Effects of talk-spurt silence boundary thresholds on distribution of gaps and overlaps

Faced with lack of objective and easily applicable criteria for segmentation of speech into dialogue turns, many authors resort instead to units defined in terms of stretches of speech minimally bounded by silence of some predefined duration. There is, however, no consensus concerning silence thresholds employed. While such thresholds can be established on perceptual grounds, in practice a wide range of values is used. As this has a direct impact on the reported frequencies of silences and overlaps, the discrepancies make comparisons of results across different studies difficult. In an attempt to overcome these problems in the present paper we use the Switchboard corpus to evaluate the expected variability in distributions of inter- and intra-speaker intervals when silence boundary thresholds of inter-pausal units are manipulated. Index Terms: dialogue segmentation, inter-pausal units, gaps and overlaps