The psychological reality of rhythm classes: Perceptual studies

Linguists have traditionally classified languages into three rhythm classes, namely stress-timed, syllable-timed and mora-timed languages. However, this classification has remained controversial for various reasons: the search for reliable acoustic cues to the different rhythm types has long remained elusive; some languages are claimed to belong to none of the three classes; and few perceptual studies has bolstered the notion. We have previously proposed an acoustic/phonetic model of the different types of linguistic rhythm, and of their categorisation as such by listeners. Here, we present perceptual experiments that directly test the notion of rhythm classes, our model's predictions, and the question of intermediate languages. Language discrimination experiments were run using a speech resynthesis technique to ensure that only rhythmic cues were available to the subjects. Languages investigated were English, Dutch, Spanish, Catalan and Polish. Our results are consistent with the idea that English and Dutch are stress-timed, Spanish and Catalan are syllable-timed, but Polish seems to be different from any other language studied and thus may constitute a new rhythm class. We propose that perceptual studies tapping the ability to discriminate languages' rhythm are the proper way to generate more empirical data relevant to rhythm typology

Interrupt Timed Automata: verification and expressiveness

We introduce the class of Interrupt Timed Automata (ITA), a subclass of hybrid automata well suited to the description of timed multi-task systems with interruptions in a single processor environment. While the reachability problem is undecidable for hybrid automata we show that it is decidable for ITA. More precisely we prove that the untimed language of an ITA is regular, by building a finite automaton as a generalized class graph. We then establish that the reachability problem for ITA is in NEXPTIME and in PTIME when the number of clocks is fixed. To prove the first result, we define a subclass ITA- of ITA, and show that (1) any ITA can be reduced to a language-equivalent automaton in ITA- and (2) the reachability problem in this subclass is in NEXPTIME (without any class graph). In the next step, we investigate the verification of real time properties over ITA. We prove that model checking SCL, a fragment of a timed linear time logic, is undecidable. On the other hand, we give model checking procedures for two fragments of timed branching time logic. We also compare the expressive power of classical timed automata and ITA and prove that the corresponding families of accepted languages are incomparable. The result also holds for languages accepted by controlled real-time automata (CRTA), that extend timed automata. We finally combine ITA with CRTA, in a model which encompasses both classes and show that the reachability problem is still decidable. Additionally we show that the languages of ITA are neither closed under complementation nor under intersection

Active Learning of Deterministic Timed Automata with Myhill-Nerode Style Characterization

We present an algorithm to learn a deterministic timed automaton (DTA) via membership and equivalence queries. Our algorithm is an extension of the L* algorithm with a Myhill-Nerode style characterization of recognizable timed languages, which is the class of timed languages recognizable by DTAs. We first characterize the recognizable timed languages with a Nerode-style congruence. Using it, we give an algorithm with a smart teacher answering symbolic membership queries in addition to membership and equivalence queries. With a symbolic membership query, one can ask the membership of a certain set of timed words at one time. We prove that for any recognizable timed language, our learning algorithm returns a DTA recognizing it. We show how to answer a symbolic membership query with finitely many membership queries. We also show that our learning algorithm requires a polynomial number of queries with a smart teacher and an exponential number of queries with a normal teacher. We applied our algorithm to various benchmarks and confirmed its effectiveness with a normal teacher

Active Learning of Deterministic Timed Automata with Myhill-Nerode Style Characterization

Part of the Lecture Notes in Computer Science book series (LNCS, volume 13964)35th International Conference, CAV 2023, Paris, France, July 17–22, 2023We present an algorithm to learn a deterministic timed automaton (DTA) via membership and equivalence queries. Our algorithm is an extension of the L* algorithm with a Myhill-Nerode style characterization of recognizable timed languages, which is the class of timed languages recognizable by DTAs. We first characterize the recognizable timed languages with a Nerode-style congruence. Using it, we give an algorithm with a smart teacher answering symbolic membership queries in addition to membership and equivalence queries. With a symbolic membership query, one can ask the membership of a certain set of timed words at one time. We prove that for any recognizable timed language, our learning algorithm returns a DTA recognizing it. We show how to answer a symbolic membership query with finitely many membership queries. We also show that our learning algorithm requires a polynomial number of queries with a smart teacher and an exponential number of queries with a normal teacher. We applied our algorithm to various benchmarks and confirmed its effectiveness with a normal teacher

Model checking time-constrained scenario-based specifications

We consider the problem of model checking message-passing systems with real-time requirements. As behavioural specifications, we use message sequence charts (MSCs) annotated with timing constraints. Our system model is a network of communicating finite state machines with local clocks, whose global behaviour can be regarded as a timed automaton. Our goal is to verify that all timed behaviours exhibited by the system conform to the timing constraints imposed by the specification. In general, this corresponds to checking inclusion for timed languages, which is an undecidable problem even for timed regular languages. However, we show that we can translate regular collections of time-constrained MSCs into a special class of event-clock automata that can be determinized and complemented, thus permitting an algorithmic solution to the model checking problem

Music skills of Spanish-speaking children with developmental language disorder

Background: According to temporal sampling theory, deficits in rhythm processing contribute to both language and music difficulties in children with developmental language disorder (DLD). Evidence for this proposition is derived mainly from studies conducted in stress-timed languages, but the results may differ in languages with different rhythm features (e.g., syllable-timed languages).Aims: This research aimed to study a previously unexamined topic, namely, the music skills of children with DLD who speak Spanish (a syllable-timed language), and to analyze the possible relationships between the language and music skills of these children.Methods and Procedures: Two groups of 18 Spanish-speaking children with DLD and 19 typicallydeveloping peers matched for chronological age completed a set of language tests. Their rhythm discrimination, melody discrimination and music memory skills were also assessed. Outcomes and Results: Children with DLD exhibited significantly lower performance than their typically-developing peers on all three music subtests. Music and language skills were significantly related in both groups.Conclusions and Implications: The results suggest that similar music difficulties may be found in children with DLD whether they speak stress-timed or syllable-timed languages. The relationships found between music and language skills may pave the way for the design of possible language intervention programs based on music stimuli.Department of Developmental and Educational Psychology of UNE

Speech rhythm: a metaphor?

Is speech rhythmic? In the absence of evidence for a traditional view that languages strive to coordinate either syllables or stress-feet with regular time intervals, we consider the alternative that languages exhibit contrastive rhythm subsisting merely in the alternation of stronger and weaker elements. This is initially plausible, particularly for languages with a steep ‘prominence gradient’, i.e. a large disparity between stronger and weaker elements; but we point out that alternation is poorly achieved even by a ‘stress-timed’ language such as English, and, historically, languages have conspicuously failed to adopt simple phonological remedies that would ensure alternation. Languages seem more concerned to allow ‘syntagmatic contrast’ between successive units and to use durational effects to support linguistic functions than to facilitate rhythm. Furthermore, some languages (e.g. Tamil, Korean) lack the lexical prominence which would most straightforwardly underpin prominence alternation. We conclude that speech is not incontestibly rhythmic, and may even be antirhythmic. However, its linguistic structure and patterning allow the metaphorical extension of rhythm in varying degrees and in different ways depending on the language, and that it is this analogical process which allows speech to be matched to external rhythms