The Role of Rhythm and Pitch in the Evaluation of Human Laughter

Human laughter vocalizations are composed of highly variable sounds. We investigated the evaluation of laughter sounds and concentrated especially on the role of two acoustic features of laughter series: specific rhythms and changes in the fundamental frequency. Experimentally modified laughter series were evaluated using listener self-report data. Participants evaluated laughter series with differences in duration (Experiment 1), or in duration and frequencies (Experiment 2) of successive elements. Serial patterns with varying parameters received good ratings that were close to those received for natural laughter. By contrast, series with a stereotyped patterning received poor ratings. In addition, we found that self-report data strongly correlated to participants' direct behavioral reactions while listening to a specific stimulus. We suggest a three-part model to describe mechanisms underlying the evaluation of laughter.