A system for controlling the directivity of sound radiated from a structure

Abstract

Directional sound fields can be generated by arrays of multiple sound sources such as loudspeaker drivers. These systems, though potentially capable of high levels of directivity control over a broad bandwidth, may prove prohibitively expensive, fragile, or impracticable in certain applications. To overcome these limitations, this paper presents an investigation into the design and limitations of a directional structural-actuator-based array. This provides an affordable and robust alternative to conventional loudspeakers, particularly when the actuators can be used to radiate via a pre-existing structure and where the required audio quality is lower, or the bandwidth somewhat limited. In the first instance, an analytical model is formulated, and used to perform a simulation-based parametric study, which provides insights into the design trade-offs. Based on this study, a physical prototype is constructed using six actuators and a flat panel, which enables the model to be experimentally validated and an evaluation of the directional radiation capabilities of the proposed system to be carried out. Experiments show that the simple analytical model is an effective tool in designing such arrays, predicting the trends in the behaviour of the prototype, and that the structural actuator-based system is capable of controlling directivity within its intended operational bandwidth.

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Identifiers

ORCID for Jordan Cheer: orcid.org/0000-0002-0552-5506

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