Acoustic correlates of talker-reported clear strategies

Abstract

When asked to speak clearly, talkers vary considerably in terms of the amount of intelligibility benefit achieved. The acoustic differences between clear and conversational speech also differ from talker to talker. The present study examined the extent to which clear speech acoustic modifications were consistent with talkers’ descriptions of the strategies they used in the clear speech condition during the recording of a large multitalker database [S. H. Ferguson, J. Acoust. Soc. Am. 116, 2365–2373 (2004)]. Specifically, talkers who did and did not report placing extra stress on keywords in clear speech were compared on a variety of duration, pitch, and amplitude metrics. Results will be discussed in terms of talker differences in awareness of and control of specific aspects of speech production. Clinical implications will also be discussed.

Effects of speech style, room acoustics, and vocal fatigue on vocal effort

“…For example, when conversing with a listener who has hearing limitations, a typical talker uses "clear speech." Such speech has been characterized by a slower speech rate, a wider range of fundamental frequency (fo), and a higher temporal modulation index than conversational speech (e.g., Picheny et al, 1985;Ferguson et al, 2010).…”

Acoustic correlates of vowel intelligibility in clear and conversational speech for young normal-hearing and elderly hearing-impaired listeners

“…That is, talkers may open their mouths wider in order to become louder, resulting in a lower tongue position for all vowels. Ferguson et al (2010) reported that on average, the present talkers spoke with 4 dB greater intensity in clear speech than conversational speech. The association between increased vocal intensity and increased F1 was explored by correlating unpublished speech intensity data from Ferguson (2002) with the average F1 change each talker produced in clear speech.…”

“…Ferguson and Kewley-Port (2007) reported vowel acoustic data for 10 of the 41 talkers and reported a clear/conversational vowel duration ratio of 1.4. In addition, Ferguson et al (2010) measured speaking rate for all 41 talkers using sentence materials; the mean speaking rate in clear speech was 111 words per minute, significantly slower than the conversational speaking rate of 155 words per minute. Studies using other recorded materials have also reported longer vowel durations in clear speech.…”

“…Talkers speaking clearly speak more slowly (Picheny et al, 1986;Bradlow et al, 2003;Smiljanic and Bradlow, 2005;Smiljanic and Bradlow, 2008;Ferguson et al, 2010;Rosen et al, 2011;Lam et al, 2012) and more loudly (Picheny et al, 1986;Ferguson et al, 2010;Hazan and Baker, 2011; 2 Lam et al, 2012) and with a higher voice pitch (Bradlow et al, 2003;Hazan and Baker, 2011). Talkers also use a more variable voice pitch in clear speech than in conversational speech (Picheny et al, 1986;Bradlow et al, 2003;Hazan and Baker, 2011).…”

“…Talkers also use a more variable voice pitch in clear speech than in conversational speech (Picheny et al, 1986;Bradlow et al, 2003;Hazan and Baker, 2011). These global clear speech acoustic changes are accompanied by phoneme-level changes such as stronger final consonants (Picheny et al, 1986;Bradlow et al, 2003;Ferguson et al, 2010) and vowel modifications including an expanded vowel space (Picheny et al, 1986;Ferguson and Kewley-Port, 2002;Bradlow et al, 2003;Smiljanic and Bradlow, 2005;Ferguson and Kewley-Port, 2007;Ferguson et al, 2010;Hazan and Baker, 2011;Lam et al, 2012), greater dynamic formant movement (Ferguson and KewleyPort, 2002;Ferguson and Kewley-Port, 2007;Lam et al, 2012), and longer vowel durations (Ferguson and KewleyPort, 2002;Ferguson and Kewley-Port, 2007;Picheny et al, 1986;Lam et al, 2012). Similar vowel modifications have been observed in studies comparing "hyperarticulated" and citation-style speech (e.g., Moon and Lindblom, 1994).…”