Download 2-D digital waveguide mesh topologies in room acoustics modelling
Digital waveguide mesh models have provided an accurate and efficient method of modelling the properties of many resonant structures, including acoustic spaces. 2-D rectilinear and triangular mesh structures have been used extensively in the past to model plates and membranes and are presented here as potential analogues to 2-D acoustic spaces. Impulse response measurements are taken and comparisons are made regarding the spectral content and the associated properties when compared with standard room acoustic parameters. Enhanced mesh structures are examined using frequency warping techniques and high-resolution sampling rates. The 2-D triangular mesh is shown to be considerably superior to the rectilinear mesh in terms of the measurements taken, with a further significant improvement being made by using the same mesh oversampled to a much higher resolution to improve the bandwidth of the measured impulse responses.
Download Digital Waveguide Mesh Modelling Of Room Acoustics: Surround-Sound, Boundaries And Plugin Implementation
Digital waveguide mesh models have provided an accurate and efficient method of modelling the properties of many resonant structures, including acoustic spaces. 2-D rectilinear and triangular mesh structures have been used extensively in the past to model plates and membranes and as potential analogues to 2-D acoustic spaces. This paper looks at current developments relating to this technique and attempts to highlight potential ways forward for this research. This includes an investigation into the potential suitability of this technique for surround-sound applications and a realtime implementation as a VST plugin.
Download Real-Time Partial Tracking in an Augmented Additive Synthesis System
This paper describes an approach to real time partial tracking in an analysis\transformation\resynthesis system using a combination of linear and bi-linear time-frequency techniques. Tests of the system have been made using both natural and synthetic sounds. Results are presented and areas for further research and development are discussed.
Download Digital Waveguide Mesh Modeling of Room Acoustics: Improved Anechoic Boundaries
Digital waveguide mesh structures have proved useful in a wide variety of modelling applications. When modelling the acoustics of an enclosed space the accurate simulation of specific boundary conditions is paramount but waveguide mesh related techniques have as yet to provide an appropriate and reliable solution. This paper gives an overview of boundary types that have been implemented by researchers to date and describes the application of a higher order approximation for the particular case of an anechoic boundary, that may prove useful as part of a more general solution.
Download Real time spectral expansion for creative and remedial sound transformation
In this paper we describe the implementation, use and applications of WaveThresh, a real time Fourier\wavelet spectral expander. Expansion and reverse-expansion of spectral components is offered. In order that analysis methods can be better adapted to the signal we offer a combined wavelet\Fourier mode. This mode separates sinusoids from the rest of the signal (residual) and applies Fourier analysis to the sinusoids and wavelet analysis to the residual.
Download Archaeological Acoustic Space Measurement for Convolution Reverberation and Auralization Applications
Developments in measuring the acoustic characteristics of concert halls and opera houses are leading to standardized methods of impulse response capture for a wide variety of auralization applications. This work presents results from a recent UK survey of non-traditional performance venues focused in the field of acoustic archaeology. Sites are selected and analyzed based on some feature of interest in terms of their acoustic properties. As well as providing some insight as to the characteristics and construction of these spaces, the resulting database of measurements has a primary use in convolution based reverberation and auralization. A recent sound installation based on one of the selected sites is also presented.
Download High Accuracy Frame-by-Frame Non-Stationary Sinusoidal Modelling
This paper describes techniques for obtaining high accuracy estimates, including those of non-stationarity, of parameters for sinusoidal modelling using a single frame of analysis data. In this case the data used is generated from the time and frequency reassigned short-time Fourier transform (STFT). Such a system offers the potential for quasi real-time (frame-by-frame) spectral modelling of audio signals.
Download 2nd Order Spherical Harmonic Spatial Encoding of Digital Waveguide Mesh Room Acoustic Models
The aim of this research is to provide a solution for listening to the acoustics of Digital Waveguide Mesh (DWM) modelled virtual acoustic spaces. The DWM is a numerical simulation technique that has shown to be appropriate for modelling the propogation of sound through air. Recent work has explored methods for spatially capturing a soundfield within a virtual acoustic space using spatially distributed receivers based on sound intensity probe theory. This technique is now extended to facilitate spatial encoding using second-order spherical harmonics. This is achieved through an array of pressure sensitive receivers arranged around a central reference point, with appropriate processing applied to obtain the second-order harmonic signals associated with Ambisonic encoding/decoding. The processed signals are tested using novel techniques in order to objectively assess their integrity for reproducing a faithful impression of the virtual soundfield over a multi-channel sound system.
Download Short-Time Wavelet Analysis of Analytic Residuals for Real-Time Spectral Modelling
This paper describes an approach to using compactly supported spline wavelets to model the residual signal in a real-time (frameby-frame) spectral modelling system. The outputs of the model are time-varying parameters (gain, centre frequency and bandwidth) for filters which can be used in a subtractive resynthesis system.