Physiological arousal and laughter acoustics

Abstract

Laughter is a ubiquitous human phenomenon that has been little investigated scientifically. To examine the relationship between laugher arousal level and acoustic output, bouts of laughter were recorded from undergraduates viewing humorous video clips. These participants provided continuous subjective ratings of funniness while watching the clips, and heart rate (HR) was collected concurrently to provide an objective measure of physiological arousal. As a first approach, comparisons focused on voiced laughter from nine males and eight females. For each individual, one high-amplitude and one low-amplitude laugh bout was identified for which HR could be extracted. Beats per minute increased significantly more with high-amplitude than low-amplitude bouts, an effect that was not likely due to physical exertion or movement artifact. No sex difference was found in the magnitude of HR change for either amplitude condition. Both subjective ratings of funniness and fundamental-frequency measures were significantly higher for higher-amplitude bouts, while harmonic-to-noise ratios trended lower for these sounds. Overall, results are consistent with the intuition that higher physiological arousal in vocalizers is reflected in higher vocal amplitude and faster, potentially less stable vocal-fold vibration in voiced laughter.