title: Determining the relevance of different aspects of formant contours to intelligibility.
abstract: Previous studies have shown that "clear" speech, where the speaker intentionally tries to enunciate, has better intelligibility than "conversational" speech, which is produced in regular conversation. However, conversational and clear speech vary along a number of acoustic dimensions and it is unclear what aspects of clear speech lead to better intelligibility. Previously, Kain et al. [J. Acoust. Soc. Am.124(4), 2308-2319 (2008)] showed that a combination of short-term spectra and duration was responsible for the improved intelligibility of one speaker. This study investigates subsets of specific features of short-term spectra including temporal aspects. Similar to Kain's study, hybrid stimuli were synthesized with a combination of features from clear speech and complementary features from conversational speech to determine which acoustic features cause the improved intelligibility of clear speech. Our results indicate that, although steady-state formant values of tense vowels contributed to the intelligibility of clear speech, neither the steady-state portion nor the formant transition was sufficient to yield comparable intelligibility to that of clear speech. In contrast, when the entire formant contour of conversational speech including the phoneme duration was replaced by that of clear speech, intelligibility was comparable to that of clear speech. It indicated that the combination of formant contour and duration information was relevant to the improved intelligibility of clear speech. The study provides a better understanding of the relevance of different aspects of formant contours to the improved intelligibility of clear speech.
authors.affiliation: Department of Human Communication Science Devices, House Research Institute 2100 West Third Street, Los Angeles, California 90057.
authors.forename: Akiko
authors.initials: A
authors.lastname: Amano-Kusumoto
authors.affiliation: Center for Spoken Language Understanding (CSLU), Oregon Health & Science University (OHSU) 20000 NW Walker Road, Beaverton, Oregon 97006.
authors.forename: John-Paul
authors.initials: JP
authors.lastname: Hosom
authors.affiliation: Center for Spoken Language Understanding (CSLU), Oregon Health & Science University (OHSU) 20000 NW Walker Road, Beaverton, Oregon 97006.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kain
authors.affiliation: Department of Human Communication Science Devices, House Research Institute 2100 West Third Street, Los Angeles, California 90057.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Aronoff
keywords: speech intelligibility; speech synthesis; vowel perception