The perception of prominence patterns.

The term 'stress' is used to refer to the perceptual salience at certain places in strings of syllables, but it has several different referents: (a) relative syllable salience in an utterance; this is syllable-, not word-oriented; (b) stress in a word; this is part of the lexical phonology; (c) stressing of words in utterances for various aspects of propositional and expressive meaning, often called 'accent(uation)'. Referents b and c are word- and meaning-oriented. In this article, the terms are more stringently defined. 'Stress' is only used to refer to a lexical stress position (referent b), i.e. a syllable in a word that becomes the docking place for various types of 'accent' to weight words in utterances (referent c). 'Stress' has no physical attributes by itself. 'Prominence' refers to the patterns of salience in syllable strings (referent a). The article reports results of an experiment in prominence perception of the logatome baba, in which the physical parameters F0, syllabic duration, and overall acoustic energy were systematically varied across the bisyllable. Sixteen German subjects had to indicate, by pressing buttons of a computerized reaction time device, whether the first or the second syllable was more prominent. F(0) was a more powerful cue than the other two. Equal syllable duration on a monotone resulted in more first-syllable judgements, which could be counteracted by a slightly falling F(0) contour on the second syllable to reach equal response frequencies for the two syllables. This ties in with Lehiste's earlier findings that F(0) movement increases the perception of duration. Extrapolating from the results, a research programme for prominence perception is developed that will eventually shed new light on the investigation into the nature and manifestation of speech rhythm.