Alice Turk

A prosody tutorial for investigators of auditory sentence processing

In this tutorial we present evidence that, because syntax does not fully predict the way that spoken utterances are organized, prosody is a significant issue for studies of auditory sentence processing. We describe the basic elements and principles of current prosodic theory, review the psycholinguistic evidence that supports an active role for prosodic structure in sentence representation, and provide a road map of references that contain more complete arguments about prosodic structure and prominence. Because current theories do not predict the precise prosodic shape that a particular utterance will take, it is important to determine the prosodic choices that a speaker has made for utterances that are used in an auditory sentence processing study. To this end, we provide information about practical tools such as systems for signal display and prosodic transcription, and several caveats which we have found useful to keep in mind.

The smooth signal redundancy hypothesis: a functional explanation for relationships between redundancy, prosodic prominence, and duration in spontaneous speech.

This paper explores two related factors which influence variation in duration, prosodic structure and redundancy in spontaneous speech. We argue that the constraint of producing robust communication while efficiently expending articulatory effort leads to an inverse relationship between language redundancy and duration. The inverse relationship improves communication robustness by spreading information more evenly across the speech signal, yielding a smoother signal redundancy profile. We argue that prosodic prominence is a linguistic means of achieving smooth signal redundancy. Prosodic prominence increases syllable duration and coincides to a large extent with unpredictable sections of speech, and thus leads to a smoother signal redundancy. The results of linear regressions carried out between measures of redundancy, syllable duration and prosodic structure in a large corpus of spontaneous speech confirm: (1) an inverse relationship between language redundancy and duration, and (2) a strong relationship between prosodic prominence and duration. The fact that a large proportion of the variance predicted by language redundancy and prosodic prominence is nonunique suggests that, in English, prosodic prominence structure is the means with which constraints caused by a robust signal requirement are expressed in spontaneous speech.

The head-turn preference procedure for testing auditory perception

Abstract The Head-Turn Preference Procedure (HPP) is valuable for testing perception of sustained auditory materials, particularly speech. This article presents a detailed description of the current version of HPP, new evidence of the objectivity of measurements within it, and an account of recent modifications.

Word-boundary-related duration patterns in English

Abstract Segments and syllables with identical distinctive feature specifications in the lexicon can be produced with strikingly different durations in different contexts, depending for example on the location of a lexical word boundary. In a study of 11 triads like tune acquire, tuna choir and tune a choir, durational differences between, e.g.,tune acquire and tuna choir occurred on either side of the word boundary in a variety of prominence contexts, broadly confirming earlier findings in the literature for a more limited set of stimuli. In general, duration measurements fortune ♯a♯choir tokens were found to be intermediate between those oftune ♯acquire and tuna♯choir, suggesting that boundaries at function words are weaker than boundaries between two content words. In addition, an investigation of the distribution of durational differences across and within syllables was conducted to evaluate five duration adjustment mechanisms proposed in the literature. Support was found for word-initial lengthening, polysyllabic shortening, accentual lengthening, and syllable ratio equalization, but not for word-final lengthening.

Language redundancy predicts syllabic duration and the spectral characteristics of vocalic syllable nuclei

The language redundancy of a syllable, measured by its predictability given its context and inherent frequency, has been shown to have a strong inverse relationship with syllabic duration. This relationship is predicted by the smooth signal redundancy hypothesis, which proposes that robust communication in a noisy environment can be achieved with an inverse relationship between language redundancy and the predictability given acoustic observations (acoustic redundancy). A general version of the hypothesis predicts similar relationships between the spectral characteristics of speech and language redundancy. However, investigating this claim is hampered by difficulties in measuring the spectral characteristics of speech within large conversational corpora, and difficulties in forming models of acoustic redundancy based on these spectral characteristics. This paper addresses these difficulties by testing the smooth signal redundancy hypothesis with a very high-quality corpus collected for speech synthesis, and presents both durational and spectral data from vowel nuclei on a vowel-by-vowel basis. Results confirm the duration/language redundancy results achieved in previous work, and show a significant relationship between language redundancy factors and the first two formants, although these results vary considerably by vowel. In general, however, vowels show increased centralization with increased language redundancy.

Multiple targets of phrase-final lengthening in American English words

Abstract Boundary-related lengthening has been shown to affect the phrase-final word in a number of languages, but its precise distribution within the final word has not been determined. Some evidence suggests that it can begin before the final syllable (e.g. in an earlier main-stress syllable), and that it may be progressive (e.g. may affect the coda of the final syllable more than the nucleus and the nucleus more than the onset). However, only a small number of word shapes have been examined in any one language, so the available facts under-determine models of the duration adjustment process. A survey of final lengthening in words with various stress patterns in American English, using acoustic measures, shows that, in the conditions of these experiments, (a) although most of the duration increase occurs in the phrase-final syllable rime, statistically significant lengthening of 7–18% also occurs in the main-stress syllable rime, when the main stress syllable is not the final syllable, (b) this pattern is seen in both pitch-accented and unaccented final words, suggesting that it is not the result of nuclear-accent-related lengthening, (c) the distribution of lengthening across the syllables of the final word is not straightforward, in the sense that regions between the main-stress rime and the final rime appear to be skipped or lengthened less than the regions before and after them. These results suggest that the mechanism of boundary-related lengthening is more complex than current models propose; in particular, its distribution cannot be explained without reference to the location of main lexical stress and appears to involve more than one stretch of speech, at least in American English.

Spectro-temporal processing during speech perception involves left posterior auditory cortex.

This functional magnetic resonance imaging study investigates the neural underpinnings of spectro-temporal integration during speech perception. Participants performed an auditory discrimination task on a set of sine-wave analogues that could be perceived as either nonspeech or speech. Behavioural results revealed a difference in the processing mode; spectro-temporal integration occurred during speech perception, but not when stimuli were perceived as nonspeech. In terms of neuroimaging, we observed an activation increase in the left posterior primary and secondary auditory cortex, namely Heschls gyrus and planum temporale encroaching onto the superior temporal sulcus, reflecting a shift from auditory to speech perception. This finding demonstrates that the left posterior superior temporal lobe is essential for spectro-temporal processing during speech perception.

Phonetic Structures of Scottish Gaelic

Scottish Gaelic is an endangered language with very few fluent speakers under 60. Recordings were collected in the neighbourhood of Greater Bernera, Lewis, from 11 native speakers. Aerodynamic and palatographic data were collected from one 70-year-old male speaker. Palatographic data made in 1955 by Frederick Macaulay, a Gaelic speaker from South Uist, provided additional information. Analysis showed that all the stops were voiceless unaspirated or aspirated, with the aspirated stops being preaspirated intervocalically. Spectra of various consonants were also determined. Vowel analyses showed the nature of the 7 long and short vowels. Special attention was paid to the back unrounded vowels. Problems of syllabicity were examined and shown to affect pitch contours.

English words on the Procrustean bed: Polysyllabic shortening reconsidered

Abstract The polysyllabic shortening hypothesis holds that the duration of a primary stressed syllable is inversely proportional to the number of additional syllables within the word. We examine the evidence for this process in British English speech by measuring the duration of primary stressed syllables in monosyllabic, disyllabic and trisyllabic words, both right-headed series – e.g. mend , commend , recommend – and left-headed series – e.g. mace , mason , masonry . In contrast with some of the original studies of polysyllabic shortening (e.g. Lehiste, 1972 ), we record target words both when carrying nuclear pitch accent and when unaccented. As in previous studies, we find strong evidence of polysyllabic shortening in accented words, an effect of comparable magnitude in right-headed and left-headed words. In unaccented words, polysyllabic shortening is minimal or absent, but there is evidence, supporting previous studies, of domain-edge effects localised to specific sub-syllabic constituents. Unlike these effects, which occur on both pitch-accented and unaccented words, polysyllabic shortening of the primary stressed syllable in these data is confined to pitch-accented words.

Utterance-final lengthening and quantity in Northern Finnish

Abstract Utterance-final lengthening in Northern Finnish was investigated using tightly controlled laboratory materials, with particular focus on its interaction with the languages single (short) vs. double (long) vowel distinction. Like many other languages, Finnish exhibited utterance-final lengthening, although the estimates of magnitudes of lengthening on final vowels varied greatly depending on the treatment of the utterance-final breathy/voiceless portion of the vowel. As has been also shown for other languages, the lengthening occurred as early as the stressed, penultimate syllable of disyllabic words and was generally progressive. Crucially, vowel quantity interacted with the lengthening in a manner consistent with a hypothesis that Finnish regulates utterance-final lengthening to preserve its quantity system. Specifically, the voiced portion (the portion that is relevant to the perception of vowel quantity) of the longest single vowel (the half-long vowel) was restricted. Additionally, double vowels were lengthened less when the vowel in an adjacent syllable was also double, suggesting syntagmatic constraints. Our results support the view that utterance-final lengthening is a universal tendency but is implemented in language-specific ways and must be learned.