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Certain types of speech, e.g. lists of words or numbers, are usually spoken withhighly regular inter-stress timing. The main hypothesis of this study (derived fromthe Dynamic Attending Theory) is that listeners attend in particular to speech eventsat these regular time points. Better timing regularity should improve spoken-wordperception. Previous studies have suggested only a weak effect of speech rhythm onspoken-word perception, but the timing of inter-stress intervals was not controlledin these studies. A phoneme monitoring experiment is reported, in which listenersheard lists of disyllabic words in which the timing of the stressed vowels was eitherregular (with equidistant inter-stress intervals) or irregular. In addition, metricalexpectancy was controlled by varying the stress pattern of the target word, as eitherthe same or the opposite of the stress pattern in its preceding words. Resulting reac-tiontimes show a main effect of timing regularity, but not of metrical expectancy.These results suggest that listeners employ attentional rhythms in spoken-word per-ception,and that regular speech timing improves speech communication.

Russian exhibits a rich pattern of phonological vowel reduction, by which somevowel contrasts are neutralized in unstressed syllables. Recent work in phonologysuggests a mechanism by which phonetic vowel reduction - compression of theoverall vowel space due to target undershoot - might lead to patterns like Russian.Presenting acoustic data from 9 speakers of Russian, we use Euclidean distancemeasures, measures of F1-F0 and F2-F1, and Bayesian classification to provide abasic picture of how the overall vowel space, as well as the distribution of vowels,change as stress is reduced. We are particularly interested in whether contraction ofthe vowel space in unstressed positions is primarily due to raising, and in whethercontrasting pairs of vowels are evenly spaced within and across contexts. Ourresults provide qualified support for the first hypothesis, but largely do not supportthe hypothesis of equal spacing, in particular across contexts. Of additional interest,we find that some impressionistically described neutralizations are incomplete.