Physiologic stages of vocal reaction time

Area of Science:

• Speech Physiology
• Auditory Neuroscience
• Biomechanics of Voice Production

Background:

• Vocal reaction time (RT) is a key measure in understanding speech production.
• Previous research has established typical RT ranges but lacked detailed laryngeal and respiratory system analysis.
• Simultaneous measurement of laryngeal muscle activity and subglottal pressure offers a novel approach to dissecting vocal RT components.

Purpose of the Study:

• To determine the primary limiting factor in vocal reaction time by analyzing the temporal contributions of laryngeal muscles and subglottal air pressure.
• To estimate the minimal central processing time and respiratory system latency during vocalization.
• To differentiate between laryngeal and pulmonary system constraints on vocal RT.

Main Methods:

• 10 male subjects performed a simple vocal reaction time task.
• Simultaneous measurements of intrinsic laryngeal muscle activity (interarytenoid, thyroarytenoid, posterior cricoarytenoid) and subglottal air pressure were recorded.
• Analysis focused on the fastest trial for each subject to identify minimal latencies.

Main Results:

• Mean fastest vocal RT was 185 ms.
• Shortest latencies observed: interarytenoid muscle (50 ms), thyroarytenoid muscle (60 ms), posterior cricoarytenoid muscle (80 ms), subglottal air pressure rise (125 ms).
• Estimated shortest respiratory system latency was 115 ms, and minimal central processing time was 25 ms.

Conclusions:

• Fastest vocal reaction times are principally determined by the temporal constraints of activating the pulmonary system, not the laryngeal muscles.
• The respiratory system latency significantly influences vocal RT, suggesting it's a more critical bottleneck than laryngeal muscle activation.
• These findings provide insights into the neural and biomechanical control of rapid speech production.