Speakers correct their speech and stay on-target while talking by detecting even small deviations in their auditory feedback. Access to the acoustic details in auditory feedback crucially depends on intact hearing and self-perception systems, which can be degraded by lack of language experience, hearing impairment, or, in the case of cochlear implants, by the implant itself. These degraded auditory representations may compromise the speech production system, contributing to the loss of intelligibility seen in these populations. The suite of experiments proposed here tests how speakers detect deviations in their own speech under two atypical speaking conditions: speaking a foreign language and speaking with cochlear implants. In second lan- guage learning, a lack of experience with the foreign language results in an underdeveloped second-language perception system, which interferes with production of native-like speech. Without a strong acoustic representa- tion of the speech target for comparison, the perception system is not able to evaluate speech output for errors. In this experiment, established neuroimaging (magnetoencephalography) and behavioral methods will be used to assess how people speaking French as a second language use their auditory feedback to assess their pro- ductions. In people speaking their native language, deviation from an acoustic target is correlated with changes in acoustic trajectories as well as activity in auditory cortex. These measures will be compared with an of?ine self-perceptual measure of acoustic sensitivity to determine how speakers' error-detection differs between a ?rst and second language. In people with cochlear implants, the processor collapses spectral distinctions in the speech input, so that these speakers do not have access to all of the rich acoustic information available in the speech signal. In parallel with second language learners, this signal degradation may prevent comparison between the speech output and speech target, possibly diminishing the ability to correct nascent errors. In this experiment, recorded productions of CI users' speech will be altered and presented back to them in a discrimination task. The experiment tests how CI users perceive their own speech and determines whether the degraded speech signal provides enough information to allow for error-detection in running speech. The experiments proposed here seek to understand how auditory feedback affects error-detection when part of the speech production-feedback loop receives a degraded signal, and the methods will provide the candidate with the training required to apply linguistic theories of speech production to biomedicine. A better understanding of how error-detection changes when access to high-?delity auditory feedback is diminished will provide new avenues for improved treatments in disorders that affect speech communication.
We listen to our own voices while we are talking to make sure that we say what we intended to say, and that we speak in a way that is understandable to others. This project investigates how two populations, second-language learners and people with cochlear implants, are able to detect errors in their speech, given that they may not hear their own speech the way native speakers or typically-developing people do. Understanding differences in how speakers hear themselves and how such differences may affect their speech can inform interventions to help people to speak better.
