Abstract:

Despite advances in implant technology, cochlear implant (CI) users demonstrate a wide range in the ability to perceive speech in the absence of visual or contextual cues. Some progress has been made recently in the ability to explain perceptual performance with a CI. A quantitative, psychophysically based model of vowel perception by CI users of the SPEAK processing strategy generated confusion matrices that were remarkably similar to actual data [M. A. Svirsky and T. A. Meyer, Assoc. Res. Otolaryngol. Abs. 20, 59 (1997)]. The three dimensions of the parameter space are the centers of gravity of stimulation in the cochlea in response to the first three vowel formants. The free parameter of the model is the subject's ability to scale pitch percepts associated with different electrodes. Although this single-parameter model was not successful in predicting consonant confusions, when the model was expanded to incorporate psychophysical estimates of gap detection and high- versus low-frequency intensity difference discrimination, the model successfully predicted performance on a medial consonant test [Meyer et al., Conf. Implant. Aud. Prosthes. Abs. (1997)]. Relations between predicted and obtained performance on selected psychophysical tests will be discussed. [Work supported by NIH.]