Mutual interference between rhythmic tapping and speech production

Humans have the natural ability to synchronize their movements with rhythm, which plays a key role in social interaction, coordination, and emotional expression. Recent studies have suggested that this rhythmic ability may share neural mechanisms with vocal learning, as observed in certain animal species that are capable of vocal mimicry. This study aimed to examine whether the human rhythm generation mechanism contributes to speech production. We conducted a behavioral experiment to investigate the mutual interference between rhythmic finger tapping and speech. Participants first began tapping their fingers at a steady pace. Once a sentence appeared on a monitor, they read it aloud while continuing to tap. Both speech and tapping sounds were recorded. Two tapping conditions were used: isochronous tapping and non-isochronous tapping with 1:1 and 2:1 interval ratios, respectively. We calculated the standard deviation of the log-transformed ratio between observed and ideal tap intervals to quantify tapping variability. Results showed that the variability index increased after sentence presentation, particularly in the 2:1 rhythm condition. This finding demonstrates that speech production disrupts rhythmic motor activity, especially under complex rhythmic patterns. This insight may enhance the understanding and development of interventions for speech disfluency in stuttering and dyslexia.