Lukas Suveg, Au.D.
Project Assistant, Binaural Hearing and Speech Laboratory
Waisman Center, University of Wisconsin-Madison
Effects of Peripheral Asymmetry on Speech Understanding in Simulations of SSD-CI Hearing
Patients with single-sided deafness (SSD) have the greatest interaural asymmetry – one ear has clinically normal acoustic hearing while the other has no usable hearing. Cochlear implant (CI)s have been used increasingly to manage SSD, restoring access to sound in the previously unusable auditory pathway. Although CI recipients with SSD (i.e., “SSD-CI”) can hear through both ears, the ability to integrate acoustic and electric stimulation from the typical and implanted ears, respectively, is variable. This variability is hypothesized to be reflected in the ability of SSD-CI users to fuse speech information arriving at the two ears simultaneously, and to encode speech information presented to the two ears using an inter-ear switching, or alternating pattern. Previous work with normal hearing listeners suggests that participants employ different listening strategies to understand the signal depending on the rate of switching. In this study, we simulate various aspects of CI processing among normal hearing listeners using vocoders to approximate the effect of current spread across electrical channels on peripheral encoding. Our initial data suggest that listening to unilaterally vocoded speech, which introduces a qualitative difference across ears, induces processing difficulty that results in an inability to maintain attention-switching at an earlier switching rate than it does when ears are symmetrical.
Funding: This work was supported by NIH-NIDCD grant R01DC003083 to Ruth Y. Litovsky and in part by a core grant from the NIH-NICHD (U54 HD090256) to the Waisman Center.