Although audition may appear to be the dominant sensory modality in speech production, the capacity for intelligible speech following severe hearing loss suggests that other sensory information - for example, somatosensory feedback - may also contribute to the achievement of speech targets. The aim of this thesis is to explore the role of somatosensory feedback in speech produced by healthy adults. / The first study aimed at providing a test of whether somatosensory feedback plays a role in speech production beyond the language acquisition period in early childhood. In order to achieve this goal, we designed a pattern of forces that affects jaw movements during speech production, but at the same time has no measurable acoustic effect. We found that subjects compensated for such a distortion in speech movement trajectories, even though it had no impact on the sounds. In contrast, no adaptation was observed in matched non-speech jaw movements, indicating that this was not an inevitable consequence of exposing the orofacial apparatus to this pattern of forces. This is the first demonstration that somatosensory information on its own drives the achievement of articulator positions in speech. / In study one, it was observed that subjects only adapted to the loads in the opening phase of the jaw movement. In order to elucidate this somewhat unexpected finding, we carried out experiments in which we manipulated the linguistic content of the training utterance. We found that subjects compensated for the perturbations only in portions of the movement that contained a vowel-to-vowel transition. It was suggested that the required kinematic precision during a transition between two vocal tract shapes associated with vowels is higher than during transitions between a consonant and a vowel. It also points to the speech-like nature of the observed adaptation. / The third study aimed at investigating the extent to which speech motor learning generalizes across acoustic contexts. We trained subjects to produce utterances while exposed to a velocity dependent force field. After learning, the subjects were tested with new utterances, matched on dynamics to the ones used in training. Note that even if the acoustic contents of the test and the training utterances were different, the loads had a similar effect on both speech movements. We showed that learning did not transfer to the test utterances; therefore adaptation was restricted to the specific training context. These results point to the specificity of speech motor learning.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.103014 |
| Date | January 2006 |
| Creators | Tremblay, Stéphanie. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Psychology.) |
| Rights | © Stéphanie Tremblay, 2006 |
| Relation | alephsysno: 002600219, proquestno: AAINR32248, Theses scanned by UMI/ProQuest. |
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