EFFECTS OF STRESS AND LEXICAL STRUCTURE ON SPEECH EFFICIENCY

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R.J.J.H. van Son and Louis C.W. Pols
Institute of Phonetic Sciences/IFOTT
University of Amsterdam
Herengracht 338, 1016 CG Amsterdam, The Netherlands
tel: +31 20 5252183; fax: +31 20 5252197; email: {rob, pols}@fon.hum.uva.nl

ABSTRACT


It is proposed that some of the variation in speech is the result of an effort to communicate efficiently. Speaking is considered efficient if the speech sound contains only the information needed to understand it. This efficiency is tested by means of a corpus of spontaneous and matched read speech, and syllable, word, and N-gram frequencies as measures of information content (1582 intervocalic consonants, and 2540 vowels). It is indeed found that the duration and spectral reduction of consonants and vowels from stressed syllables correlate with syllable and word frequencies, as does consonant intelligibility. Correlations for phonemes from unstressed syllables are generally weaker or absent. N-gram models of word predictability did not correlate with any of the factors investigated. Simple N-grams seem to be a poor model for human word prediction. It is concluded that the principle of efficient communication organizes at least some aspects of speech production.