Multiple Routes to Perceptual Learning

A listener’s ability to utilize indexical information in the speech signal can enhance their performance on a variety of speech perception tasks. It is unclear, however, whether such information plays a similar role for spectrally reduced speech signals, such as those experienced by individuals with cochlear implants. The present study compared the effects of training on linguistic versus indexical tasks when adapting to cochlear implant simulations. Listening to sentences processed with an 8-channel sinewave vocoder, three groups of subjects were trained on a transcription task (Transcription), a talker identification task (Talker ID) or a gender identification task (Gender ID). Preto post-test comparisons demonstrated that training produced significant improvement for all groups. Moreover, subjects from the Talker ID and Transcription training groups performed similarly at post-test and generalization, and significantly better than the subjects from the Gender ID training group. These data suggest that training on an indexical task that requires high levels of attention can provide equivalent benefit to training on a linguistic task. When listeners selectively focus their attention on the extralinguistic information in the speech signal, they still extract linguistic information, the degree to which they do so, however, appears to be task dependent.