Acoustics

Computer Modelling of Sound

The ability to model a sound field accurate is fundamental to the understanding of the underlying characteristics of the sound and how the sound can be manipulated and controlled. The advance of computational technology, both in hardware and software, has enabled us to make great progresses in modelling ever more sophisticated sound fields in realistic indoor and outdoor environments.    

The impact of works in this area can be seen in the design of acoustic performance spaces such as studios, concert halls and soundscapes in urban design; the development of novel and high performance acoustic materials such as sonic cloaks and active absorbers; and more effective control of noise such as novel noise barriers, metal cladding with high noise insulation, and active noise shielding technology.    

At Salford we continue to be at the forefront of developing new techniques for modelling and sound, and the use of such modelling techniques to tackle pertinent practical acoustical and related problems. We have developed and used a wide range of numerical techniques for computer modelling, including (among others) geometrical methods, boundary element methods, finite element methods, finite difference methods, parabolic equation methods, and combinations thereof.    

As examples, we recently had a research project funded by the UK Engineering and Physical Science Research Council (EPSRC) to develop a hybrid boundary element method to take advantage of the efficiency of asymptotic geometrical approximation in a full-wave boundary element formulation. Other projects have used computer modelling techniques to underpin the study of future spatial audio rendering in homes and other challenging environments, such as in an EPSRC funded Programme Grant with partners from the BBC, University of Surrey and University of Southampton.    

The followings are examples of our current and previous works in this area and selected publications.

Boundary Element Modelling

Scene 3 from the Benchmark for Room Acoustical Simulation database, as simulated in Hargreaves et al 2019.

Measured versus simulated Binaural Room Impulse Responses (low pass filtered at 1kHz)

Geometrical Room Acoustics Modelling    

  • Emthyas, A, and Hargreaves, JA, Raytracing in galerkin boundary integral form, in: Proc. Internoise 2022
  • Lam Y. W., “Issues for Computer Modelling of Room Acoustics in Non-Concert Hall Settings”, Acoust. Sci. & Tech. 26(2), pp.145-155, 2005. 
  • Drumm I. A. and Lam Y. W., “The adaptive beam tracing algorithm”, J. Acous. Soc. Am. 107(3), pp.1405-1412, 2000.      
  • Lam Y.W., “The dependence of diffusion parameters in a room acoustics prediction model on auditorium sizes and shapes”, J. Acous. Soc. Am. 100(4), p.2193-2203, 1996      
  • Lam Y.W., “A comparison of three diffuse reflection modelling methods used in room acoustics computer models”, J. Acous. Soc. Am. 100(4), p.2181-2192, 1996           

Synergies between Wave and Geometrical Simulation

Time Domain Boundary Element Modelling

  • Hargreaves, J. (2011). Simulating transient scattering from obstacles with frequency-dependent surface impedance. In Forum Acusticum (pp. 229–234). Aalborg. http://usir.salford.ac.uk/19382/
  • Hargreaves, J., & Cox, T. (2009). A transient boundary element method for acoustic scattering from mixed regular and thin rigid bodies. Acta Acustica United With Acustica, 95(4), 678–689. Retrieved from http://usir.salford.ac.uk/14082/
  • Hargreaves, J. A, & Cox, T. J. (2008). A transient boundary element method model of Schroeder diffuser scattering using well mouth impedance. The Journal of the Acoustical Society of America, 124(5), 2942–51. http://usir.salford.ac.uk/14625/

Finite Element Modelling    

Finite Difference Time Domain Modelling    

  • Sheaffer, J & Walstijn, M V & Fazenda, B 2014, ‘Physical and numerical constraints in source modeling for finite difference simulation of room acoustics’, Journal of the Acoustical Society of America, 135(1), pp.251-261.
  • J. Sheaffer, C.J. Webb and B.M. Fazenda. Modelling binaural receivers in finite difference simulation of room acoustics. In: Proceedings of the 21st International Congress on Acoustics (ICA 2013), June 6–12, 2013.
  • Jeong H. and Lam Y. W., “Source implementation to eliminate low-frequency artifacts in finite difference time domain room acoustic simulation”, J. Acoust. Soc. Am. 131(1): 258–268 (2012).
  • Lam Y. W., Jeong H., “Source and boundary modeling in FDTD for room acoustics”, Internoise 2011, Osaka, Sept 2011.
  • Jeong H. and Lam Y. W., “FDTD modelling of frequency dependent boundary conditions for room acoustics”, Proc. 20th International Congress on Acoustics, Paper 488, Sydney, Aug. 2010.
  • Drumm I., Lam Y. W., “Development and assessment of a finite difference time domain room acoustic prediction model that uses hall data in popular formats”, Proc. Internoise 2007, Paper IN07_022, Istanbul, August 2007.

Click the image to play ‘Echo Bridge Reflections’ – a simulation of how the sound bounces around under Echo Bridge in Newton Upper Falls, Massachusetts. Simulation done by Jonathan Sheaffer, a PhD student at the University of Salford.

Modelling for Outdoor Sound Propagation    

  • Hargreaves, J. A, Kendrick, P. K. & Von-Hunerbein, S. Simulating acoustic scattering from atmospheric temperature fluctuations using a k-space method, J. Acoust. Soc. Am., 124(5) pp. 82-92, 2014.
  • Lam Y. W. “An analytical model for turbulence scattered rays in the shadow zone for outdoor sound propagation calculation”, J. Acoust. Soc. Am., 125(3), pp.1340-1350, 2009.      
  • Lam Y. W., “The significance of temperature gradient on the propagation of noise to high rise buildings in urban cities”, Paper in08_0337, Proc. Internoise 2008, 26-29 October 2008, Shanghai, China.      
  • Lam Y. W., Monazzam M. R., “On the modelling of sound propagation over multi-impedance discontinuities using semi-empirical diffraction formulations”, J. Acoust. Soc. Am. 120(2), pp.686-698, 2006.      
  • Munt R M, Browne R W, Simpson C, Bradley S, Lam Y W, Kerry G, Beaman R, “Environmental Noise Modelling for UK Military Helicopter Training Operations”, Proc. Of American Helicopter Society 59th Forum, 2003.      
  • Lam Y. W., “Ground and Meteorological Effects on Sound Propagation in the Atmosphere – Predictions and Measurements”, International Journal of Acoustics and Vibration Vol. 5(3), pp.135-139, 2000.    

Modelling for Acoustical Materials    

Modelling of Active Noise Control & Direct Field Acoustic Testing    

  • Hargreaves, JA, Analysis and control of acoustic modes in cylindrical cavities with application to Direct Field Acoustic Noise (DFAN) testing , in: Proc. Internoise 2022
  • Lam Y. W., Utyuzhnikov S. V., Kelly L., “Difference potential based active noise shielding in three dimensional settings”, J. Acoust. Soc. Am. 131, 3380 (2012).
  • Lim H., Utyuzhnikov S. V., Lam Y. W., and Turan A., “Multi-domain active sound control and noise shielding”, J.Acous.Soc.Am. 129(2), 717-725 (2011).
  • Lim H., Lam Y. W., Utyuzhnikov S. V., Turan A., “Realization of the Difference Potential Method in Active Noise Control”, WESPAC 2006, 26-18 June, 2006, Seoul, South Korea.