Metrical Structure Research Articles

Metrical structure and sung rhythm of the Hausa rajaz

The rajaz meter of Hausa is based on syllable quantity. In its dimeter form, it deploys lines consisting of two metra, each usually containing six moras. A variety of metra occur, and the key analytic challenge is to single out the legal metra from the set of logically possible ones. We propose an analysis, framed in maximum entropy optimality theory, that does this and also accounts for the statistical distribution of metron types, varying from poem to poem, within the line and stanza. We demonstrate a law of comparative frequency for rajaz and show how it emerges naturally in the maxent framework when competing candidates are in a relationship of harmonic bounding.

Apparent exceptions to final devoicing in High Prussian: A metrical analysis

High Prussian, a variety of East Central German, has a segmentally opaque process of final devoicing: Only some forms with underlyingly voiced obstruents devoice at the end of a word. This phenomenon can also be observed in some morphological alternations where simplex forms show final devoicing but complex ones do not. This paper provides a metrical analysis of final devoicing and two related phenomena: spirantization, and an interaction of vowel length in high vowels and obstruent voicing. It is claimed that nondevoicing items contain disyllabic foot templates and that word-final consonants are then syllabified as onsets of empty-headed word-final syllables. The analysis demonstrates how evidence from West Germanic dialects can contribute to our understanding of the phonology of laryngeal features and to the role that metrical structure can play in shaping phonological alternations.*

Influence of metrical structure on learning of positional regularities in movement sequences.

Sequential stimuli are usually perceived to have hierarchical temporal structures. However, some of these structures are only investigated in one type of sequence, regardless of the existing evidence, showing the domain-generality of the representation of these structures. Here, we assess whether the hierarchical representation of regularly segmented action sequences resembles the perceived metrical patterns that organize the representation of events hierarchically in temporally regular sequences. In all our experiments, we presented the participants with sequences of human movements and tested the perception of metrical pattern by segmenting the movement streams into temporally equal groups containing four movements. In Experiment 1, we found that a movement sequence with temporally equal groupings improves the learning of positional regularities inherent within each group of movements. To further clarify the degree to which this learning mechanism is affected by the perceived metrical patterns, we conducted Experiments 2a and 2b, in which the relative saliencies of the first and last positions in the movement groups, respectively, were studied. The results showed that, although in the learning of positional regularities, the rule-conforming first positions are as effective as when both first and last positions are legal, the last positions are not as influential. Based on these findings we conclude that, in grouped sequences, learning of positional regularities may be modulated by the metrical saliency patterns that are imposed by the temporal regularity of the sequential grouping pattern.

A cross-linguistic study of phonetic correlates of metrical structure in under-documented languages

Although languages with rhythmic stress have been extensively described and analyzed in the phonology literature, there has been little phonetic verification of the metrical structures suggested by these stress patterns. This paper presents results of a cross-linguistic study of the acoustic correlates of foot structure in several under-documented languages with morphologically complex words providing the necessary backdrop for the realization of rhythmic metrical structure. Various potential acoustic exponents of metrical structure are considered, including duration, F0, intensity, and formant frequencies. The targeted languages include Muskogean languages of the United States (Koasati, Muskogee, and Chickasaw), Circassian languages spoken primarily in Turkey and Russia (Kabardian and Adyghe), the Tukanoan language Kubeo of Brazil and Colombia, and the Arawak language Mojeno Trinitario of Bolivia. The languages differ in their foot templates (trochaic vs. iambic), the direction of their metrical parse (left-to-right vs. right-to-left), their degree of metrical rhythm, and whether they also possess lexical tone or not. Results suggest considerable diversity in the acoustic manifestations of metrical structure (including the possibility of lack of rhythmic feet even in long words) and in the relationship between the word-level metrical system and other prosodic features, including intonation and (in tonal languages) lexical tone.Although languages with rhythmic stress have been extensively described and analyzed in the phonology literature, there has been little phonetic verification of the metrical structures suggested by these stress patterns. This paper presents results of a cross-linguistic study of the acoustic correlates of foot structure in several under-documented languages with morphologically complex words providing the necessary backdrop for the realization of rhythmic metrical structure. Various potential acoustic exponents of metrical structure are considered, including duration, F0, intensity, and formant frequencies. The targeted languages include Muskogean languages of the United States (Koasati, Muskogee, and Chickasaw), Circassian languages spoken primarily in Turkey and Russia (Kabardian and Adyghe), the Tukanoan language Kubeo of Brazil and Colombia, and the Arawak language Mojeno Trinitario of Bolivia. The languages differ in their foot templates (trochaic vs. iambic), the direction of their metrical parse (l...

Verse texts in the Latin inscriptions of Estonian ecclesiastical space: meter, rhythm and prosody

In 2014, the project CEILE (Corpus Electronicum Inscriptionum Latinarum Estoniae, EKKM 14-364) was launched within the framework of the program “Estonian language and cultural memory”, in order to systematically map and study the Latin inscriptions created before 1918 and stored in Estonian Lutheran and Catholic churches. As of 2018, the database contains more than 300 inscriptions. Although the proportion of verse texts is not high (13 entries), the fact that the material (totalling 175 verses) has survived almost completely, part of them in situ and partly in transcriptions, and contains several lengthier texts, allows us to make certain generalizations about their metrical and prosodic structure. In this paper, we will give an overview of the chronology and sites of inscriptions and describe the metrical, rhythmical and prosodic structure of the verse texts, addressing also the conjectural role of meter and prosody in our work. We will also dwell on the metrical and prosodic correctness of the texts and will take a separate look at the prosodic licences and errors which occur in the verse texts of the corpus.

Rhesus Monkeys (Macaca mulatta) Sense Isochrony in Rhythm, but Not the Beat: Additional Support for the Gradual Audiomotor Evolution Hypothesis.

Charles Darwin suggested the perception of rhythm to be common to all animals. While only recently experimental research is finding some support for this claim, there are also aspects of rhythm cognition that appear to be species-specific, such as the capability to perceive a regular pulse (or beat) in a varying rhythm. In the current study, using EEG, we adapted an auditory oddball paradigm that allows for disentangling the contributions of beat perception and isochrony to the temporal predictability of the stimulus. We presented two rhesus monkeys (Macaca mulatta) with a rhythmic sequence in two versions: an isochronous version, that was acoustically accented such that it could induce a duple meter (like a march), and a jittered version using the same acoustically accented sequence but that was presented in a randomly timed fashion, as such disabling beat induction. The results reveal that monkeys are sensitive to the isochrony of the stimulus, but not its metrical structure. The MMN was influenced by the isochrony of the stimulus, resulting in a larger MMN in the isochronous as opposed to the jittered condition. However, the MMN for both monkeys showed no interaction between metrical position and isochrony. So, while the monkey brain appears to be sensitive to the isochrony of the stimulus, we find no evidence in support of beat perception. We discuss these results in the context of the gradual audiomotor evolution (GAE) hypothesis (Merchant and Honing, 2014) that suggests beat-based timing to be omnipresent in humans but only weakly so or absent in non-human primates.

Behavioral Dynamics of Rhythm and Meter Perception: The Effect of Musical Expertise in Deviance Detection

In two behavioral experiments, we explored effects of long-term musical training on the implicit processing of temporal structures (rhythm, non-rhythm and meter), manipulating deviance detection under different conditions. We used a task that did not require an explicit processing of the temporal aspect of stimuli, as this was irrelevant for the task. In Experiment 1, we investigated whether long-term musical training results in a superior processing of auditory rhythm, and thus boosts the detection of auditory deviants inserted within rhythmic compared to non-rhythmic auditory series. In Experiment 2, we focused on the influence of the metrical positions of a rhythmic series, and we compared musicians and non-musicians’ responses to deviant sounds inserted on strong versus weak metrical positions. We hypothesized that musicians would show enhanced rhythmic processing as compared to non-musicians. Furthermore, we hypothesized that musicians’ expectancy level would differ more across metrical positions compared to non-musicians. In both experiments, musicians were faster and more sensitive than non-musicians. Although both groups were overall faster and showed a higher sensitivity for the detection of deviants in rhythmic compared to non-rhythmic series (Experiment 1), only musicians were faster in the detection of deviants on strong positions compared to weak ones (Experiment 2). While rhythm modulates deviance processing also in non-musicians, specific effects of long-term musical training arise when a refined comparison of hierarchical metrical positions is considered. This suggests that long-term musical training enhances sensitivity to the metrical structure and improves temporal prediction mechanisms, even during implicit processing of meter.

Melodic constructions in Spanish: Metrical structure determines the association properties of intonational tones

This paper explores phrase-length-related alternations in the association of tones to positions in metrical structure in two melodic constructions of Spanish. An imitation-and-completion task eliciting (a) the low–falling–rising contour and (b) the circumflex contour on intonation phrases (IPs) of one, two, and three prosodic words revealed that, although the focus structure and pragmatic context is constant across conditions, phrases containing one prosodic word differ in their nuclear (i.e. final) pitch accents and edge tones from phrases containing more than one prosodic word. For contour (a), short intonation phrases (e.g. [Manolo]IP) were produced with a low accent followed by a high edge tone (L* H% in ToBI notation), whereas longer phrases (e.g. [El hermano de la amiga de Manolo]IP‘Manolo's friend's brother’) had a low accent on the first stressed syllable, a rising accent on the last stressed syllable, and a low edge tone (L* L+H* L%). For contour (b), short phrases were produced with a high–rise (L+H* ¡H%), whereas longer phrases were produced with an initial accentual rise followed by an upstepped rise–fall (L+H* ¡H* L%). These findings imply that the common practice of describing the structure of intonation contours as consisting of a constant nuclear pitch accent and following edge tone is not adequate for modeling Spanish intonation. To capture the observed melodic alternations, we argue for clearer separation between tones and metrical structure, whereby intonational tones do not necessarily have an intrinsic culminative or delimitative function (i.e. as pitch accents or as edge tones). Instead, this function results from melody-specific principles of tonal–metrical association.

Translating Shakespeare’s Sonnets

This paper presents a set of translations for Shakespeare’s sonnets which are expressive of thoughts andemotions on human mortality. The translations, which focus on meaning rather than structure, are based on scholars’ discussions of denotations and connotations. The discussions include how the versification or metrical structure and cultural context of the sonnets affect meaning. This is meant to produce the so-called “equivalent effect” which is explained below.
 References
 Booth, Stephen. An Essay on Shakespeare’s Sonnets. London: Yale UniversityPress, 1969.
 __________________. Shakespeare’s Sonnets. London: Yale University Press, 1977. Callaghan,Dympna. Shakespeare’s Sonnets. Oxford: Blackwell, 2007.
 Oxquarry Books Ltd. Shakespeare’s Sonnets. Accessed December 26, 2016.
 Seymour-Smith, Martin. Shakespeare’s Sonnets. London: Heinneman, 1963.
 Watson, Amanda. “Full Character’d” : Competing Forms of Memory. Ed. MichaelSchoenfeldt. West Sussex: Blackwell, 2010.

Evidence for Metrical Prominence Asymmetries in Medʉmba

Headedness has played a crucial role in the characterization of metrical structure since the earliest proposals for its existence, with definitions of headedness typically relying on the notion of relative syllable prominence: heads are said to bear relatively greater prominence than nonheads. But what counts as prominent for the sake of headedness varies widely across languages, particularly where evidence for stress is weak or absent. The present work seeks to look beyond acoustic evidence for headedness by conceptualizing metrical prominence in terms of its coordinative role in speech timing. Here, we examine timing of metrically-prominent syllables in Medʉmba, a Grassfields Bantu language spoken in Cameroon. Medʉmba has no phonetic evidence of stress, but displays evidence of metrical prominence asymmetries at the word level. We use the speech cycling paradigm (Cummins & Port 1998) to compare results regarding the timing of metrically prominent syllables in Medʉmba with those from previous work on stressed syllables in English and accented syllables in Japanese and Korean, showing that a unified notion of metrical prominence can be applied across languages.

The teaching and learning of L2 English intonation in a distance education environment: TL_ToBI vs. the traditional models

The teaching of intonation to learners of a second language (L2) tends to be an arduous and often neglected task even in specialized phonetic classes. This difficulty generally increases in a distance learning environment where students have to approach prosodic issues in an autonomous way. This paper tests the advantages and disadvantages of using a new model to teach English intonation to Spanish speakers in a self-tuition context, called TL_ToBI (Teaching and Learning ToBI), and compares the benefits of this proposal with the traditional methodologies. Two groups of Spanish students of English phonetics in a distance learning environment took part in this study. Each group was trained with a different methodology: 1) the British School of intonation and 2) TL_ToBI, which involves an adaptation of the ToBI conventions for teaching purposes. The intonation of four sentence types was assessed: declarative, yes-no question, wh-question, and imperative, produced both with neutral and marked readings. The results showed that those speakers trained with TL_ToBI produced more native-like intonation patterns than those instructed with the other model. These findings suggest that a system based on tonal targets and their association to the metrical structure has more benefits for the acquisition of the L2 prosody in a distance learning setting.

El poderoso y su doble. Amis y Amiles en el teatro clásico español

The aim of this article is twofold. First, to analyze two Spanish theatrical versions of the legend of Amis and Amiles; for which purpose we will study La sutil marana de los dos fieles y parescidos amigos Luis y Alejandro y los sucesos de Alejandro y como por su saber vino a ser rey de Egipto (BNE, mss. 15049) and Los pronosticos de Alejandre (BNE, mss. 16064), in order to explore their connection with the 21st chapter of the Seven Sages of Rome. The analysis of the texts’ metrical structure reveals that they were probably written during the last two decades of the 16th century. The second aim is to go deeper into Philip III's education and cultural background by analyzing the friendship between Luis and Alejandro, as well as the use and significances of the mythic theme of the double.

Neural processing of musical meter in musicians and non-musicians

Musical sounds, along with speech, are the most prominent sounds in our daily lives. They are highly dynamic, yet well structured in the temporal domain in a hierarchical manner. The temporal structures enhance the predictability of musical sounds. Western music provides an excellent example: while time intervals between musical notes are highly variable, underlying beats can be realized. The beat-level temporal structure provides a sense of regular pulses. Beats can be further organized into units, giving the percept of alternating strong and weak beats (i.e. metrical structure or meter). Examining neural processing at the meter level offers a unique opportunity to understand how the human brain extracts temporal patterns, predicts future stimuli and optimizes neural resources for processing. The present study addresses two important questions regarding meter processing, using the mismatch negativity (MMN) obtained with electroencephalography (EEG): 1) how tempo (fast vs. slow) and type of metrical structure (duple: two beats per unit vs. triple: three beats per unit) affect the neural processing of metrical structure in non-musically trained individuals, and 2) how early music training modulates the neural processing of metrical structure. Metrical structures were established by patterns of consecutive strong and weak tones (Standard) with occasional violations that disrupted and reset the structure (Deviant). Twenty non-musicians listened passively to these tones while their neural activities were recorded. MMN indexed the neural sensitivity to the meter violations. Results suggested that MMNs were larger for fast tempo and for triple meter conditions. Further, 20 musically trained individuals were tested using the same methods and the results were compared to the non-musicians. While tempo and meter type similarly influenced MMNs in both groups, musicians overall exhibited significantly reduced MMNs, compared to their non-musician counterparts. Further analyses indicated that the reduction was driven by responses to sounds that defined the structure (Standard), not by responses to Deviants. We argue that musicians maintain a more accurate and efficient mental model for metrical structures, which incorporates occasional disruptions using significantly fewer neural resources.

Jaw Displacement and Metrical Structure in Japanese : The Effect of Pitch Accent, Foot Structure, and Phrasal Stress( Articulatory Phonetics: Focus on Japanese)

Jaw Displacement and Metrical Structure in Japanese : The Effect of Pitch Accent, Foot Structure, and Phrasal Stress( Articulatory Phonetics: Focus on Japanese)

Prosody of Dual-focus in German: Interaction between Focus and Phrasing.

This paper studies the prosodic realization of dual-focus in German, that is, two foci in a single sentence, with special consideration of the interaction between focus assignment and phrasing. In a production experiment, dual-focus was compared with its initial, final, and all-new counterparts in sentences with subject NPs and VPs of different lengths. The results showed that there were three different patterns of dual-focus realization: (1) The most frequent one was the two-peak pattern (57.8%), that is, a falling tone on both focused words and compressed and lowered pitch in-between; (2) the second most frequent was the two-phrase realization (23.5%), in which both foci were also realized as a falling tone, but in this case, a high boundary tone was inserted after the subject NP; (3) the least frequent pattern was the hat-pattern (18.7%), consisting of a rising tone on the first focus and a falling tone on the second one while the pitch in-between is kept as a high plateau. This was applied mostly in utterances containing a short subject NP. We interpret these results in terms of optional prosodic phrasing. A sentence with two foci can be realized in one or two intonation phrases, but in both cases, the focus is assigned within the prosodic domain derived from syntax. These results show that Culminativity, the principle requiring a one-to-one correspondence between prosodic domains and their heads, is violable in German. Two equally prominent pitch accents are allowed to co-exist in one intonation phrase. Finally, the metrical structure of dual-focus speaks for a recursive structure of German prosody.

Synchronization to metrical levels in music depends on low-frequency spectral components and tempo.

Previous studies have found relationships between music-induced movement and musical characteristics on more general levels, such as tempo or pulse clarity. This study focused on synchronization abilities to music of finely-varying tempi and varying degrees of low-frequency spectral change/flux. Excerpts from six classic Motown/R&B songs at three different tempos (105, 115, and 130 BPM) were used as stimuli in this experiment. Each was then time-stretched by a factor of 5% with regard to the original tempo, yielding a total of 12 stimuli that were presented to 30 participants. Participants were asked to move along with the stimuli while being recorded with an optical motion capture system. Synchronization analysis was performed relative to the beat and the bar level of the music and four body parts. Results suggest that participants synchronized different body parts to specific metrical levels; in particular, vertical movements of hip and feet were synchronized to the beat level when the music contained large amounts of low-frequency spectral flux and had a slower tempo, while synchronization of head and hands was more tightly coupled to the weak flux stimuli at the bar level. Synchronization was generally more tightly coupled to the slower versions of the same stimuli, while synchronization showed an inverted u-shape effect at the bar level as tempo increased. These results indicate complex relationships between musical characteristics, in particular regarding metrical and temporal structure, and our ability to synchronize and entrain to such musical stimuli.

A musical model of speech rhythm.

. . iambic [is] the verse-form closest to speech. There is evidence of this: we speak iambics in conversation with each other very often. . . .Aristotle in PoeticsMuch work on speech has been driven far more by a desire to classify languages into categories than by the need to elucidate the actual rhythms of spoken utterances. Common approaches to speech focus, for example, on the variability of syllabic durations within utterances (Grabe & Low, 2002) or the proportion of an utterance's duration that is occupied by vowels (Ramus, Nespor, & Mehler, 1999). But these features do not specify actual rhythms-that is, the temporal patterns of syllable onsets within an utterance-and instead reduce whole languages to descriptive statistics. Knowing that English is 40% vocalic (Ramus et al., 1999) indicates little about the timing of syllable onsets within any given English utterance, even though this information may be useful in differentiating English taxonomically from languages having different types of syllable structure.Outside of linguistics, though, representations of sentence rhythms are commonplace, and it is unclear why such representations have not had a larger impact on linguistic theories. Poetic verse, song, Shakespearean dialogue, and rap are all based on musical notions of the periodicity of syllable onsets. Consider the rhythmic transcription of the text of the children's song Twinkle Twinkle shown in Figure 1a. The is organized as a two-beat cycle alternating between strong and weak beats. The relative onset-time and relative duration of every syllable in the sentence is specified, hence making this a true representation of a rhythm. Next, the stressed syllables of the disyllabic words fall on the strong beats of the two-beat cycle (i.e., the downbeats), whereas the unstressed syllables fall on the weak beats. Finally, we see that even silence is specified in this transcription in the form of the rest that sits in between star and How, in this case indicating a sentence break.Regardless of the fact that Twinkle Twinkle is a poetic form of speech, its transcription effectively captures the basic elements of what a model of speech should describe: (a) it specifies a unit of rhythm, in this case the two-beat metrical units that make up each measure of the transcription; (b) it specifies the relative onset-time and relative duration of every syllable in the sentence; and (c) it represents not only the duration but the weight (i.e., stress) of each syllable in the sentence, such that prominent syllables fall on strong beats. Each of these three elements has been analyzed in isolation in various models of speech rhythm, but they have rarely been synthesized into a unified model. These three elements have been analyzed, respectively, in isochrony models, metrics, and metrical phonology. We briefly review these three traditions in phonology before mentioning the only integrated account that we know of, namely Joshua Steele's 1775, treatise An Essay Toward Establishing the Melody and Measure of Speech to be Expressed and Perpetuated by Peculiar Symbols. In our study, we report a test of a critical prediction of a musical model of speech, namely, that the production of time intervals between stressed syllables (here called groups) is based on a music-like representation of metrical structure. In particular, the of speech can serve to stabilize the timing of prominence groups when the timing of individual syllables varies. At the same time, speech (like music) can feature changes in meter that lead to commensurate changes in the timing of prominence groups.Isochrony ModelsThe first issue for speech relates to specifying a unit of rhythm. Lloyd James (1940, quoted in Pike, 1945) contrasted languages having a similar to a machine gun with those having a similar to Morse code. Pike (1945) classified such languages as syllable-timed and stress-timed, respectively, a categorization that is often referred to as the rhythm class hypothesis (Abercrombie, 1967; Grabe & Low, 2002). …

(1,1)-Tensor sphere bundle of Cheeger\u2013Gromoll type

We construct a metrical framed f(3,-1)-structure on the (1, 1)-tensor bundle of a Riemannian manifold equipped with a Cheeger–Gromoll type metric and by restricting this structure to the (1, 1)-tensor sphere bundle, we obtain an almost metrical paracontact structure on the (1, 1)-tensor sphere bundle. Moreover, we show that the (1, 1)-tensor sphere bundles endowed with the induced metric are never space forms.

Dynamical Constants and Time Universals: A First Step toward a Metrical Definition of Ordered and Abnormal Cognition.

From the point of view of the cognitive dynamicist the organization of brain circuitry into assemblies defined by their synchrony at particular (and precise) oscillation frequencies is important for the correct correlation of all independent cortical responses to the different aspects of a given complex thought or object. From the point of view of anyone operating complex mechanical systems, i.e., those comprising independent components that are required to interact precisely in time, it follows that the precise timing of such a system is essential – not only essential but measurable, and scalable. It must also be reliable over observations to bring about consistent behavior, whatever that behavior is. The catastrophic consequence of an absence of such precision, for instance that required to govern the interference engine in many automobiles, is indicative of how important timing is for the function of dynamical systems at all levels of operation. The dynamics and temporal considerations combined indicate that it is necessary to consider the operating characteristic of any dynamical, cognitive brain system in terms, superficially at least, of oscillation frequencies. These may, themselves, be forensic of an underlying time-related taxonomy. Currently there are only two sets of relevant and necessarily systematic observations in this field: one of these reports the precise dynamical structure of the perceptual systems engaged in dynamical binding across form and time; the second, derived both empirically from perceptual performance data, as well as obtained from theoretical models, demonstrates a timing taxonomy related to a fundamental operator referred to as the time quantum. In this contribution both sets of theory and observations are reviewed and compared for their predictive consistency. Conclusions about direct comparability are discussed for both theories of cognitive dynamics and time quantum models. Finally, a brief review of some experimental data measuring sensitivity to visual information presented to the visual blind field (blindsight), as well as from studies of temporal processing in autism and schizophrenia, indicates that an understanding of a precise and metrical dynamic structure may be very important for an operational understanding of perception as well as more general cognitive function in psychopathology.

Generating Time: Rhythmic Perception, Prediction and Production with Recurrent Neural Networks

In the quest for a convincing musical agent that performs in real time alongside human performers, the issues surrounding expressively timed rhythm must be addressed. Current beat tracking methods are not sufficient to follow rhythms automatically when dealing with varying tempo and expressive timing. In the generation of rhythm, some existing interactive systems ignore the pulse entirely, or fix a tempo after some time spent listening to input. Since music unfolds in time, we take the view that musical timing needs to be at the core of a music generation system. Our research explores a connectionist machine learning approach to expressive rhythm generation, based on cognitive and neurological models. Two neural network models are combined within one integrated system. A Gradient Frequency Neural Network (GFNN) models the perception of periodicities by resonating nonlinearly with the musical input, creating a hierarchy of strong and weak oscillations that relate to the metrical structure. A Long Short-term Memory Recurrent Neural Network (LSTM) models longer-term temporal relations based on the GFNN output. The output of the system is a prediction of when in time the next rhythmic event is likely to occur. These predictions can be used to produce new rhythms, forming a generative model. We have trained the system on a dataset of expressively performed piano solos and evaluated its ability to accurately predict rhythmic events. Based on the encouraging results, we conclude that the GFNN-LSTM model has great potential to add the ability to follow and generate expressive rhythmic structures to real-time interactive systems