Not all laughs are alike: voiced but not unvoiced laughter readily elicits positive affect.

We tested whether listeners are differentially responsive to the presence or absence of voicing, a salient, distinguishing acoustic feature, in laughter. Each of 128 participants rated 50 voiced and 20 unvoiced laughs twice according to one of five different rating strategies. Results were highly consistent regardless of whether participants rated their own emotional responses, likely responses of other people, or one of three perceived attributes concerning the laughers, thus indicating that participants were experiencing similarly differentiated affective responses in all these cases. Specifically, voiced, songlike laughs were significantly more likely to elicit positive responses than were variants such as unvoiced grunts, pants, and snortlike sounds. Participants were also highly consistent in their relative dislike of these other sounds, especially those produced by females. Based on these results, we argue that laughers use the acoustic features of their vocalizations to shape listener affect.