Figure 1.

Human and animal affective vocalizations. (a–d) Spectrograms (0–11 025 Hz) of examples of stimuli from each of the four categories of vocalizations. (a) Human positive vocalization: sexual pleasure. (b) Human negative vocalization: scream of fear. (c) Animal positive vocalization: monkey harmonic arch. (d) Animal negative vocalization: monkey scream. (e) Ratings of perceived affective valence on a 0–100 visual analogue scale (0, extremely negative; 100, extremely positive). Note the absence of difference in perceived valence for the animal vocalizations. (f) Long-term average spectrum for the four sound categories.