequencies. Participants were 20 7-years-olds and 20 adults, all with normal hearing. They identified individual words and sentences with two kinds of processed speech: (1) speech band-pass filtered between 250 and 8000 Hz, and then noise vocoded in four channels, which replicates the signal available through a cochlear implant; and (2) that signal combined with the original signal low-pass filtered below 250 Hz. The results revealed that both children and adults benefitted from the addition of low-frequency information to the vocoded speech for words and sentences. The effect of adding the low-frequency signal was larger for sentences than for individual words. Adults performed better than children in all conditions, but listeners in both groups showed equivalent benefit from the addition of the low-frequency signal. Thus, H1 and H2 were supported, but not H3. Combining acoustic hearing through a high-powered hearing aid with electric hearing through a cochlear implant might enhance speech perception for deaf listeners.College of Arts and Sciences Undergraduate Research ScholarshipSocial and Behavioral Sciences Undergraduate Research GrantNo embargoAcademic Major: Speech and Hearing Scienc