The effect of position in utterance on speech segment duration in English

The duration of speech segments as a function of position in utterances (initial, medial, final) was studied. In the first experiment seven English speakers read nonsense utterances of the form “say a bab, say a bábab, say a babáb,” etc. Spectrograms were used to determine the duration of speech segments in the readings. Final syllables were found to be longer than nonfinal syllables. Final-syllable vowel increments were approximately 100 msec. Final-syllable consonant increments were less than vowel increments; for instance, absolute final consonant increments were about 20 msec. Also word-initial consonants were found to be lengthened by 20–30 msec over medial consonants. Subsequent experimentation demonstrated with English nonsense words that (1) final-syllable and initial-consonant lengthening occur in utterances with various intonational patterns (imperative, declarative, interrogative); (2) final-syllable lengthening occurs in word-final and phrase-final positions as well as in utterance-final position; and (3) final-syllable and initial-consonant lengthening occur in various kinds of syllables, including syllables with diphthongs, with fricative consonants, with voiceless stops, with consonant cluster, and with no final consonants (i.e., CV syllables). These studies report durational increments of particularly great magnitude for absolute final fricative consonants. Explanations of the lengthening effects are discussed. One theory suggests that lengthening in certain utterance positions is a learned aspect of language which cues listeners concerning the location of boundaries of words, phrases, or sentences. Explanations based on hypothesized properties of the speech production process are also discussed.