What determines duration-based rhythm measures: text or speaker?

Abstract

Differences in rhythm between languages have been often attributed to differences in phonological properties such as syllable structure. This paper uses quantitative analyses to determine whether and how popular duration-based rhythm measures depend on the phonological structure of a language. Native speakers of five languages read a large corpus of comparable texts (approximately 371,000 syllables in total). Phonological properties of each language were specified as 11 variables, computed from the phonetic transcriptions. These variables were compared against published rhythm measures that captured variation in duration of consonantal and vocalic intervals. While the text-based measures discriminated well between languages, the values of rhythm measures overlapped substantially, showing that the languages are more alike in acoustic implementation than in their phonological description. Multilevel models demonstrated that the mapping between phonological properties and acoustics is much weaker than previously assumed: linear effects of the phonological variables explained less than a quarter of the total variance in rhythm measures. Instead, speaker was the main source of variation in those measures. Rhythm, in the sense of durational variability, depends far more on individual timing strategies than on the phonological structure of a language.