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The role of density, variability,

and syncopation in perceived rhythmic complexity.

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Konrad van Heukelom & Dr. Leigh VanHandel

Faculty of Arts, UBC School of Music

Study Motivations & Goals

This study was designed to confirm results from VanHandel 2024, and to provide additional data to help verify and explain the unexpected interaction between density and variability.

Results

Introduction

Prior research has demonstrated that factors contributing to the perception of rhythmic complexity include:

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    • Tempo: Speed, measured in milliseconds inter-onset-interval (ms IOI). (Smaller numbers indicate faster tempos; larger indicate slower.)
    • Density: The number of events per unit of time.
    • Syncopation: The number and type of off-beat events.
    • Variability: Differences in successive note duration, measured using nPVI.

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Tempo is the strongest factor overall; as tempo gets faster, perceived complexity increases. Tempo interacts in different ways with the factors of density, syncopation, and variability.

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An unexpected finding in VanHandel (2024) was that the strength of the effect of variability is also highly dependent on density; the effect was strongest when the rhythmic stimuli had a density of 7 (contained 7 events).

Methods

Previous study (VanHandel 2024)

Current Study

6 7 8

Participant Information

Participants (n=456) were recruited through the UBC Human Subjects Pool and completed an online survey through Qualtrics.

Experimental Design

Participants answered a total of 194 questions, including:

    • 44 demographics questions and the Goldsmith Musical Sophistication Index (GMSI), measuring musical engagement;
    • 150 experimental task questions; participants were asked to listen to rhythmic patterns and rate the perceived complexity on a 6-point Likert scale:

Stimuli

The rhythmic patterns were selected to vary systematically in density, syncopation, and variability, and were created at six different tempos:

    • 333ms (180 bpm), 400ms (150 bpm), 533ms (113 bmp),

666ms (90 bpm), 800ms (75 bpm), and 933ms (64 bpm).

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Each participant was randomly assigned to one of two groups of four tempos:

    • Fast Tempo Group (n=238): 333ms, 400ms, 533ms, 666ms.
    • Slow Tempo Group (n=218): 533ms, 666ms, 800ms, 933ms.

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Discussion

Future Research

References

  • Successfully replicated VanHandel 2024 with new rhythmic patterns:
    • Density, syncopation, and variability are significant factors in perceived rhythmic complexity;
    • The strength of the effects of density, syncopation, and variability are tempo dependent
    • Reproduced the effect variability has on complexity ratings at density 7.
  • The strength of syncopation overtakes the density coefficient at 400ms rather than at 533ms compared to VanHandel 2024.

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  • Further investigation of the large data set collected in both this study and VanHandel 2024 will help clarify the factors relating to perceived rhythmic complexity.
  • This study confirmed the increase in strength of the effect of variability at density 7; future research will need to explore further to determine its cause.

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Brillon, C., & VanHandel, L. (2022). Perceived Complexity and Metrical Fit. [Unpublished thesis project]. School of Music, University of British Columbia, Vancouver, Canada.

Quinn, L, & VanHandel, L. (2021) Relation between rhythmic characteristics and perceptual complexity. [Unpublished thesis project]. School of Music, University of British Columbia, Vancouver, Canada.

VanHandel, L. (2024, November 7-10) Not just syncopation: rhythmic complexity is … complex [Conference presentation]. SMT 2024, Jacksonville, FL, United States.

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UBC VanLab