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The University of Southampton

Analysis and Control of Acoustic Modes in Cylindrical Cavities with application to Direct Field Acoustic Noise (DFAN) Testing Seminar

16:00 - 17:00
30 November 2022
Building 13, room 3017

For more information regarding this seminar, please telephone Vanui Mardanyan on or email .

Event details

ISVR Research seminar.

It is well known that acoustic cavities have frequencies at which certain free-response ‘modes’ of propagation respond especially strongly. In the absence of significant damping, these cause peaks of high SPL in the frequency response as well as spatial non-uniformity and temporal ringing.

The spatial non-uniformity is especially problematic since it means the room cannot be ‘EQ’d’ to compensate, since the SPL is different in different positions. This phenomenon has been studied extensively in the room acoustics literature and various strategies for mitigation proposed. Many of these make use of the theoretical mode shapes for a cuboid with a rigid boundary condition, since this is a common shape of room and a reasonable approximation for a solidly constructed wall. But modes exist for other shape spaces too.

Of particular interest is the cylindrical cavity that is formed when large enclosing arrays of loudspeakers are used to perform high-intensity acoustic tests on space hardware such as satellites. These possess problematic modes that can cause over-testing in some positions and under-testing in others.

In this work, it is investigated how a simple FEM simulation can compute Q-factors for these modes and identify which will be problematic. How this might inform control system design is discussed.

Speaker information

Dr Jonathan Hargreaves , University of Salford. 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 IOA Research Coordination Committee and the UK Acoustics Network Special Interest Group for Computational Acoustics. 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.

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