Wed 17th Dec 2025 12:00 – 13:00 UK time. Hybrid: Newton 234-237 on campus or Microsoft Teams.
Dr Jonathan Hargreaves will present a slightly extended version of the talk he gave at the IOA Reproduced Sound conference in November of 2025.
Abstract:
In recent years, measurement methods have emerged that can measure loudspeaker directivity holographically. In these, measurements are taken in the nearfield of the loudspeaker, then the acoustic field they sample is propagated out to the desired evaluation distance mathematically. These methods are notable because they can separate incoming and outgoing components in the sound field, allowing the former to be eliminated and meaning free-field measurements can be performed in non-anechoic environments. They are, however, also limited because they must measure on a surface fully enclosing the loudspeaker, which can be costly or impractical. This paper proposes an alternative approach, where measurements are taken solely on the radiating face of the loudspeaker, the data from which is then inserted into a Boundary Element Method model with other surfaces of the cabinet assumed rigid. It will present the core theory, discuss limitations and measurement hardware, and present some early results.
Authors:
Dr Jonathan Hargreaves & Toby Charity, Acoustics Research Centre, University of Salford.
Biography:
Jonathan was awarded an MEng in Engineering & Computing Science from the University of Oxford in 2000 and a PhD in Acoustic Engineering from the University of Salford in 2007, where he remains as a Lecturer in Acoustic and Audio Engineering. He is best known for his research on novel computational acoustic algorithms, but he also has strong research interests in loudspeaker design and characterisation, material characterisation, and microphone arrays. He is a member of the UK Acoustics Network Special Interest Group for Computational Acoustics and an Associate Editor for Computational Acoustics for JASA Express Letters. Jonathan has had the pleasure of being involved in a wide variety of public engagement activities, including a number of TV appearances, and is passionate about performing, engineering and enjoying live music. He was awarded the UK Institute of Acoustics’ Tyndall Medal, for outstanding contribution to acoustics research and education, in September 2016.
Toby Charity completed a BSc Physics with Acoustics from 2020 to 2023, followed by an MSc in Acoustics from 2023 to 2024, both at the University of Salford. He began his PhD studies in February 2025 in vibroacoustics at the University of Salford’s Acoustic Research Centre, focusing on enhancement of the dynamical energy analysis (DEA) framework. His undergraduate dissertation introduced a new method to determine low frequency sound transmission, which he developed into a conference paper during his MSc studies. This work was presented at the 2024 Institute of Acoustics (IoA) Conference. For his masters dissertation, Toby explored his passion for loudspeaker design, conducting an experiment for loudspeaker characterisation through near-field scans. He also currently works to support Salford University’s Acoustic Laboratories in Laser Doppler Vibrometry measurements alongside his PhD. Outside of academia, Toby is deeply engaged in music, from music production to music journalism.