Information for coarticulation: Static signal properties or formant dynamics?

Area of Science:

• Speech perception
• Auditory processing
• Psychoacoustics

Background:

• Perception of speech segments is influenced by surrounding sounds, a phenomenon known as compensation for coarticulation.
• Two main theories exist: one posits low-level auditory contrast effects from static signal properties, while the other suggests dynamic attunement to acoustic effects of gestural overlap.

Purpose of the Study:

• To investigate whether static signal properties or dynamic formant relationships in speech precursors drive perceptual shifts in compensation for coarticulation.
• To differentiate between auditory contrast and gestural attunement accounts of coarticulation.

Main Methods:

• Utilized sinewave speech precursors in two experiments to manipulate acoustic properties.
• Experiment 1 confirmed that sinewave precursors induce perceptual shifts.
• Experiment 2 temporally reversed F1 and F2 in precursors, preserving static F3 but disrupting dynamic formant relationships.

Main Results:

• Sinewave speech precursors significantly shifted perception of following speech segments.
• Temporally reversing F1 and F2 in precursors, while maintaining static F3, resulted in significantly smaller perceptual shifts.
• These effects were limited to a narrow portion of the speech continuum.

Conclusions:

• Dynamic formant relationships, not static signal properties like F3 frequency, provide the crucial information for compensation for coarticulation.
• Findings support the theory that listeners attune to dynamic gestural information for speech perception.