Timing patterns in fluent and disfluent spontaneous speech

Most previous acoustic analysis of speech has examined data from speakers who carefully pronounce their speech, usually by reading prepared texts. Natural spontaneous or conversational speech differs from careful or read speech, especially concerning hesitation phenomena and variable speaking rates. We examine and model global speaking rate, how it varies for both fluent and disfluent spontaneous speech, in terms of the linguistic content of the utterances. Speakers tend to maintain a fixed speaking rate during most utterances, but often adopt a faster or slower rate, depending on the cognitive load (i.e., slowing down when having to make unanticipated choices, or accelerating when repeating some words). Such a model can find application in automatic speech synthesis and recognition, because most synthesizers maintain a constant (and unnatural) speaking rate and most recognizers are not capable of adapting their templates or probabilistic models to reflect global changes in speaking rate