This paper addresses the perceptual relevance of laryngealization as a potential boundary cue in continuous speech utterances. It investigates, in other words, the problem whether the short-time occurrences of various patterns of aperiodic voice vibration frequently found at boundary locations in human speech can actually be perceived and discriminated by human listeners in normal communicative situations, and thus may be taken to contribute (1) to the signal information needed for the correct recognition and inter- pretation of the structural properties of the message, and (2) to the impression of naturalness in human versus computer speech. Four patterns of laryngealization have been examined systematically: glottalization, creaky voice, creak and diplophonic phonation. The results of this study indicate that human listeners evidently exploit aperiodicity in the acoustical speech signal for segmentation but not for classification purposes.