Davide Rocchesso

Continuous sonic feedback from a rolling ball

Balancing a ball along a tillable track is a control metaphor for a variety of continuous control tasks. The authors designed the Ballancer experimental tangible interface to exploit such a metaphor. Direct, model-based sonification of the rolling ball improves the experience and effectiveness of the interaction.

Sounding objects

Interactive systems, virtual environments, and information display applications need dynamic sound models rather than faithful audio reproductions. This implies three levels of research: auditory perception, physics-based sound modeling, and expressive parametric control. Parallel progress along these three lines leads to effective auditory displays that can complement or substitute visual displays. This article aims to shed some light on how psychologists, computer scientists, acousticians, and engineers can work together and address these and other questions arising in sound design for interactive multimedia systems.

Circulant and elliptic feedback delay networks for artificial reverberation

The feedback delay network (FDN) has been proposed for digital reverberation, The digital waveguide network (DWN) is also proposed with similar advantages. This paper notes that the commonly used FDN with an N/spl times/N orthogonal feedback matrix is isomorphic to a normalized digital waveguide network consisting of one scattering junction joining N reflectively terminated branches. Generalizations of FDNs and DWNs are discussed. The general case of a lossless 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 audio signal processing are discussed.

Elimination of delay-free loops in discrete-time models of nonlinear acoustic systems

Nonlinear acoustic systems are often described by means of nonlinear maps acting as instantaneous constraints on the solutions of a system of linear differential equations. This description leads to discrete-time models exhibiting noncomputable loops. We present a solution to this computability problem by means of geometrical transformation of the nonlinearities and algebraic transformation of the time-dependent equations. The proposed solution leads to stable and accurate simulations even at relatively low sampling rates.

Interactive Simulation of rigid body interaction with friction-induced sound generation

Acoustic simulation of friction is a particularly challenging task, because continuous (strong) contact conditions require a tight and veridical integration of the synthesis layer with the control input. This paper presents an algorithmic realization that combines recently proposed physical models of friction with the lumped modal description of resonating bodies. It is shown that the resulting nonlinear dynamical system can be discretized using a numerical technique that allows efficient and accurate simulation. Applications in the context of interactive audio-visual animation on low-cost general-purpose computers are demonstrated, and an approach to joint audio-visual synthesis is proposed that provides fine-scale synchronization and high coherence between the two modalities. The interactive animations show that the model is successful in reproducing several salient everyday sound phenomena, such as rubbing, braking, and squeaky doors.

Signal-theoretic characterization of waveguide mesh geometries for models of two-dimensional wave propagation in elastic media

Waveguide meshes are efficient and versatile models of wave propagation along a multidimensional ideal medium. The choice of the mesh geometry affects both the computational cost and the accuracy of simulations. In this paper, we focus on two-dimensional (2-D) geometries and use multidimensional sampling theory to compare the square, triangular, and hexagonal meshes in terms of sampling efficiency and dispersion error under conditions of critical sampling. The analysis shows that the triangular geometry exhibits the most desirable tradeoff between accuracy and computational cost.

A fast Mellin and scale transform

A fast algorithm for the discrete-scale (and-Mellin) transform is proposed. It performs a discrete-time discrete-scale approximation of the continuous-time transform, with subquadratic asymptotic complexity. The algorithm is based on a well-known relation between the Mellin and Fourier transforms, and it is practical and accurate. The paper gives some theoretical background on the Mellin,-Mellin, and scale transforms. Then the algorithm is presented and analyzed in terms of computational complexity and precision. The effects of different interpolation procedures used in the algorithm are discussed.

Integration of Acoustical Information in the Perception of Impacted Sound Sources: The Role of Information Accuracy and Exploitability

Sound sources are perceived by integrating information from multiple acoustical features. The factors influencing the integration of information are largely unknown. We measured how the perceptual weighting of different features varies with the accuracy of information and with a listeners ability to exploit it. Participants judged the hardness of two objects whose interaction generates an impact sound: a hammer and a sounding object. In a first discrimination experiment, trained listeners focused on the most accurate information, although with greater difficulty when perceiving the hammer. We inferred a limited exploitability for the most accurate hammer-hardness information. In a second rating experiment, listeners focused on the most accurate information only when estimating sounding-object hardness. In a third rating experiment, we synthesized sounds by independently manipulating source properties that covaried in Experiments 1 and 2: sounding-object hardness and impact properties. Sounding-object hardness perception relied on the most accurate acoustical information, whereas impact-properties influenced more strongly hammer hardness perception. Overall, perceptual weight increased with the accuracy of acoustical information, although information that was not easily exploited was perceptually secondary, even if accurate.

Physically informed signal processing methods for piano sound synthesis: a research overview

This paper reviews recent developments in physics-based synthesis of piano. The paper considers the main components of the instrument, that is, the hammer, the string, and the soundboard. Modeling techniques are discussed for each of these elements, together with implementation strategies. Attention is focused on numerical issues, and each implementation technique is described in light of its efficiency and accuracy properties. As the structured audio coding approach is gaining popularity, the authors argue that the physical modeling approach will have relevant applications in the field of multimedia communication.

A toolkit for explorations in sonic interaction design

Physics-based sound synthesis represents a promising paradigm for the design of a veridical and effective continuous feedback in augmented everyday contexts. In this paper, we introduce the Sound Design Toolkit (SDT), a software package available as a complete front-end application, providing a palette of virtual lutheries and foley pits, that can be exploited in sonic interaction design research and education. In particular, the package includes polyphonic features and connectivity to multiple external devices and sensors in order to facilitate the embedding of sonic attributes in interactive artifacts. The present release represents an initial version towards an effective and usable tool for sonic interaction designers.