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This study investigates the effect of hyperarticulated, intelligibility‐enhancing clear speech on English speech rhythm. Ramus et al. [Ramus et al., ‘‘Correlates of linguistic rhythm in the speech signal,’’ Cognition 72, 265–292 (1999)] showed that temporal properties of a speech signal such as the percentage of vocalic intervals (%V) and variability of consonantal and vocalic intervals (C, V) can be related to phonological properties such as presence/absence of unstressed vowel reduction and syllable structure complexity, and are consequently quite successful at grouping languages into the traditional rhythmic classes (stress‐, syllable‐, and mora‐timed). Here, we explore whether/how clear speech affects stress‐timed characteristics of English sentences in terms of these measures. Results revealed that the proportion of vocalic intervals (%V) within sentences remained stable across speaking styles, i.e., consonants and vowels were lengthened equally in clear speech. However, variability of both vocalic and consonantal intervals (V, C) was higher in clear than in conversational speech. The increase in V and C was achieved primarily through insertion/strengthening of short vocalic and consonantal segments that were dropped or coarticulated with surrounding sounds in conversational speech, making word and syllable boundaries more salient. These results suggest that increased intelligibility of clear speech can in part be attributed to prosodic structure enhancement by means of enhanced syllable and word boundaries demarcation.This study investigates the effect of hyperarticulated, intelligibility‐enhancing clear speech on English speech rhythm. Ramus et al. [Ramus et al., ‘‘Correlates of linguistic rhythm in the speech signal,’’ Cognition 72, 265–292 (1999)] showed that temporal properties of a speech signal such as the percentage of vocalic intervals (%V) and variability of consonantal and vocalic intervals (C, V) can be related to phonological properties such as presence/absence of unstressed vowel reduction and syllable structure complexity, and are consequently quite successful at grouping languages into the traditional rhythmic classes (stress‐, syllable‐, and mora‐timed). Here, we explore whether/how clear speech affects stress‐timed characteristics of English sentences in terms of these measures. Results revealed that the proportion of vocalic intervals (%V) within sentences remained stable across speaking styles, i.e., consonants and vowels were lengthened equally in clear speech. However, variability of both vocalic a...

This study investigated the effect of hyperarticulated, intelligibility‐enhancing clear speech on global temporal characteristics in paragraph‐length utterances. The results of sentence‐in‐noise listening tests showed a consistent clear speech intelligibility gain across the utterances indicating that the talkers successfully maintained clear speech articulatory modifications throughout the paragraphs. We then explored temporal properties of the speech signal in terms of the percentage and variability of vocalic and consonantal intervals (following Ramus et al., 1999). Consonantal and vocalic intervals were lengthened equally in clear speech: %V remained stable across speaking styles. Moreover, coefficients of variation for both consonantal and vocalic intervals remained stable across clear and conversational speech, suggesting that global temporal properties remain rather stable in the two speaking styles. There was also evidence of an increase in the number of prosodic phrases and of vocalic and consona...

Previous research showed that phonological neighborhood density and word frequency influence word recognition (Luce and Pisoni, 1998) and vowel production (Wright, 2002; Munson and Solomon, 2004; Munson, to appear), suggesting an interaction of lexical and phonetic factors in speech production and perception Here, we explore whether hyperarticulated, intelligibility‐enhancing clear speech shows similar sensitivity to lexical‐level structure. Nine American English talkers (five females, four males) produced 40 monosyllabic easy (frequent words with few lexical neighbors) and hard (infrequent words with many lexical neighbors) words in conversational and clear speech. Twenty‐four subjects participated in a word‐in‐noise listening test. Results revealed a large effect of style on intelligibility and vowel production: words were more intelligible and vowels were longer and more dispersed in clear compared to conversational speech. Moreover, the female talkers produced larger vowel spaces than male talkers in both speaking styles. Vowels in hard words were marginally more dispersed than vowels in easy words in both speaking styles. However, within both speaking styles, easy and hard words were equally intelligible and of approximately equal duration. These results showed that phonetic properties of vowels were enhanced equally in clear speech regardless of their lexical properties.