Timing interference to speech in altered listening conditions.

Area of Science:

• Speech Production and Control
• Auditory Neuroscience
• Human Motor Control

Background:

• Auditory feedback is crucial for regulating speech production.
• Disruptions in auditory feedback can lead to altered speech performance.
• A theoretical framework suggests speech timing relies on a timekeeper influenced by input relationships.

Purpose of the Study:

• To test a theory explaining speech disruption from altered auditory feedback.
• To investigate how synchronous versus asynchronous auditory feedback affects speech timing.
• To differentiate the impact of altered auditory feedback on speech timekeeping versus motor processes.

Main Methods:

• Subjects repeated a syllable at a fixed rate.
• Auditory feedback was manipulated using delayed auditory feedback (DAF) and frequency-shifted feedback (FSF).
• Timing variance was decomposed into timekeeper variance (Cv) and motor process variance (Mv).

Main Results:

• Delayed auditory feedback (DAF) significantly increased timekeeper variance (Cv) compared to no altered feedback or frequency-shifted feedback (FSF).
• Synchronous auditory alterations not requiring a decision (e.g., amplitude changes without response) did not affect Cv.
• Making a duration decision about altered auditory feedback increased Cv, particularly at longer repetition periods.

Conclusions:

• The timekeeping process in speech control is differentially affected by synchronous and asynchronous auditory inputs.
• Asynchronous auditory feedback, such as DAF, primarily disrupts the timekeeper mechanism.
• Synchronous auditory alterations that do not necessitate a cognitive response have minimal impact on speech timekeeping.