FIG. 11.

(Color online) The marmoset utters a variety of short duration calls classified as “peeps” which were divided into five types. Time waveforms and spectrograms of the five observed simple peep types are shown. In general, the p-peep resembles a very short phee, the t-peep resembles a very short trill, the sa-peep is characterized by a steeply rising FM sweep, the sd-peep is characterized by a steeply falling FM sweep, and the dh-peep is a declining FM sweep that blends into an FM arch. Unlike other calls such as the phee and twitter, there is a high degree of variability in time-frequency characteristics within each of the peep types.