Download Making Sounds with Numbers: A Tutorial on Music Software Dedicated to Digital Audio A (partial) taxonomy of software applications devoted to sounds is presented. For each category of software applications, an abstract model is proposed and actual implementations are evaluated with respect to this model.
Download Fractionally-addressed Delay Lines While traditional implementations of digital delay lines are based on a circular buffer accessed by two pointers, we propose an implementation where a single fractional pointer is used both for reading and writing operations. On modern general-purpose architectures, the proposed method is nearly as efficient as the popular interpolated circular buffer, but it offers better performance in terms of frequency-dependent attenuation and response to delay-length modulations.
Download A generalized 3-d resonator model for simulation of non rectangular shapes A rectangular enclosure has such an even distribution of resonances that it can be accurately modeled using a feedback delay network, but a non rectangular shape such as a sphere has resonances that are distributed according to the extremal points of the spherical Bessel functions. This work proposes an extension of the already known feedback delay network structure to model a non rectangular shape such as a sphere. A speci c frequency distribution of resonances can be approximated, up to a certain frequency, by inserting an allpass lter of moderate order after the delay line within the comb lter structure. The feedback delay network used for rectangular boxes is therefore augmented with a set of allpass lters allowing parametric control over the enclosure size and the boundary properties. This work was motivated by informal listening tests which have shown that it is possible to identify a basic shape just from the distribution of its audible resonances.
Download Using the waveguide mesh in modelling 3D resonators Most of the results found by several researchers, during these years, in physical modelling of two dimensional (2D) resonators by means of waveguide meshes, extend without too much difficulty to the three dimensional (3D) case. Important parameters such as the dispersion error, the spatial bandwidth, and the sampling efficiency, which characterize the behavior and the performance of a waveguide mesh, can be reformulated in the 3D case, giving the possibility to design mesh geometries supported by a consistent theory. A comparison between different geometries can be carried out in a theoretical context. Here, we emphasize the use of the waveguide meshes as efficient tools for the analysis of resonances in 3D resonators of various shapes. For this purpose, several mesh geometries have been implemented into an application running on a PC, provided with a graphical interface that allows an easy input of the parameters and a simple observation of the consequent system evolution and the output data. This application is especially expected to give information on the modes resonating in generic 3D shapes, where a theoretical prediction of the modal frequencies is hard to do.
Download Modeling Collision Sounds: Non-Linear Contact Force A model for physically based synthesis of collision sounds is proposed. Attention is focused on the non-linear contact force, for which both analytical and experimental results are presented. Numerical implementation of the model is discussed, with regard to accuracy and efficiency issues. As an application, a physically based audio effect is presented.
Download Separation Of Speech Signal From Complex Auditory Scenes The hearing system, even in front of complex auditory scenes and in unfavourable conditions, is able to separate and recognize auditory events accurately. A great deal of effort has gone into the understanding of how, after having captured the acoustical data, the human auditory system processes them. The aim of this work is the digital implementation of the decomposition of a complex sound in separate parts as it would appear to a listener. This operation is called signal separation. In this work, the separation of speech signal from complex auditory scenes has been studied and an experimentation of the techniques that address this problem has been done.
Download Recognition Of Ellipsoids From Acoustic Cues Ideal three-dimensional resonators are “labeled” (identified) by infinite sequences of resonance modes, whose distribution depends on the resonator shape. We are investigating the ability of human beings to recognize these shapes by auditory spectral cues. Rather than focusing on a precise simulation of the resonator, we want to understand if the recognition takes place using simplified “cartoon” models, just providing the first resonances that identify a shape. In fact, such models can be easily translated into efficient algorithms for real-time sound synthesis in contexts of human-machine interaction, where the resonator shape and other rendering parameters can be interactively manipulated. This paper describes the method we have followed to come up with an application that, executed in real-time, can be used in listening tests of shape recognition and together with human-computer interfaces.
Download Modeling Interactions between Rubbed Dry Surfaces Using an Elasto-Plastic Friction Model A physically based model of the frictional interaction between dry surfaces is presented. The paper reviews a number of static and dynamic friction models, and discusses numerical techniques for the accurate and efficient numerical implementation of a dynamic elasto-plastic model. An application to the bowed string is provided, and the resulting simulations are compared to recent results from the literature.
Download Recognition of Distance Cues from a Virtual Spatialization Model Emerging issues in the auditory display aim at increasing the usability of interfaces. In this paper we present a virtual resonating environment, which synthesizes distance cues by means of reverberation. We realize a model that recreates the acoustics inside a tube, applying a numerical scheme called Waveguide Mesh, and we present the psychophysical experiments we have conducted for validating the information about distance conveyed by the virtual environment.
Download A Fast Mellin Transform with Applications in DAFx Many digital audio effects rely on transformations performed in the Fourier-transformed (frequency) domain. However, other transforms and domains exist and could be exploited. We propose to use the Mellin transform for a class of sound transformations. We present a fast implementation of the Mellin transform (more precisely a Fast Scale Transform), and we provide some examples on how it could be used in digital audio effects.