Increased speech contrast induced by sensorimotor adaptation to a nonuniform auditory perturbation

Area of Science:

• Speech motor control
• Auditory feedback processing
• Sensorimotor adaptation

Background:

• Sensorimotor adaptation allows speakers to adjust speech in response to auditory feedback perturbations.
• The impact of this adaptation on communication effectiveness, particularly vowel contrast, is not well understood.
• Reduced vowel contrast is linked to intelligibility deficits in neurogenic speech disorders.

Purpose of the Study:

• To investigate if human speakers can adapt to a complex, nonuniform auditory feedback perturbation designed to reduce vowel distinctiveness.
• To determine if this adaptation can lead to increased vowel contrast, a factor relevant to intelligibility.

Main Methods:

• Twenty-five participants were exposed to a "vowel centralization" perturbation, shifting formant frequencies towards the vowel space center.
• The perturbation systematically altered acoustic properties of vowels, making them less distinct.
• Speech production was analyzed during and after the feedback perturbation.

Main Results:

• Speakers successfully adapted to the vowel centralization perturbation.
• Participants increased vowel space area and vowel contrast to counteract the feedback shift.
• The enhanced vowel contrast persisted after the perturbation was removed.

Conclusions:

• Sensorimotor adaptation can be effectively utilized to increase vowel contrast in speech.
• Complex, nonuniform alterations in auditory feedback can drive adaptive changes relevant to intelligible communication.
• This study provides evidence for the ecological relevance of speech motor learning in sensorimotor adaptation.