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Effects of Knowledge of Task on Control of Oral-Nasal Balance in Speech
Varsha Srinivas1, Tim Bressmann2
1Department of Speech Language Pathology, University of Toronto, Toronto, Ontario, Canada.
Introduction:
Previous research has shown that altering the nasal signal level auditory feedback changed the control of oral-nasal balance in normal speakers. The present study investigated whether knowledge of the task and the instruction not to compensate would change the participants' response to the manipulation.
Methods:
Twenty participants (10 females) in 2 groups continuously repeated a sentence while their nasal signal level was increased or decreased and fed back to them via headphones, so the speakers heard themselves as more or less nasal, respectively. After the first recording session, participants were debriefed about the true nature of the experiment. They were instructed not to compensate in the second recording session. The outcome measures were the percentage changes of nasalance scores from the first baseline.
Results:
Statistical analysis using a repeated measures analysis of variance showed an effect of the nasal signal level, F(5,80) = 2.51, p = 0.049, and a nasal signal level by knowledge of task interaction effect, F(5,80) = 3.25, p = 0.019. Post hoc tests showed that the maximum nasal signal level auditory feedback resulted in a significant decrease of nasality from the initial baseline.
Conclusion:
Despite knowledge of the task, speakers were unable to resist compensating. As found in previous research, there was a numerically higher compensation response at the maximum than at the minimum nasal signal level auditory feedback condition.
