On 8 October 2026, at 10:30 a.m., Miguel Carvalho, MSc, will defend his PhD thesis in Musical Sciences, entitled “Preservation of historical bells: characterization and physical modeling techniques for tuning and sound synthesis”, under the supervision of Vincent Debut, José Vieira Antunes and João Soeiro.
The defence will take place in Auditorium A223, on the 2nd floor of Colégio Almada Negreiros, at the Campolide Campus of NOVA School of Social Sciences and Humanities (NOVA FCSH).
PhD Defence Jury
- Prof. Dr. Luísa Mariana de Oliveira Rodrigues Cymbron (ULisboa)
- Prof. Dr. João Soeiro de Carvalho (Ulisboa)
- Prof. Dr. Octávio José Patrício Fernandes Inácio (InAcoustics)
- Prof. Dr. Luís Carlos Pereira Sebastian (FLUP)
- Prof. Dr. Luc Rombouts (KU Leuven)
- Dr. Joost Eijsbouts, (Royal Eijsbouts)
Preservation of historical bells: characterization and physical modeling techniques for tuning and sound synthesis
scientific and technical challenges due to their complex vibrational behaviour and the irreversible nature of traditional tuning practices. This thesis addresses these challenges through an interdisciplinary approach combining innovative methodologies from historical musicology and musical acoustics, with the aim of developing scientific techniques for the analysis, characterization and non-destructive tuning of historical bells, with particular emphasis on the carillons of the National Palace of Mafra.
This research is presented as a set of interconnected studies that progressively deepen the understanding of bell acoustics, vibrational behaviour and tuning techniques. First, a comprehensive historical and technical review of bell design and tuning practices is presented, discussing the evolution of bell founding and identifying the main factors influencing tuning accuracy, namely material properties, casting techniques, bell geometry and tuning strategies. This review highlights the empirical origins of these practices and the gradual integration of scientific methods leading to contemporary approaches.
Building on this framework, experimental and theoretical techniques for vibrational analysis are developed in order to assess the tuning condition of the Mafra carillons. A specific modal identification methodology adapted to historical bells is presented, enabling the identification of modal frequencies, decay times and “warble”, while also allowing for the partial reconstruction of their original pitch standards and target temperaments.
A comprehensive methodological framework is then proposed for the dynamic characterization and sound synthesis of bells, combining high-resolution 3D imaging techniques, finite element modelling, experimental modal analysis and physics-based sound synthesis techniques. This approach enables the accurate digital reconstruction of historical bells, providing a robust tool for acoustic analysis, virtual preservation and the documentation of cultural heritage.
Finally, one of the central contributions of this thesis lies in the development of an innovative non-destructive tuning technique based on optimized structural modifications. Initially validated on bar percussion instruments, the method is subsequently extended to bells, enabling multimodal tuning through the strategic attachment of point masses without removing material. By combining modal formulations with optimization algorithms, this approach provides a reversible and computationally efficient solution for correcting the tuning of historical bells.
The methodologies developed in this thesis have been published in international peer-reviewed scientific journals in the field of musical acoustics and have also been successfully validated and transferred to the industrial sector. Taken as a whole, this work represents a significant advance in the field of campanology, providing new tools for the preservation and tuning of historical bells.
Keywords
Musical acoustics; Historical bells; Carillons; Non-destructive tuning; Modal analysis; Structural dynamics; Finite element modelling; Sound synthesis; Cultural heritage.