Speech rhythm: the language-specific integration of pitch and duration

Experimental phonetic research on speech rhythm seems to have reached an impasse. Recently, this research field has tended to investigate produced (rather than perceived) rhythm, focussing on timing, i.e. duration as an acoustic cue, and has not considered that rhythm perception might be influenced by native language. Yet evidence from other areas of phonetics, and other disciplines, suggests that an investigation of rhythm is needed which (i) focuses on listeners’ perception, (ii) acknowledges the role of several acoustic cues, and (iii) explores whether the relative significance of these cues differs between languages. This thesis, the originality of which derives from its adoption of these three perspectives combined, indicates new directions for progress. A series of perceptual experiments investigated the interaction of duration and f0 as perceptual cues to prosody in languages with different prosodic structures – Swiss German, Swiss French, and French (i.e. from France). The first experiment demonstrated that a dynamic f0 increases perceived syllable duration in contextually isolated pairs of monosyllables, for all three language groups. The second experiment found that dynamic f0 and increased duration interact as cues to rhythmic groups in series of monosyllabic digits and letters; the two cues were significantly more effective than one when heard simultaneously, but significantly less effective than one when heard in conflicting positions around the rhythmic-group boundary location, and native language influenced whether f0 or duration was the more effective cue. These two experiments laid the basis for the third, which directly addressed rhythm. Listeners were asked to judge the rhythmicality of sentences with systematic duration and f0 manipulations; the results provide evidence that duration and f0 are interdependent cues in rhythm perception, and that the weighting of each cue varies in different languages. A fourth experiment applied the perceptual results to production data, to develop a rhythm metric which captures the multi-dimensional and language-specific nature of perceived rhythm in speech production. These findings have the important implication that if future phonetic research on rhythm follows these new perspectives, it may circumvent the impasse and advance our knowledge and model of speech rhythm.This work was funded by an AHRC doctoral award to the author

Lexical and postlexical prominence in Tashlhiyt Berber and Moroccan Arabic

Tashlhiyt Berber (Afro-Asiatic, Berber) and Moroccan Arabic (Afro-Asiatic, Semitic), two languages spoken in Morocco, have been in contact for over 1200 years. The influence of Berber languages on the lexicon and the segmental-phonological structure of Moroccan Arabic is well-documented, whereas possible similarities in the prosodic-phonological domain have not yet been addressed in detail. This thesis brings together evidence from production and perception to bear on the question whether Tashlhiyt Berber and Moroccan Arabic also exhibit convergence in the domain of phonological prominence. Experimental results are interpreted as showing that neither language has lexical prominence asymmetries in the form of lexical stress. This lack of stress in Moroccan Arabic is unlike the undisputed presence of lexical stress in most other varieties of Arabic, which in turn suggests that this aspect of the phonology of Moroccan Arabic has resulted from contact with (Tashlhiyt) Berber. A further, theoretical contribution is made with respect to the possible correspondence between lexical and postlexical prominence structure from a typological point of view. One of the tenets of the Autosegmental Metrical approach to intonation analysis holds that prominence-marking intonational events (pitch accents) associate with lexically stressed syllables. Exactly how prominence marking is achieved in languages that lack lexical stress is little-understood, and this thesis' discussion of postlexical prominence in Tashlhiyt Berber and Moroccan Arabic provides new insights that bear on this topic. A first set of production experiments investigates, for both languages, if there are acoustic correlates to what some researchers have considered to be lexically stressed syllables. It is shown that neither language exhibits consistent acoustic enhancement of presumed stressed syllables relative to unstressed syllables. The second set of production experiments reports on the prosodic characteristics of question word interrogatives in both languages. It is shown that question words are the locus of postlexical prominence-marking events that however do not exhibit association to a sub-lexical phonological unit. A final perception experiment serves the goal of showing how native speakers of Tashlhiyt Berber and Moroccan Arabic deal with the encoding of a postlexical prominence contrast that is parasitic on a lexical prominence contrast. This is achieved by means of a 'stress deafness' experiment, the results of which show that speakers of neither language can reliably encode a lexically-specified prominence difference. Results from all three types of experiment thus converge in suggesting that lexical prominence asymmetries are not specified in the phonology of either language

Tonal placement in Tashlhiyt: How an intonation system accommodates to adverse phonological environments

In most languages, words contain vowels, elements of high intensity with rich harmonic structure, enabling the  perceptual retrieval of pitch. By contrast, in Tashlhiyt, a Berber language, words can be composed entirely of voiceless segments. When an utterance consists of such words, the phonetic opportunity for the execution of intonational pitch movements is exceptionally limited. This book explores in a series of production and perception experiments how these typologically rare phonotactic patterns interact with intonational aspects of linguistic structure. It turns out that Tashlhiyt allows for a tremendously flexible placement of tonal events. Observed intonational structures can be conceived of as different solutions to a functional dilemma: The requirement to realise meaningful pitch movements in certain positions and the extent to which segments lend themselves to a clear manifestation of these pitch movements

Tonal placement in Tashlhiyt: How an intonation system accommodates to adverse phonological environments

In most languages, words contain vowels, elements of high intensity with rich harmonic structure, enabling the  perceptual retrieval of pitch. By contrast, in Tashlhiyt, a Berber language, words can be composed entirely of voiceless segments. When an utterance consists of such words, the phonetic opportunity for the execution of intonational pitch movements is exceptionally limited. This book explores in a series of production and perception experiments how these typologically rare phonotactic patterns interact with intonational aspects of linguistic structure. It turns out that Tashlhiyt allows for a tremendously flexible placement of tonal events. Observed intonational structures can be conceived of as different solutions to a functional dilemma: The requirement to realise meaningful pitch movements in certain positions and the extent to which segments lend themselves to a clear manifestation of these pitch movements

Acoustic correlates of lexical stress in Moroccan Arabic

Presently there is no consensus regarding the interpretation and analysis of the stress system of Moroccan Arabic. This paper tests whether the acoustic realisation of syllables support one widely adopted interpretation of lexical stress, according to which stress is either penultimate or final depending on syllable weight. The experiment reports on word-initial syllables that differ in presumed stress status. Target words were embedded in a carrier sentence within a scripted mock dialogue to ensure that the measurements reflect lexical stress rather than phrase-level prominence. Results from all four acoustic parameters tested (f0, duration, Centre of Gravity and vowel quality) showed that there were no differences as a function of presumed stress status, thus failing to support an interpretation according to which stressed syllables are acoustically differentiated. We consider the results in relation to previous claims and observations, and conclude that the absence of acoustic correlates of presumed stress is compatible with the view that Moroccan Arabic lacks lexical stress

Tonal placement in Tashlhiyt: How an intonation system accommodates to adverse phonological environments

In most languages, words contain vowels, elements of high intensity with rich harmonic structure, enabling the  perceptual retrieval of pitch. By contrast, in Tashlhiyt, a Berber language, words can be composed entirely of voiceless segments. When an utterance consists of such words, the phonetic opportunity for the execution of intonational pitch movements is exceptionally limited. This book explores in a series of production and perception experiments how these typologically rare phonotactic patterns interact with intonational aspects of linguistic structure. It turns out that Tashlhiyt allows for a tremendously flexible placement of tonal events. Observed intonational structures can be conceived of as different solutions to a functional dilemma: The requirement to realise meaningful pitch movements in certain positions and the extent to which segments lend themselves to a clear manifestation of these pitch movements

On the variability in Fo patterning and the function of Fo timing in languages where pitch cues stress

The basic property of pitch as a cue to linguistic stress is fundamental frequency (Fo) change. That leaves room for a lot of variation: in the direction of the change, the amount of change, and its exact coordination with the stressed syllable. Examples (from the  literature) from a number of languages and dialects attest that they do indeed exhibit quite striking differences in the stress/Fo relationship. The decisiveness, under certain circumstances, of the timing of Fo events is illustrated by the results of a pilot experiment with a disyllabic Danish word: the location of a two semitone rise from the first to the second syllable - before or after the intervocalic sonorant consonant - will shift listeners' location of the stress

Why stress position bias?

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Describing Events: Changes in Eye Movements and Language Production Due to Visual and Conceptual Properties of Scenes

Esaulova Y, Penke M, Dolscheid S. Describing Events: Changes in Eye Movements and Language Production Due to Visual and Conceptual Properties of Scenes. Frontiers in Psychology. 2019;10: 835