Pairwise Variability Index Research Articles

PROSODIC TRANSFER IN LEARNER AND CONTACT VARIETIES

A remarkable example of Spanish-Italian contact is the Spanish variety spoken in Buenos Aires (Porteño), which is said to be prosodically “Italianized” due to migration-induced contact. The change in Porteño prosody has been interpreted as a result of transfer from the first language (L1) that occurred when Italian immigrants learned Spanish as a second language (L2; McMahon, 2004). This article aims to examine if and to what extent prosodic features that are typical of Italian show up in Porteño and in L2 Castilian Spanish produced by Italian native speakers. Specifically, we investigated speech rhythm and the realization of yes-no questions in Porteño and L2 Castilian Spanish in comparison to Italian and L1 Castilian Spanish. We hypothesized that Italian, Porteño, and L2 Castilian Spanish would exhibit similar rhythm patterns, showing high values for the percentage of vocalic material, the variation coefficient of vocalic intervals, and the speech-rate-normalized pairwise variability index for vowels as well as high frequencies of rising prenuclear accents, with the peak located at the end of the syllable (L+H*) and falling final contours in yes-no questions, in contrast to Castilian Spanish. The results confirm our predictions for speech rhythm but not entirely for the intonation of yes-no questions.

An acoustic measure of lexical stress differentiates aphasia and aphasia plus apraxia of speech after stroke

Background: Apraxia of Speech (AOS) is partly characterised by impaired production of prosody in words and sentences. Identification of dysprosody is based on perceptual judgements of clinicians, with limited literature on potential quantitative objective measures.Aims: This study investigated whether an acoustic measure quantifying degree of lexical stress contrastiveness in three syllable words, produced in isolation and in a carrier sentence, differentiated individuals with AOS with/without aphasia (AOS), aphasia only (APH), and healthy controls (CTL).Methods & Procedures: Eight individuals with aphasia, nine with AOS plus aphasia and 8 age-matched control participants named pictures of strong–weak and weak–strong polysyllabic words in isolation and in a declarative carrier sentence. Pairwise Variability Indices (PVI) were used to measure the normalised relative vowel duration and peak intensity over the first two syllables of the polysyllabic words.Outcomes & Results: Individuals with aphasia performed similarly to control participants in all conditions. AOS participants demonstrated significantly lower PVI_vowel duration values for words with weak–strong stress produced in the sentence condition only, compared to controls and individuals with aphasia. This was primarily due to disproportionately long vowels in the word-initial weak syllable for AOS participants. There was no difference among groups on PVI_intensity.Conclusions: The finding of reduced lexical stress contrastiveness for weak–strong words in sentences for individuals with mild to moderate–severe AOS is consistent with the perceptual diagnostic feature of equal stress in AOS. Findings provide support for use of the objective PVI_vowel duration measure to help differentiate individuals with AOS (with/without aphasia), from those with aphasia only. Future research is warranted to explore the utility of this acoustic measure, and others, for reliable diagnosis of AOS.

Pattern Recognition in Cyclic and Discrete Skills Performance from Inertial Measurement Units

The aim of this study is to compare and validate an Inertial Measurement Unit (IMU) relative to an optic system, and to propose methods for pattern recognition to capture behavioural dynamics during sport performance. IMU validation was conducted by comparing the motions of the two arms of a compass, which was equipped with IMUs and reflective landmarks detected by a multi-camera system. Spearman's rank correlation tests showed good correlations between the IMU and multi-camera system, especially when the angles were normalized. Bland-Altman plot, root mean square and the normalized pairwise variability index showed low differences between the two systems, confirming the good accuracy levels of the IMUs. Regarding pattern recognition, joint angle and limb orientation was respectively studied for 25 m during breaststroke swimming and 10 m of indoor rock climbing in athletes of various skill levels. Pattern recognition was also conducted on a macroscopic parameter that captured inter-limb coordination. IMUs revealed the potential to assess movement and coordination variability between and within individuals from joint angle measures in swimming and limb orientation time-series data in climbing.

An Empirical Study of Historical Patterns in Musical Rhythm

This paper introduces a new approach for the historical study of musical rhythm based on an empirical measure of rhythm known as the nPVI (‘normalized pairwise variability index’). The nPVI is an equation that measures the degree of durational contrast between successive events in a sequence. While the nPVI is increasingly used for comparative studies of rhythm in music and language, we show that it can also be used for historical research. A historical analysis of musical nPVI values from German/Austrian and Italian instrumental classical music between ∼1600-1900 reveals different patterns in the two cultures: German/Austrian music shows a steady increase in nPVI values over this period, while Italian music shows no salient increase. These patterns are discussed in light of the idea (from historical musicology) that the influence of Italian music on German music began to wane in the second half of the 1700s due to a rise of musical nationalism in Germany. The nPVI data prove to be consistent with this idea, illustrating how nPVI analysis can reveal patterns that enrich and inform historical research.

Emotional Communication in Speech and Music: The Role of Melodic and Rhythmic Contrasts

Many acoustic features convey emotion similarly in speech and music. Researchers have established that acoustic features such as pitch height, tempo, and intensity carry important emotional information in both domains. In this investigation, we examined the emotional significance of melodic and rhythmic contrasts between successive syllables or tones in speech and music, referred to as Melodic Interval Variability (MIV) and the normalized Pairwise Variability Index (nPVI). The spoken stimuli were 96 tokens expressing the emotions of irritation, fear, happiness, sadness, tenderness, or no emotion. The music stimuli were 96 phrases, played with or without performance expression and composed with the intention of communicating the same emotions. Results showed that nPVI, but not MIV, operates similarly in music and speech. Spoken stimuli, but not musical stimuli, were characterized by changes in MIV as a function of intended emotion. The results suggest that these measures may signal emotional intentions differently in speech and music.

Acoustic correlates of rhythm in New Zealand English: A diachronic study

AbstractThis paper reports on a large-scale diachronic investigation into the timing of New Zealand English (NZE), which points to changes in its rhythmic structure. The Pairwise Variability Index (PVI) was used to measure the mean variation in duration, intensity, and pitch of successive vowels in the speech of over 500 New Zealanders, born between 1851 and 1988. Normalized vocalic PVIs for duration have reduced over time, after allowing for changes in speech rate, supporting existing findings that stressed and unstressed vowels are less differentiated by duration in modern NZE than in other varieties of English. Rhythmically, syllable duration may be playing a reduced role in signalling prominence in NZE. This is supported by the finding that there have been contemporaneous changes in pitch and intensity variation. We discuss external and internal influences on the timing of NZE, including contact with Māori, the emergence of Māori English, and diachronic vowel shift.

An investigation of speech rhythm in London English

Recent work on London English has found innovation in inner city areas, most likely as the outcome of dialect contact. These innovations are shared by speakers of different ethnic backgrounds, and have been identified as features of Multicultural London English (MLE). This study examines whether syllable-timing is a feature of MLE, as work on rhythm shows that dialect and language contact may lead to varieties of English becoming more syllable-timed. Narratives as told by teenagers of different ethnic backgrounds and elderly speakers were segmented by forced phonemic alignment and measurements of vocalic normalized Pairwise Variability Index (nPVI), as an indicator of rhythmic patterns, were calculated. The results revealed that young speakers of non-Anglo background were significantly more syllable-timed than young Anglo speakers and the inner-London speakers were more syllable timed than the outer London speakers. Additionally, there was a correlation between articulation rate and nPVI for the non-Anglo speakers: speakers with a high vocalic articulation rate were more syllable-timed. Changes in the duration of particular diphthongs and schwa may have influenced the overall speech rhythm. The relatively low nPVI for all speaker groups may also indicate London's status as a center of linguistic innovation due to long-standing migration.

Perceptually Informed Quantification of Speech Rhythm in Pairwise Variability Indices

Two previous experiments demonstrated that f0 and duration are interdependent in the perception of rhythmic groups in speech and sentence rhythmicality, and that the relative weighting of tonal and durational cues depends on listeners’ native language. The listeners were native speakers of Swiss German, Swiss French, or Metropolitan French (i.e. from France). The experiment reported here investigates a means of applying this perceptual finding to production data from these three languages, to make a rhythm metric, the Pairwise Variability Index (PVI), perceptually informed. The relative weighting that an appropriate duration and an appropriate f0 contributed to listeners’ rhythmicality judgements is calculated, and these language-specific weighting values are incorporated into combined durational- tonal PVIs, to quantify rhythm in the three languages. The results demonstrate that Swiss German and Swiss/Metropolitan French are distinct according to classic durational PVIs, but more similar according to PVIs which are acoustically multidimensional and language-specifically weighted. It is concluded that rhythm produced by speakers, when quantified to account for the acoustic multidimensionality and language-specificity of rhythm perceived by listeners, may be less cross-linguistically divergent than durational rhythm metrics suggest. An evaluation of these language-specifically weighted PVIs concludes that if rhythm metrics remain in use, they should link rhythm perception with rhythm production.

Acoustic correlates of spanish speech rhythms

This paper describes a study of the acoustic correlates of speech rhythms of Hispanic Bilinguals living in California and Mexican Monolinguals living in Mexico City in order to study the effect of bilingualism on language, especially on rhythm classes, and the reliability of acoustic correlates in distinguishing these classes. This study addresses stress-timing versus syllable-timing as described in Pike's pioneering work (1945). Ten monolingual speakers from Mexico and ten bilingual Spanish–English speakers born and raised in California to Mexican parents were recorded speaking spontaneously. Fifty vowel durations per speaker were collected from phrases in these recordings and explored statistically and graphically with R.2.12.2 (R Development Core Team, 2011) in order to determine the reliability of various acoustical correlates of language rhythms in differentiating speech rhythms between varieties of Spanish. Specifically the Pairwise Variability Index, introduced by Low and Grabe (1995), and interval measures, such as the standard deviation and normalized standard deviation of vowel durations, were explored. The effects of word frequencies, as determined by relevant files from the Corpus del Espa'ol (Davies, 2002), were also considered in the analysis of the data. [Work supported by a grant for the University of California Institute for Mexico and the United States (UC Mexus).]

Rhythmic Refinements to the nPVI Measure: A Reanalysis of Patel & Daniele (2003a)

the normalized pairwise variability index (npvi) , originally developed for the analysis of speech prosody, has been shown to be a useful tool in the analysis of the rhythmic variability present in individual melodies and melodic corpuses (Patel & Daniele, 2003a; Huron & Ollen, 2003; Patel, Iverson, & Rosenberg, 2006). Here we suggest a number of rhythmic refinements for the application of the nPVI in musical contexts. These include (a) applying the nPVI metric to higher levels of rhythmic structure, (b) taking metrical structure (duple versus triple) into account, and (c) using alternative codings for surface durations. A reanalysis of the data from Patel & Daniele (2003a) is given as a demonstration of the utility of these refinements for the analysis of musical styles and repertoires; other possible refinements are discussed.

An Acoustic Study of the Relationships Among Neurologic Disease, Dysarthria Type, and Severity of Dysarthria

This study examined acoustic predictors of speech intelligibility in speakers with several types of dysarthria secondary to different diseases and conducted classification analysis solely by acoustic measures according to 3 variables (disease, speech severity, and dysarthria type). Speech recordings from 107 speakers with dysarthria due to Parkinson's disease, stroke, traumatic brain injury, and multiple system atrophy were used for acoustic analysis and for perceptual judgment of speech intelligibility. Acoustic analysis included 8 segmental/suprasegmental features: 2nd formant frequency slope, articulation rate, voiceless interval duration, 1st moment analysis for fricatives, vowel space, F0, intensity range, and Pairwise Variability Index. The results showed that (a) acoustic predictors of speech intelligibility differed slightly across diseases and (b) classification accuracy by dysarthria type was typically worse than by disease type or severity. These findings were discussed with respect to (a) the relationship between acoustic characteristics and speech intelligibility and (b) dysarthria classification.

The acoustic reality of the Kachruvian circles: a rhythmic perspective

ABSTRACT: This paper investigates whether the rhythmic properties of varieties of English found in each of the concentric circles of Kachru's model can, in any way, be elucidated by the ‘Three Circles’ model. A measurement and comparison of the rhythm of three varieties of English: British English (from the Inner Circle), Singapore English (from the Outer Circle) and Mainland Chinese English (from the Expanding Circle) is done from recordings made of one subject from each variety reading The North Wind and the Sun passage. Measurements are made of successive vowel durations and the pairwise variability index (PVI) developed by Low, Grabe, and Nolan is calculated in an attempt to capture the rhythmic properties of the three varieties. The PVI has been shown to effectively capture the broad rhythmic typology between stress-based and syllable-based varieties of English. In particular, this paper examines whether it is the case that Mainland Chinese English (a norm-dependent variety) differs significantly in the rhythmic domain from Singapore English (a norm-developing variety) and be proven to be statistically similar to British English (a norm-providing variety).

The strength of foreign accent in Czech English under adverse listening conditions

The study connects two major topics in current speech research: foreign accentedness and speech in adverse conditions. We parallel the research in intelligibility of non-native speech, but instead of linguistic unit recognition we focus on the perception of the foreign accent strength. First, the question of type and degree of perceptual deficiencies occurring along with certain types of signal degradation is tackled. Second, we measure correlations between the accent ratings and certain candidate phenomena that may influence them, e.g., articulation rate, temporal patterning, contrasts in sound pressure levels on selected syllables and F0 variation. The impacts of different types of signal degradation help to estimate the role of segmental/suprasegmental information in assessments of foreignness in Czech English. The full appreciation of the strength of foreign accent is apparently not possible without fine phonetic detail on the segmental level. However, certain suprasegmental features of foreignness are robust enough to manifest at severe levels of signal degradation. Pairwise variability indices of vowel durations and variation in F0 tracks seem to guide the listener even better in the degraded than in the ‘clean’ speech signal.

Comparison of rhythm in musical scores and performances as measured with the pairwise variability index

This paper tests two hypotheses: (1) the normalized Pairwise Variability Index (nPVI) values computed on the basis of recorded performances may be higher than the nPVI values computed for the same works as musical scores, and (2) the musical nPVI values for different composers may vary substantially within one culture even within a short time-span. In Study 1, samples from the vocal works of four Estonian composers, Artur Kapp (1878–1952), Mart Saar (1882–1963), Eduard Oja (1905–1950) and Eduard Tubin (1905–1982) were used for calculation of nPVI on the basis of both scores and performances. nPVI values for performed music were higher than those for scores but the differences were rarely statistically significant. In Study 2, larger corpora of scores by three Estonian composers: Saar, Tubin, and Veljo Tormis (born 1930) were analyzed. Songs by Tormis had significantly lower nPVI values than those by Saar and Tubin. Our results imply that calculation of nPVI values in music may rely either on a score or on a performance, the results being not significantly different from each other. The results also show that there may be significant differences in rhythmic contrast between the works of composers from one culture created only a few decades apart, and that nPVI values may not only increase but also decrease for compositions created later in time.

The Role of Meter in Compositional Style in 19th Century French and German Art Song

This study extends prior research on the influence of linguistic rhythm on musical rhythm to 19th century French and German art songs. Results indicate that the measurement of rhythmic variability used in prior studies, the nPVI, or normalized Pairwise Variability Index, may be of use in studying individual compositional style even when a significant correlation with spoken language characteristics is not present in the repertoire. By modifying and focusing the results of the nPVI, and studying the relationship between rhythmic variability and notated meter, it is possible to determine musically meaningful information about individual composer's rhythmic characteristics.

Thai English

We explore two aspects of English spoken by native speakers of Thai: rhythm and the vowel system, and compare each to the substrate language Thai, to target varieties of English, and to two New Englishes in Asia. Data was collected from a group of Thai speakers who participated in an interview in English, and who read a Thai paragraph, and English words, sentences and a paragraph. For rhythm, we measured the “Pairwise Variability Index” (nPVI, Grabe and Low 2002) and the proportion of time in an utterance devoted to vowels (%V, Ramus, Nespor and Mehler 1999) of Thai read speech, and English spontaneous and read speech. We find that the English of Thai speakers had stress-timed values of high nPVI, like Thai and British English (BrE), and low %V, like BrE but not Thai. Neither measure of rhythm resembled New Englishes’ more syllable-timed lower nPVI and high %V. The vowel system of Thai English revealed transfers of both quality and quantity from the substrate, resulting in a system distinct from British, American, and New Englishes.

The Pairwise Variability Index and Coexisting Rhythms in Language

The Pairwise Variability Index (PVI) has been widely used as a metric for quan-tifying rhythm in languages, often with a view to placing them on a continuum between notional categories of stress-timing and syllable-timing. We review the history of and rationale for the PVI, and point out three potential anomalies in the way the PVI has been applied. Following up one of these we apply the PVI to the level of the foot, and argue that stress-timing and syllable-timing are not points at either end of a continuum but orthogonal dimensions, so that a language can be (for instance) both syllable-timed and stress-timed. Results from Estonian, English, Mexican Spanish, and Castilian Spanish are presented which give some support for this view.

Do Rhythm Measures Reflect Perceived Rhythm?

In a production study, Bulgarian, English and German verses with regular poetic metrical metres of different types and elicited prose utterances with varied accentual patterns are produced in textual and iterative (dada) form and measured at syllable level according to the pairwise variability index (PVI) principle. Systematic differences in PVI values show that the measure is sensitive to metrical differences. But variations for utterances with the same metrical structure and comparable measures for accentually different utterances show the measure to be insensitive to the temporal distribution of accents. A perceptual experiment with Bulgarian, English and German subjects confirms the hypothesis that the perceived strength of rhythmicity in a line of verse is determined not only by its temporal structure, but also by other acoustic properties, most clearly by F₀ change within the metrical foot.

The Relative Importance of Rhythm and Intonation for the Perception of New Zealand English Dialects

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On the reliability of rhythm metrics.

In the past decade or so, various metrics of vocalic and consonantal variability have been used to quantify linguistic rhythm, often yielding disparate results. The reliability of several such metrics (percentage of vocalic intervals and consonantal standard deviation, pairwise variability indices, and variation coefficient) was tested using materials from stress-timed English and German, syllable-timed Spanish and Italian, Korean, an unclassified language, and Greek, which has resisted classification. The materials for each language were divided into three subsets: an uncontrolled subset of sentences excerpted from a representative author of each language, a subset exhibiting as much as possible “stress-timing” properties (complex syllable structure and extensive vocalic variability), and a subset exhibiting as much as possible “syllable-timing” properties (simple syllable structure and limited vocalic variability). The results suggest that rhythmic scores can be severely affected by the choice of materials, especially in languages such as Italian, in which it is easy to avoid or accentuate variability (e.g., by excluding or including geminates). Variation coefficient scores were the most resistant to the manipulation of materials but failed to show statistical differences across most of the languages examined. The overall results cast doubt on the reliability of metric scores as indicators of timing and linguistic rhythm.