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Listeners resolve ambiguities in speech perception using multiple sources, including non-local or distal speech rate (i.e., the speech rate of material surrounding a particular region). The ability to resolve ambiguities is particularly important for the perception of casual, everyday productions, which are often produced using phonetically reduced forms. Here, we examine whether the distal speech rate effect is specific to a lexical class of words and/or to particular lexical or phonological contexts. In Experiment 1, we examined whether distal speech rate influenced perception of phonologically similar content words differing in number of syllables (e.g., form/forum). In Experiment 2, we used both transcription and word-monitoring tasks to examine whether distal speech rate influenced perception of a reduced vowel, causing lexical reorganization (e.g., cease, see us). Distal speech rate influenced perception of lexical content in both experiments. This demonstrates that distal rate influences perception of a lexical class other than function words and affects perception in a variety of phonological and lexical contexts. These results support a view that distal speech rate is a pervasive source of information with far-reaching consequences for perception of lexical content and word segmentation.

Persuasiveness in oral communication in English can be expressed with various vocal phonetic cues that may not be readily accessible to English second language (L2) learners whose native language may employ a different set of cues. With a goal to increase L2 learners’ perceived spoken confidence and persuasiveness, and obtain empirical evidence for phonetic adjustments that native English speakers make to influence listeners, the current study explored the use of consonant prolongation in stressed syllable onsets for emphasis by native British English speakers and English L2 learners. The native speakers’ durations of continuant consonants and voiceless stop consonant voice onset times (VOTs) in (1) neutrally-produced speech and (2) persuasively delivered motivational/shocking/emotional messages were compared to Latvian L2 English speakers’ productions. The results revealed that in persuasive speech, the British speakers’ consonantal durations, particularly those of continuants, got significantly longer relative to the vowels that followed them; for English L2 learners, the duration of consonants did not change as a factor of speech type. This is in line with our previous research with American English speakers and carries implications for L2 speech learning and teaching.

Recent findings [Dilley and Pitt, 2010. Psych. Science. 21, 1664-1670] have shown that manipulating context speech rate in English can cause entire syllables to disappear or appear perceptually. The current studies tested two rate-based explanations of this phenomenon while attempting to replicate and extend these findings to another language, Russian. In Experiment 1, native Russian speakers listened to Russian sentences which had been subjected to rate manipulations and performed a lexical report task. Experiment 2 investigated speech rate effects in cross-language speech perception; non-native speakers of Russian of both high and low proficiency were tested on the same Russian sentences as in Experiment 1. They decided between two lexical interpretations of a critical portion of the sentence, where one choice contained more phonological material than the other (e.g., /stərʌ'na/ “side” vs. /strʌ'na/ “country”). In both experiments, with native and non-native speakers of Russian, context speech rate and the relative duration of the critical sentence portion were found to influence the amount of phonological material perceived. The results support the generalized rate normalization hypothesis, according to which the content perceived in a spectrally ambiguous stretch of speech depends on the duration of that content relative to the surrounding speech, while showing that the findings of Dilley and Pitt (2010) extend to a variety of morphosyntactic contexts and a new language, Russian. Findings indicate that relative timing cues across an utterance can be critical to accurate lexical perception by both native and non-native speakers.