Brian Hamilton

Brian Hamilton

Ph.D.

About

50
Publications
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464
Citations

Publications

Publications (50)
Article
Full-text available
In room acoustics simulation and virtualization applications, accurate wall termination is a perceptually crucial feature. It is particularly important in the setting of wave-based modeling of 3D spaces, using methods such as the finite difference time domain method or finite volume time domain method. In this article, general locally reactive impe...
Thesis
Full-text available
Wave-based models of sound propagation can be used to predict and synthesize sounds as they would be heard naturally in room acoustic environments. The numerical simulation of such models with traditional time-stepping grid-based methods can be an expensive process, due to the sheer size of listening environments (e.g., auditoriums and concert hall...
Article
Full-text available
Air absorption can be a significant source of attenuation, which should be considered in long-duration wideband acoustics simulations. In this short contribution, a time-domain model for three-dimensional wave propagation including viscothermal and relaxation effects (air absorption) is developed and coupled with locally reactive impedance wall con...
Conference Paper
Full-text available
Air absorption effects lead to significant attenuation in high frequencies over long distances and this is critical to model in wide-band virtual acoustic simulations. Air absorption is commonly modelled using filter banks applied to an impulse response or to individual impulse events (rays or image sources) arriving at a receiver. Such filter bank...
Article
Full-text available
Most simulations involving metamaterials often require complex physics to be solvedthrough refined meshing grids. However, it can prove challenging to simulate the effect of localphysical conditions created by said metamaterials into much wider computing sceneries due to theincreased meshing load. We thus present in this work a framework for simula...
Article
Full-text available
Most simulations involving metamaterials often require complex physics to be solved through refined meshing grids. However, it can prove challenging to simulate the effect of local physical conditions created by said metamaterials into much wider computing sceneries due to the increased meshing load. We thus present in this work a framework for sim...
Preprint
Air absorption is an important effect to consider when simulating room acoustics as it leads to significant attenuation in high frequencies. In this study, an offline method for adding air absorption to simulated room impulse responses is devised. The proposed method is based on a modal scheme for a system of one-dimensional dissipative wave equati...
Preprint
This short contribution presents a method for generating $N$-point spherical configurations with low mesh ratios. The method extends Caspar-Klug icosahedral point-grids to non-icosahedral nets through the use of planar barycentric coordinates, which are subsequently interpreted as spherical area coordinates for spherical point sets. The proposed pr...
Article
No PDF available ABSTRACT Wave-based simulation models for acoustics have remained an active area of research and development for the past three decades. Wave-based methods aim to solve the 3D wave equation directly and therefore have large computational costs relative to conventional ray-based methods, which tend to simplify wave-diffraction effec...
Article
Full-text available
Sound absorbing micro-perforated panels (MPPs) are being increasingly used because of their high quality in terms of hygiene, sustainability and durability. The present work investigates the feasibility and the performance of MPPs when used as an acoustic treatment in lecture rooms. With this purpose, three different micro-perforated steel specimen...
Conference Paper
This paper investigates the use of two room acoustics metrics designed to evaluate the degree to which the linearity assumptions of the energy density curves are valid. The study focuses on measured and computer-modeled energy density curves derived from the room impulse response of a space exhibiting a highly non-diffuse sound field due to flutter...
Conference Paper
Full-text available
In room acoustics design, the use of acoustic diffusers for scattering sound reflections in an enclosed space is essential in terms of reducing artefacts and improving room acoustics quality. The scattering performance of a diffuser is largely determined by its surface geometry, and finding a geometrical pattern that produces maximum diffusion has...
Article
Full-text available
Computer modeling in acoustics allows for the prediction of acoustical defects and the evaluation of potential remediations. In this article, computer modeling is applied to the case of a barrel-vaulted sanctuary whose architectural design and construction led to severe flutter echoes along the main aisle, which was later mitigated through acoustic...
Article
Full-text available
Physical modeling synthesis has a long history. As computational costs for physical modeling synthesis are often much greater than in conventional synthesis methods, most techniques currently rely on simplifying assumptions: these include digital waveguides, as well as modal synthesis methods. While such methods are efficient, it can be difficult t...
Article
Full-text available
The modeling of source directivity is a problem of longstanding interest in virtual acoustics and auralisation. This remains the case for newer time domain volumetric wave-based approaches to simulation such as the finite difference time domain (FDTD) method. In this article, a spatio-temporal model of acoustic wave propagation, including a source...
Conference Paper
Full-text available
Time-domain wave-based simulation approaches such as the finite difference time domain (FDTD) method allow for a complete solution to the problem of virtual acoustics over the entire frequency range, in contrast with the methods of geometric acoustics which are valid in the limit of high frequencies. They also allow for flexible modelling of source...
Article
Volumetric time-domain simulation methods, such as the finite difference time domain (FDTD) method, allow for a fine-grained representation of the dynamics of the acoustic field. A key feature of such methods is complete access to the computed field, normally represented over a Cartesian grid. Simple solutions to the problem of extracting spatially...
Article
Volumetric wave-based acoustic simulation relies on the complete solution to the 3D wave equation over a spatial grid. Detailed modeling of sources, however, requires interpolation over the grid, which is complicated by the directional character of the source itself. In this article, a new model of point sources of arbitrary directivity and locatio...
Article
Full-text available
A major design consideration for volumetric wave-based time-domain room acoustics simulation methods, such as finite difference time domain (FDTD) methods, much be sufficiently general, or robust, to handle irregular room geometries and frequency-dependent and spatially varying wall conditions. A general framework for the design of such schemes is...
Article
Full-text available
The accurate simulation of wave propagation is a problem of long-standing interest. In this article, the focus is on higher-order accurate finite difference schemes for the wave equation in any number of spatial dimensions. In particular, two step schemes (which operate over three time levels) are studied. A novel approach to the construction of sc...
Chapter
The functioning of musical instruments is well described by systems of partial differential equations. Whether one's interest is in pure musical acoustics or physical modeling of sound synthesis, numerical simulation is a necessary tool, and may be carried out by a variety of means. One approach is to make use of so-called finite-difference or fini...
Conference Paper
Wave-based modeling in room acoustics and virtualisation applications constitutes an alternative to geometric or ray-based approaches ; finite difference time domain (FDTD) methods, defined over regular grids, are an excellent match to parallel architectures. Acoustic sources are typically included as monopoles or collections of monopoles, realised...
Conference Paper
Full-text available
In this paper we present a hybrid brass instrument model consisting of two parts: a 1D wave propagation model for the slowly varying bore profile that includes viscous and thermal losses; and a 3D wave propagation model under rigid boundary termination for the bell section, allowing for lossless radiation into an open 3D space. These 1D and 3D mode...
Article
Time domain wave-based methods sidestep the consequences of the simplifying hypotheses that are part of geometric ray-based methods when simulating, modeling, and analyzing room acoustics. This paper illustrates construction techniques for wave-based simulation methods when applied to nontrivial problems in room acoustics, including irregular geome...
Conference Paper
Full-text available
Room acoustics modelling requires numerical methods that can simulate the wave behaviour of sound across a wide band of frequencies while taking into account the frequency-dependent characteristics of absorption in air and at walls, but the accurate and stable numerical modelling of complex room geometries under frequency-dependent boundary conditi...
Conference Paper
Full-text available
Wave-based methods are increasingly viewed as necessary alternatives to geometric methods for room acoustics simulations, as they naturally capture wave phenomena like diffraction and interference. For methods that simulate the three-dimensional wave equation—and thus solve for the entire acoustic field in an enclosed space—computational costs can...
Conference Paper
Full-text available
The design of stable time domain numerical simulation methods for room acoustics simulation is a challenging problem. One chief difficulty is in the determination of appropriate stable boundary terminations, particularly when the room geometry is irregular, and when the wall condition is spatially-varying and/or frequency-dependent in a non-trivial...
Article
Full-text available
Finite-difference time-domain (FDTD) simulation has been a popular area of research in room acoustics due to its capability to simulate wave phenomena in a wide bandwidth directly in the time-domain. A downside of the method is that it introduces a direction and frequency dependent error to the simulated sound field due to the non-linear dispersion...
Conference Paper
Full-text available
Wave-based simulation methods for room acoustics applications, whether for purposes of auralisation, or artificial reverberation, offer an increasingly viable alternative to computationally cheaper geometrical acoustics based methods. The advantage is that one has, at least in principle, a means of simulating the entire acoustic field in an enclosu...
Conference Paper
Full-text available
Stencil operations are often a key component when performing acoustics simulations, for which the specific choice of implementation can have a significant effect on both accuracy and computational performance. This paper presents a detailed investigation of computational performance for GPU-based stencil operations in two-step finite difference sch...
Conference Paper
Full-text available
Viscothermal effects in air lead to a damping of high frequencies over time. Such effects cannot be neglected in large-scale room acoustics simulations for the full audible bandwidth. In this study, full-bandwidth room acoustics is modelled using a variant of the three-dimensional wave equation including viscothermal losses in air following from a...
Conference Paper
Full-text available
The thin plate is a key structure in various musical instruments, including many percussion instruments and the soundboard of the piano, and also is the mechanism underlying electromechanical plate reverberation. As such, it is a suitable candidate for physical modelling approaches to audio effects and sound synthesis, such as finite difference met...
Conference Paper
Full-text available
Time-domain finite difference (FD) and digital waveguide mesh (DWM) methods have seen extensive exploration as techniques for physical modelling sound synthesis and artificial reverberation. Various formulations of these methods have been unified under the FD framework, but many discrete boundary models important in room acoustics applications have...
Conference Paper
Full-text available
Implicit finite difference schemes for the 3-D wave equation using a 27-point stencil on the cubic grid are presented, for use in room acoustics modelling and artificial reverberation. The system of equations that arises from the implicit formulation is solved us-ing the Jacobi iterative method. Numerical dispersion is analysed and computational ef...
Conference Paper
Full-text available
In this paper, a physics-based model for a snare drum will be dis-cussed, along with its finite difference simulation. The interactions between a mallet and the membrane and between the snares and the membrane will be described as perfectly elastic collisions. A novel numerical scheme for the implementation of collisions will be presented, which al...
Article
Full-text available
It is shown that half of the points on the diamond grid are redundant for sampling and reconstructing a bandlimited 3-D signal. This redundancy is then exploited to show that the tetrahedral digital waveguide mesh requires four times more computational density and twice the memory storage for the same approximation as a finite difference scheme on...
Conference Paper
Full-text available
This paper investigates some fourth-order accurate explicit finite difference schemes for the 2-D wave equation obtained using 13-, 17-, 21-, and 25-point discrete Laplacians. Optimisation is con- ducted in order to minimise numerical dispersion and computa- tional costs. New schemes are presented that are more computa- tionally efficient than nine...
Article
Full-text available
With the advent of high performance parallel computing, audio rate room auralization using finite difference time domain (FDTD) methods is becoming possible in a reasonable computation time. Yet, there are still deficiencies in the methods, which are used for this purpose, particularly with regard to minimizing numerical dispersion over the full ra...
Conference Paper
Full-text available
Finite difference schemes for the 2-D wave equation operating on hexagonal grids and the accompanying numerical dispersion properties have received little attention in comparison to schemes operating on rectilinear grids. This paper considers the hexagonal tiling of the wavenumber plane in order to show that the hexagonal grid is a more natural cho...
Conference Paper
Full-text available
A room acoustics simulation using a finite difference approxima- tion on a face-centered cubic (FCC) grid with finite volume impedance boundary conditions is presented. The finite difference scheme is accelerated on an Nvidia Tesla K20 graphics processing unit (GPU) using the CUDA programming language. A performance comparison is made between 27-po...
Conference Paper
Full-text available
Sound synthesis based on physical models of musical instruments is, ultimately, an exercise in numerical simulation. As such, for complex systems of the type seen in musical acoustics, simulation can be a computationally costly undertaking, particularly if simplifying hypotheses, such as those of traveling wave or mode decompositions are not employ...
Conference Paper
Full-text available
In this paper, we investigate finite difference schemes for the 3-D wave equation using 27-point stencils on the cubic lattice, a 13-point stencil on the face-centered cubic (FCC) lattice, and a 9-point stencil on the body-centered cubic (BCC) lattice. The tiling of the wavenumber space for non- Cartesian grids is considered in order to analyse num...
Conference Paper
Full-text available
In this paper, we present a unified view of three non-stationary sinusoidal parameter estimation methods which are based on taking linear transforms of a signal and its derivatives. These methods, the Distribution Derivative Method (DDM), the Generalized Derivative Method (GDM), and the Generalized Reassignment Method (GRM), are shown to be subcase...
Conference Paper
Full-text available
In this paper, we present comparisons of non-stationary sinusoidal parameter estimation methods for an exponential polynomial signal model. We compare the estimations of the Distribution Derivative Method (DDM), the Generalized Derivative Method (GDM), the Generalized Reassignment Method (GRM), and the Quadratically Interpolated Fast Fourier Transf...
Conference Paper
Full-text available
In the context of non-stationary sinusoidal analysis, the theoretical comparison of the reassignment method (RM) and the derivative method (DM) for the estimation of the frequency slope is investigated. It is shown that for the estimation of the frequency slope the DM differs from the RM in that it does not consider the group delay. Theoretical equ...

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Projects

Projects (2)
Project
Large-scale time-domain simulation for room acoustics problems
Project
The NESS Project is a five-year European Research Council funded project (ERC-StG-2011-279068-NESS) concerned with large scale sound synthesis based on physical models of acoustic systems. The systems include many commonly encountered instrument types, such as the brass family, string instruments such as violins and guitars, percussion instruments including drums and gongs, as well as full rendering in 3D acoustic spaces. As such synthesis techniques can be computationally demanding, we make use of parallel hardware, including graphics processing units (GPUs) in order to accelerate calculation. Finally, we work directly with composers to create pieces of fully synthetic multichannel music. The NESS Project is a collaborative effort between the Acoustics and Audio group and the Edinburgh Parallel Computing Centre at the University of Edinburgh.