Formant transitions in varied utterance positions

Abstract

Aim: Acoustic characteristics associated with varied utterance positions were examined to understand the acoustic consequences of potential articulatory changes near utterance boundaries. Methods: Second formant transition characteristics, including transition duration (ms), transition extent (Hz), and derived slope of transition (Hz/ms), of 12 healthy speakers of American English were examined for two diphthong transitions in sew and sigh and one consonant-vowel transition in bee in utterance-initial, utterance-final, and utterance-end positions. Speakers performed a task of contrastive stress variation that served to demonstrate the changeability of acoustic characteristics as an index of articulatory change in shaping the vocal tract. Results: Contrastive stress, as compared to words spoken without increased stress, was associated with longer transition duration, greater transition extent, and a decreased slope. Although some utterance position effects were present, no systematic differences consistent with boundary strengthening or declination were found. Conclusion: Findings suggest that varied utterance positions may be associated with stimulus-dependent variation in articulatory changes that is reflected in the acoustic output. These results indicate the need to further understand the construct of utterance-level speech materials, such as carrier phrases, in clinical practice and research. © 2013 S. Karger AG, Basel.