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S. Sørsdal

Bio: S. Sørsdal is an academic researcher from Norwegian Institute of Technology. The author has contributed to research in topics: Ray tracing (graphics) & Beam tracing. The author has an hindex of 3, co-authored 3 publications receiving 495 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the distribution of early reflected sound over the audience areas in concert halls is investigated, especially with respect to the shape of halls, based on geometrical acoustics, using a ray tracing technique.

476 citations

Journal ArticleDOI
TL;DR: A computer program is described which displays the space, time and directional distribution of energy in a room and has been used in room acoustical planning and in the design of sound reinforcement systems.

36 citations

Journal ArticleDOI
TL;DR: Bjergsted concert hall in Stavanger, Norway, was opened in 1982 as a multi-purpose hall, but primarily intended for concerts as mentioned in this paper. The hall has been rebuilt from an old dome-shaped exhibition hall.

4 citations


Cited by
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Journal ArticleDOI
TL;DR: The technique presented in this work enables designers to undertake a preliminary analysis of a simulated reverberant environment without the need for time-consuming image-method simulations.
Abstract: A method is proposed that provides an approximation of the acoustic energy decay (energy–time curve) in room impulse responses generated using the image-source technique. A geometrical analysis of the image-source principle leads to a closed-form expression describing the energy decay curve, with the resulting formula being valid for a uniform as well as nonuniform definition of the enclosure’s six absorption coefficients. The accuracy of the proposed approximation is demonstrated on the basis of impulse-response simulations involving various room sizes and reverberation levels, with uniform and nonuniform sound absorption coefficients. An application example for the proposed method is illustrated by considering the task of predicting an enclosure’s reflection coefficients in order to achieve a specific reverberation level. The technique presented in this work enables designers to undertake a preliminary analysis of a simulated reverberant environment without the need for time-consuming image-method simulations.

338 citations

BookDOI
01 Mar 1998
TL;DR: There are whole classes of algorithms that the speech community is not interested in pursuing or using in digital signal processing of sound and these algorithms and techniques are revealed in this book.
Abstract: With the advent of `multimedia', digital signal processing (DSP) of sound has emerged from the shadow of bandwidth limited speech processing to become a research field of its own. To date, most research in DSP applied to sound has been concentrated on speech, which is bandwidth limited to about 4 kilohertz. Speech processing is also limited by the low fidelity typically expected in the telephone network. Today, the main applications of audio DSP are high quality audio coding and the digital generation and manipulation of music signals. They share common research topics including perceptual measurement techniques and analysis/synthesis methods. Additional important topics are hearing aids using signal processing technology and hardware architectures for digital signal processing of audio. In all these areas the last decade has seen a significant amount of application-oriented research. The frequency range of wideband audio has an upper limit of 20 kilohertz and the resulting difference in frequency range and Signal to Noise Ratio (SNR) due to sample size must be taken into account when designing DSP algorithms. There are whole classes of algorithms that the speech community is not interested in pursuing or using. These algorithms and techniques are revealed in this book. This book is suitable for advanced level courses and serves as a valuable reference for researchers in the field. Interested and informed engineers will also find the book useful in their work.

300 citations

Proceedings ArticleDOI
24 Jul 1998
TL;DR: This work has developed a system that uses precomputed spatial subdivision and “beam tree” data structures to enable real-time acoustic modeling and auralization in interactive virtual environments and is using this system to develop interactive applications in which a user experiences a virtual environment immersively via simultaneous auralized and visualization.
Abstract: Virtual environment research has focused on interactive image generation and has largely ignored acoustic modeling for spatialization of sound. Yet, realistic auditory cues can complement and enhance visual cues to aid navigation, comprehension, and sense of presence in virtual environments. A primary challenge in acoustic modeling is computation of reverberation paths from sound sources fast enough for real-time auralization. We have developed a system that uses precomputed spatial subdivision and “beam tree” data structures to enable real-time acoustic modeling and auralization in interactive virtual environments. The spatial subdivision is a partition of 3D space into convex polyhedral regions (cells) represented as a cell adjacency graph. A beam tracing algorithm recursively traces pyramidal beams through the spatial subdivision to construct a beam tree data structure representing the regions of space reachable by each potential sequence of transmission and specular reflection events at cell boundaries. From these precomputed data structures, we can generate high-order specular reflection and transmission paths at interactive rates to spatialize fixed sound sources in real-time as the user moves through a virtual environment. Unlike previous acoustic modeling work, our beam tracing method: 1) supports evaluation of reverberation paths at interactive rates, 2) scales to compute highorder reflections and large environments, and 3) extends naturally to compute paths of diffraction and diffuse reflection efficiently. We are using this system to develop interactive applications in which a user experiences a virtual environment immersively via simultaneous auralization and visualization.

250 citations

Journal ArticleDOI
TL;DR: The main principles, landmarks in the development, and state-of-the-art for techniques that are based on geometrical acoustics principles are described.
Abstract: Computerized room acoustics modeling has been practiced for almost 50 years up to date. These modeling techniques play an important role in room acoustic design nowadays, often including auralization, but can also help in the construction of virtual environments for such applications as computer games, cognitive research, and training. This overview describes the main principles, landmarks in the development, and state-of-the-art for techniques that are based on geometrical acoustics principles. A focus is given to their capabilities to model the different aspects of sound propagation: specular vs diffuse reflections, and diffraction.

226 citations

Journal ArticleDOI
TL;DR: An improved parametric model for a spring reverberation unit is presented, which is currently mainly used for simplified geometries or to generate reverberation impulse responses for use with a convolution method.
Abstract: The first artificial reverberation algorithms were proposed in the early 1960s, and new, improved algorithms are published regularly. These algorithms have been widely used in music production since the 1970s, and now find applications in new fields, such as game audio. This overview article provides a unified review of the various approaches to digital artificial reverberation. The three main categories have been delay networks, convolution-based algorithms, and physical room models. Delay-network and convolution techniques have been competing in popularity in the music technology field, and are often employed to produce a desired perceptual or artistic effect. In applications including virtual reality, predictive acoustic modeling, and computer-aided design of acoustic spaces, accuracy is desired, and physical models have been mainly used, although, due to their computational complexity, they are currently mainly used for simplified geometries or to generate reverberation impulse responses for use with a convolution method. With the increase of computing power, all these approaches will be available in real time. A recent trend in audio technology is the emulation of analog artificial reverberation units, such as spring reverberators, using signal processing algorithms. As a case study we present an improved parametric model for a spring reverberation unit.

218 citations