Perceptual learning and sensorimotor adaptation with cochlear-implant simulated speech feedback

Cochlear implants (CIs) provide deaf individuals with access to auditory feedback from their own voice when speaking. This experiment investigated whether typical hearing participants can use CI simulated speech feedback for perceptual learning and sensorimotor control of speech. CI simulation was achieved via real-time noise vocoding, a technique that degrades the spectral detail in a speech signal in a manner similar to a CI. 32 participants took part in the experiment. First, participants were tested on their recognition of noise vocoded sentences before and after a training task; either perception training, during which participants listened to noise vocoded sentences while reading matching text; or production training, during which participants read aloud sentences whilst hearing their own voice noise-vocoded in real-time. Both perception and production training tasks resulted in significant improvements in recognition of noise vocoded sentences, with no effect of training type. Both groups then underwent a speech motor adaptation paradigm in which formants were perturbed in real-time noise vocoded speech auditory feedback. Speech motor adaptation however was not significant at the group level in response to the formant perturbations. This suggests that successful perceptual learning of degraded speech is not sufficient for successful sensorimotor learning with degraded auditory feedback.