A Framework for Dynamic Expressivity in Improvised Acoustic Guitar Music

Thesis Abstract

This study addresses the challenge of articulating and systematizing dynamic expressivity within improvised acoustic guitar performance, where real-time decisions about tempo, timbre, articulation, and micro-phrasing shape listener perception yet lack a cohesive evaluative framework. The aim is to develop a robust framework for dynamic expressivity that integrates perceptual, cognitive, and performative dimensions to model how improvisers modulate expressive parameters across real-time musical discourse. Specific objectives are (1) to identify core expressive parameters employed in improvised acoustic guitar passages through expert musician interviews and performance transcriptions; (2) to construct a theoretical model linking expressive intention, gestural execution, and perceptual outcomes using constructivist and embodied cognition perspectives; (3) to operationalize the framework into measurable constructs and predictive indicators for dynamic expressivity; (4) to validate the model through empirical data from controlled improvisation sessions and audience perception studies; and (5) to propose guidelines for pedagogy and performance practice that enhance communicative clarity in improvised contexts. The methodology adopts a mixed-methods design, beginning with qualitative interviews with 18 professional jazz and contemporary acoustic guitarists to elicit expressive strategies, followed by a corpus study of 60 improvised performances captured with high-fidelity audio and motion capture of the dominant hand and wrist to quantify gestural dynamics. Data collection instruments include a semi-structured interview protocol, transcriptions using conventional notational practices, instrumented performance recordings at 48 kHz/24-bit, and perceptual rating scales administered to 120 listeners in a double-blind design. Quantitative analysis comprises time-series analysis of expressive parameters (loudness, spectral centroid, attack/decay rates, vibrato rate and depth) and gestural metrics (velocity, acceleration, contact force) derived from motion capture data, followed by multivariate regression and structural equation modeling to test the proposed relations between performer intention, gesture, and listener-rated expressivity. The qualitative component employs thematic analysis to identify emergent themes of expressivity strategies and corroborates them with quantitative findings through triangulation. The theoretical basis integrates embodied cognition and action–perception theories with existing models of musical expressivity, notably the Dynamic Systems Theory approach to gesture–sound coupling and the Perceptual Evaluation of Expressive Performance framework. Expected findings include (a) a set of core dynamic expressivity parameters with fixed and contingent weighting across genres, (b) empirical evidence linking specific gestural profiles to perceived expressivity levels, and (c) a validated operational model that maps performer intents to measurable acoustic and gestural outcomes. The study aims to contribute to knowledge by offering a concrete, transferable framework that explains how improvisers negotiate real-time expressive decisions and how audiences interpret those decisions, thereby filling gaps in the literature on improvisational expressivity in non-lexical instrumental contexts. Anticipated theoretical contributions include an integrated model that reconciles motor control, perceptual processing, and musical meaning in improvised guitar performance, alongside a methodological blueprint for combining motion capture with perceptual testing in music research. Practical implications encompass pedagogical resources for guitar education, performance practice guidelines to enhance communicative clarity in live improvisation, and considerations for instrument design that accommodate dynamic expressive gesturing. The study concludes that dynamic expressivity in improvised acoustic guitar emerges from the tight coupling of gestural timing, timbral modulation, and perceptual salience, moderated by performer intent and contextual expectations. Recommendations address curriculum development for improvisation training, development of real-time feedback tools for learners, and avenues for future research exploring cross-cultural and genre-specific expressivity patterns, including extended techniques and amplified acoustic guitar settings.