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 Hybrid room impulse response synthesis in digital waveguide mesh based room acoustics simulation The digital waveguide mesh (DWM) and related finite difference time domain techniques offer significant promise for room acoustics simulation problems. However high resolution 3-D DWMs of large spaces remain beyond the capabilities of current desktop based computers, due to prohibitively long run-times and large memory requirements. This paper examines how hybrid room impulse response synthesis might be used to better enable virtual environment simulation through the use of otherwise computationally expensive DWM models. This is facilitated through the introduction of the RenderAIR virtual environment simulation system and comparison with both real-world measurements and more established modelling techniques. Results demonstrate good performance against acoustic benchmarks and significant computational savings when a 2-D DWM is used as part of an appropriate hybridization strategy.
Download Spatial High Frequency Extrapolation Method for Room Acoustic Auralization Auralization of numerically modeled impulse responses can be informative when assessing the geometric characteristics of a room. Wave-based acoustic modeling methods are suitable for approximating low frequency wave propagation. Subsequent auralizations are perceived unnaturally due to the limited bandwidth involved. The paper presents a post-processing framework for extending low-mid frequency band limited spatial room impulse responses (SRIR) to include higher frequency signal components without the use of geometric modeling methods. Acoustic parameters for extrapolated RIRs are compared with reference measurement data for existing venues and a Finite Difference Time Domain modeled SRIR is extrapolated to produce a natural sounding full-band SRIR signal. The method shows promising agreement particularly for large venues as the air absorption is more dominant than the boundary absorption at high frequencies.