Properties of the duration of English rhythm segments

With the aim of describing the periodicity of English rhythm, this study investigated the properties of the duration of rhythm segments that comprised a set of stressed and unstressed syllables. The data were the speech sounds of short sentences, each including three to five stressed syllables, spoken by a total of 20 native speakers. Five rhythm segment structures were identified based on the location of the stressed syllable and adopted for comparative judgment. They were as follows: a stressed syllable backward, semibackward, middle, semiforward, and forward in a segment. The measurement based on the detailed acoustical analysis showed that the reasonable rhythm segment structure can be defined as existing somewhere around FORWARD and SEMIFORWARD. In these structures, the periodicity of the rhythm is clearly shown in the duration of the rhythm segment. Furthermore, it was revealed that the duration of a rhythm segment with a secondary stress distributed around a half of that of a rhythm segment with a primary stress. That is, the rhythm can be described by a series of the basic periods and its half periods.