Outputs (52)

Understanding human responses to air source heat pump noise: examining tonal changes and operating cycles (2024)
Presentation / Conference Contribution

Air Source Heat Pumps are pivotal in the Government of the United Kingdom's target of achieving net zero carbon emissions by 2050. However, their widespread adoption faces challenges, with noise being among the main barriers to entry and a restrictin... Read More about Understanding human responses to air source heat pump noise: examining tonal changes and operating cycles.

Higher-fidelity analysis of air source heat pump noise via scanning intensity measurement (2024)
Presentation / Conference Contribution

The need to shift to reduce carbon emissions to hit Net Zero is currently driving plans for large scale rollouts of Air Source Heat Pumps (ASHPs), due to their increased thermal efficiency and lack of direct carbon emissions. Concern exists, however,... Read More about Higher-fidelity analysis of air source heat pump noise via scanning intensity measurement.

Confidence limits for coherence – toward a better understanding of its use as a diffuse field metric for quantifying the quality of Direct Field Acoustic Noise (DFAN) Testing systems (2024)
Presentation / Conference Contribution

To determine the degree of diffuseness of a particular acoustic field, an oft-considered metric is the coherence between spaced pairs of measurement microphones. This is useful because the expected theoretical ‘sinc2’ trend for a diffuse field is wel... Read More about Confidence limits for coherence – toward a better understanding of its use as a diffuse field metric for quantifying the quality of Direct Field Acoustic Noise (DFAN) Testing systems.

Extending the Low Frequency Acoustic Centre Concept to Directional Loudspeakers (2023)
Presentation / Conference Contribution

The Acoustic Centre of a loudspeaker is defined as being the point from which spherical waves appear to radiate. This is useful to know when performing phase, level, or time alignment, for example. For a single driver in a sealed box, it is typically... Read More about Extending the Low Frequency Acoustic Centre Concept to Directional Loudspeakers.

Adventures in High Intensity Acoustic Testing: a Loudspeaker System for Small-Scale Tests (2023)
Presentation / Conference Contribution

In the space and aerospace industry, there is a need to perform High Intensity Acoustic Testing (HIAT). This aims to recreate in the laboratory, for the purpose of qualification testing, the extreme acoustic environments that designs must survive in... Read More about Adventures in High Intensity Acoustic Testing: a Loudspeaker System for Small-Scale Tests.

Iterative metric-based waveguide optimisation (2023)
Presentation / Conference
MacDonald, L., Oclee-Brown, J., Dodd, M., & Hargreaves, J. (2023, October). Iterative metric-based waveguide optimisation. Paper presented at 155th Audio Engineering Society Convention, New York

A comparison between the high-frequency Boundary Element Method and Surface-Based Geometrical Acoustics (2023)
Journal Article
Hargreaves, J. (2023). A comparison between the high-frequency Boundary Element Method and Surface-Based Geometrical Acoustics. https://doi.org/10.3397/in_2022_1005

The audible frequency range covers many octaves in which the wavelength changes from being large with respect to dominant features of a space to being comparatively much smaller. This makes numerical prediction of a space's acoustic response, e.g. fo... Read More about A comparison between the high-frequency Boundary Element Method and Surface-Based Geometrical Acoustics.

A 'Surface-based' Geometrical Acoustic formulation within a Galerkin Boundary Element framework (2022)
Thesis
Emthyas, A. A 'Surface-based' Geometrical Acoustic formulation within a Galerkin Boundary Element framework. (Dissertation). University of Salford

As sound propagates within a room, it experiences high-order reflection, diffraction, and scattering. This causes the reflection density to increase over time, such that the sound field becomes diffuse and chaotic. Under these conditions, there is li... Read More about A 'Surface-based' Geometrical Acoustic formulation within a Galerkin Boundary Element framework.

Metric-based optimisation of acoustic lenses and waveguides (2022)
Thesis

This dissertation develops an automated procedure for the design of acoustic waveguides that can support single parameter (1P) wave propagation over a large bandwidth. 1P waves include plane, cylindrical and spherical waves, and the waveguides aim to... Read More about Metric-based optimisation of acoustic lenses and waveguides.

Analysis and control of acoustic modes in cylindrical cavities with application to Direct Field Acoustic Noise (DFAN) testing (2022)
Presentation / Conference
Hargreaves, J. (2022, August). Analysis and control of acoustic modes in cylindrical cavities with application to Direct Field Acoustic Noise (DFAN) testing. Presented at Internoise 2022, Glasgow, Scotland

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 spat... Read More about Analysis and control of acoustic modes in cylindrical cavities with application to Direct Field Acoustic Noise (DFAN) testing.