Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios

Rhythm is fundamental in many physical and biological systems. Rhythm is relevant to a broad range of phenomena across different fields, including animal bioacoustics, speech sciences, and music cognition. As a result, the interest in developing consistent quantitative measures for cross-disciplinar...

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Main Authors: Yannick Jadoul, Francesca D’Orazio, Vesta Eleuteri, Jelle van der Werff, Tommaso Tufarelli, Marco Gamba, Teresa Raimondi, Andrea Ravignani
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Vibration
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Online Access:https://www.mdpi.com/2571-631X/8/2/12
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author Yannick Jadoul
Francesca D’Orazio
Vesta Eleuteri
Jelle van der Werff
Tommaso Tufarelli
Marco Gamba
Teresa Raimondi
Andrea Ravignani
author_facet Yannick Jadoul
Francesca D’Orazio
Vesta Eleuteri
Jelle van der Werff
Tommaso Tufarelli
Marco Gamba
Teresa Raimondi
Andrea Ravignani
author_sort Yannick Jadoul
collection DOAJ
description Rhythm is fundamental in many physical and biological systems. Rhythm is relevant to a broad range of phenomena across different fields, including animal bioacoustics, speech sciences, and music cognition. As a result, the interest in developing consistent quantitative measures for cross-disciplinary rhythmic analysis is growing. Two quantitative measures that can be directly applied to any temporal structure are the normalized pairwise variability index (nPVI) and rhythm ratios (r<sub>k</sub>). The nPVI summarizes the overall isochrony of a sequence, i.e., how regularly spaced a sequence’s events are, as a single value. Meanwhile, r<sub>k</sub> quantifies ratios between a sequence’s adjacent intervals and is often used for identifying rhythmic categories. Here, we show that these two rhythmic measures are fundamentally connected: the nPVI is a summary static of the r<sub>k</sub> values of a temporal sequence. This result offers a deeper understanding of how these measures are applied. It also opens the door for creating novel, custom measures to quantify rhythmic patterns based on a sequence’s r<sub>k</sub> distribution and compare rhythmic patterns across different domains. The explicit connection between nPVI and r<sub>k</sub> is one further step towards a common quantitative toolkit for rhythm research across disciplines.
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spelling doaj-art-b0af4b3a0f4b440aba25c54ed07966c42025-08-20T03:26:56ZengMDPI AGVibration2571-631X2025-03-01821210.3390/vibration8020012Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm RatiosYannick Jadoul0Francesca D’Orazio1Vesta Eleuteri2Jelle van der Werff3Tommaso Tufarelli4Marco Gamba5Teresa Raimondi6Andrea Ravignani7Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, ItalyDepartment of Human Neurosciences, Sapienza University of Rome, 00185 Rome, ItalyDepartment of Behavioral and Cognitive Biology, University of Vienna, 1030 Vienna, AustriaDepartment of Human Neurosciences, Sapienza University of Rome, 00185 Rome, ItalyIndependent Researcher, Beeston NG9, UKDepartment of Life Sciences and Systems Biology, University of Turin, 10124 Turin, ItalyDepartment of Human Neurosciences, Sapienza University of Rome, 00185 Rome, ItalyDepartment of Human Neurosciences, Sapienza University of Rome, 00185 Rome, ItalyRhythm is fundamental in many physical and biological systems. Rhythm is relevant to a broad range of phenomena across different fields, including animal bioacoustics, speech sciences, and music cognition. As a result, the interest in developing consistent quantitative measures for cross-disciplinary rhythmic analysis is growing. Two quantitative measures that can be directly applied to any temporal structure are the normalized pairwise variability index (nPVI) and rhythm ratios (r<sub>k</sub>). The nPVI summarizes the overall isochrony of a sequence, i.e., how regularly spaced a sequence’s events are, as a single value. Meanwhile, r<sub>k</sub> quantifies ratios between a sequence’s adjacent intervals and is often used for identifying rhythmic categories. Here, we show that these two rhythmic measures are fundamentally connected: the nPVI is a summary static of the r<sub>k</sub> values of a temporal sequence. This result offers a deeper understanding of how these measures are applied. It also opens the door for creating novel, custom measures to quantify rhythmic patterns based on a sequence’s r<sub>k</sub> distribution and compare rhythmic patterns across different domains. The explicit connection between nPVI and r<sub>k</sub> is one further step towards a common quantitative toolkit for rhythm research across disciplines.https://www.mdpi.com/2571-631X/8/2/12nPVIrhythmic measuresbioacousticsvocalizationtimingtemporal sequences
spellingShingle Yannick Jadoul
Francesca D’Orazio
Vesta Eleuteri
Jelle van der Werff
Tommaso Tufarelli
Marco Gamba
Teresa Raimondi
Andrea Ravignani
Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios
Vibration
nPVI
rhythmic measures
bioacoustics
vocalization
timing
temporal sequences
title Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios
title_full Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios
title_fullStr Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios
title_full_unstemmed Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios
title_short Rhythmic Analysis in Animal Communication, Speech, and Music: The Normalized Pairwise Variability Index Is a Summary Statistic of Rhythm Ratios
title_sort rhythmic analysis in animal communication speech and music the normalized pairwise variability index is a summary statistic of rhythm ratios
topic nPVI
rhythmic measures
bioacoustics
vocalization
timing
temporal sequences
url https://www.mdpi.com/2571-631X/8/2/12
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