Animations for which sound effects were automatically added by our system, demonstrated in the accompanying video. (a) A real wok in which a pebble is thrown; the pebble rattles around the wok and comes to rest after wobbling. (b) A simulation of a pebble thrown in wok, with all sound effects automatically generated. (c) A ball rolling back and forth on a ribbed surface. (d) Interaction with a sonified object. We describe algorithms for real-time synthesis of realistic sound effects for interactive simulations (e.g., games) and animation. These sound effects are produced automatically, from 3D models using dynamic simulation and user interaction. We develop algorithms that are efficient, physicallybased, and can be controlled by users in natural ways. We develop effective techniques for producing high quality continuous contact sounds from dynamic simulations running at video rates which are slow relative to audio synthesis. We accomplish this using modal models driven by contact forces modeled at audio rates, which are much higher than the graphics frame rate. The contact forces can be computed from simulations or can be custom designed. We demonstrate the effectiveness with complex realistic simulations.

The Theremin was one of the first electronic musical instruments, yet it provides a degree of expressive real-time control that remains lacking in most modern electronic music interfaces. Underlying the deceptively simple capacitance measurement used by it and its descendants are a number of surprisingly interesting current transport mechanisms that can be used to inexpensively, unobtrusively, robustly, and remotely detect the position of people and objects. We review the relevant physics, describe appropriate measurement instrumentation, and discuss applications that began with capturing virtuosic performance gesture on traditional stringed instruments and evolved into the design of new musical interfaces. 1)

An extremely efficient method for modeling wave propagation in a membrane is provided by the multidimensional extension of the digital waveguide. The 2-D digital waveguide mesh is constructed out of bidirectional delay units and scattering junctions. We show that it coincides with the standard finite difference approximation scheme for the 2-D wave equation, and we derive the dispersion error. Applications may be found in physical models of drums, soundboards, cymbals, gongs, small-box reverberators, and other acoustic constructs where a one-dimensional model is less desirable. 1 Background Theory There are many musical applications of the onedimensional digital waveguide ranging from the generation of wind and string instrument tones, to flanging effects [Van Duyne and Smith, 1992], to reverberation [Smith, 1987]. We review the theoretical derivation of one-dimensional traveling waves as a basis for development of the twodimensional digital waveguide mesh. 1.1 The 1-D Wave Equation...

Sonification is the use of non-speech audio to convey information. We are developing tools for interactive data exploration, which make use of sonification for data presentation. In this paper, model-based sonification is presented as a concept to design auditory displays. Two designs are described: (1) particle trajectories in a "data potential" is a sonification model to reveal information about the clustering of vectorial data and (2) "data-sonograms" is a sonification for data from a classification problem to reveal information about the mixing of distinct classes.

In this paper we present a graphical model for polyphonic music transcription. Our model, formulated as a Dynamical Bayesian Network, embodies a transparent and computationally tractable approach to this acoustic analysis problem. An advantage of our approach is that it places emphasis on explicitly modelling the sound generation procedure. It provides a clear framework in which both high level (cognitive) prior information on music structure can be coupled with low level (acoustic physical) information in a principled manner to perform the analysis. The model is a special case of the, generally intractable, switching Kalman filter model. Where possible, we derive, exact polynomial time inference procedures, and otherwise efficient approximations. We argue that our generative model based approach is computationally feasible for many music applications and is readily extensible to more general auditory scene analysis scenarios.

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The feedback delay network (FDN) has been proposed for digital reverberation. Also proposed with similar advantages is the digital waveguide network (DWN). This paper notes that the commonly used FDN with an N × N orthogonal feedback matrix is isomorphic to a normalized digital waveguide network consisting of one scattering junction and a vector transformer joining N reflectively terminated branches. Generalizations of FDNs and DWNs are discussed. The general case of a losslessness FDN feedback matrix is shown to be any matrix having unit-modulus eigenvalues and linearly independent eigenvectors. A special class of FDNs using circulant matrices is proposed. These structures can be efficiently implemented and allow control of the time and frequency behavior. Applications of circulant feedback delay networks in

sical instruments, such as strings and flutes [Smith 1992]. Two-dimensional (2D) and threedimensional (3D) extensions of waveguides have been proposed for simulation of plates and drums [Van Duyne and Smith 1993]. A 3D mesh is needed for modeling the vibrations of air in a room [Savioja et al. 1994]. A higher-dimensional waveguide mesh is a regular array of 1-D waveguides arranged along each perpendicular dimension, interconnected at their crossings. Two conditions must be satisfied at a lossless junction connecting lines of equal impedance: (1) the sum of inputs equals the sum of outputs (flows add to zero) and (2) the signals in each crossing waveguide are equal at the junction (continuity of impedances). Based on these a difference equation can be derived for the nodes of an N-dimensional rectangular mesh: where represents in this application the signal pressure (in this application) at a junction at time step n, k is the position of the junction to be

Efficient physical models of bar percussion instruments which preserve spatial sampling are not yet available. In this paper, banded waveguides are proposed as an efficient method for simulating the physics of bars including spatial sampling. In addition two other models are investigated. One is a generalization of the waveguide idea replacing unit delays by all-pass filters modeling the phase delay characteristics. The other extends on existing finite difference (FD) methods. According to this study all-pass filter chains show no advantages over FDs in terms of performance and physical realism. Finally, real bars were the target of experimental measurements.

: This paper considers discrete-time allpass filters that implement a time-varying fractional delay. These recursive filters are desirable from the point of view of implementational efficiency and flat magnitude response, but they are prone to transient effects when their parameters are changed. A state variable update approach to this problem is reviewed, the basic idea of which is to modify also the state of the filter when coefficients are changed so that the filter enters a new state smoothly without transient attacks. This method is adapted to give a new and simple practical method for eliminating the transients. The effectiveness of the new technique is verified by applying it to a digital waveguide model of a vibrating string. 1. INTRODUCTION A fractional delay (FD) filter is a device for implementing a noninteger delay, a process equivalent to bandlimited interpolation between samples. FD filters are of fundamental importance in digital waveguide models of musical instruments....