Download Transient Encoding of Audio Signals Using Dyadic Approximations In this paper, we present a frame based approach for transient detection and encoding of audio signals. The transient detection procedure, as presented here, uses linear prediction within a signal frame followed by an envelope estimation to build an adaptive threshold. Detected transients will automatically be separated and the gaps left by the removed transient are filled with samples from forward and backward extrapolation. To encode detected transients, dyadic approximation approaches are discussed. Results of the application to different audio signals are also presented.
Download Adjustable Boundary Conditions for Multidimensional Transfer Function Models Block based physical modeling requires to provide a library of modeling blocks for standard components of real or virtual musical instruments. Complex synthesis models are built by connecting standard components in a physically meaningful way. These connections are investigated for modeling a resonating structure as a distributed parameter system. The dependence of a resonator’s spectral structure on the termination of its ports is analyzed. It is shown that the boundary conditions of a distributed parameter system can be adjusted by proper termination only. Examples show the corresponding variation of the resonator’s spectral structure in response to variations of the external termination.
Download Self-Sustained Vibrating Structures Physical Modelling by Means of Mass-Interaction Networks GENESIS is a sound synthesis and musical creation environment based on the mass-interaction CORDIS-ANIMA physical modelling formalism. It has got the noteworthy property that it allows to work both on sound itself and on musical composition in a single coherent environment. In this paper we present the first results of a study that is carried out with GENESIS on a particular type of models: self-sustained oscillating structures. By trying to build physical models of real instruments like bowed strings or woodwinds, our aim is to develop and analyse generic tools that can be used for the production of self-sustained oscillations on every mass-interaction network built with GENESIS. But, if the family of the self-sustained oscillating structures is very interesting to create rich timbres, it can also play a new and fundamental role at the level of the temporal macrostructure of the music (that of the gesture and the instrumental performance, as well as the composition). Indeed, it is possible, as we will propose in this paper, to use the relatively complex motion of a bowed macrostructure in a musical composition way, as a musical events generator.
Download Filtering within the Framework of Mass-Interaction Physical Modeling and of Haptic Gestural Interaction A variety of filters have been designed, synthesized and used in the history of electronic and computer music. All the approaches aimed to provide filters fulfilling several specifications such as frequency response, phase response, transient state characteristics like rise time and overshoot, realizably conditions concerning the technology used for the implementation and even economical considerations. One of the most important aspects concerning the filters dedicated to musical applications is the control structure they provide to the musician, who is in charge for the integration of the filtering operation in the compositional process and performance. Designing filters using the mass interaction scheme embedded in the CORDIS-ANIMA formalism (used for sound synthesis and composition by physical modelling) offers a different methodology in the control which is coherent with the philosophy of musical composition by ‘physical thinking’. This article introduces a technique to design filters using the CORDIS-ANIMA simulation language.
Download 3D interactive environment for music collection navigation Previous interfaces for large collections of music have used spatial audio to enhance the presentation of a visual interface or to add a mode of interaction. An interface using only audio information is presented here as a means to explore a large music collection in a two or three-dimensional space. By taking advantage of Ambisonics and binaural technology, the application presented here can scale to large collections, have flexible playback requirements, and can be optimized for slower computers. User evaluation reveals issues in creating an intuitive mapping between between user movements in physical space and virtual movement through the collection, but the novel presentation of the music collection has positive feedback and warrants further development.
Download Simulating guitar distortion circuits using wave digital and nonlinear state-space formulations This work extends previous research on numerical solution of nonlinear systems in musical acoustics to the realm of nonlinear musical circuits. Wave digital principles and nonlinear state-space simulators provide two alternative approaches explored in this work. These methods are used to simulate voltage amplification stages typically used in guitar distortion or amplifier circuits. Block level analysis of the entire circuit suggests a strategy based upon the nonlinear filter composition technique for connecting amplifier stages while accounting for the way these stages interact. Formulations are given for the bright switch, the diode clipper, a transistor amplifier, and a triode amplifier.
Download A modified FM synthesis approach to bandlimited signal generation Techniques for the generation of bandlimited signals for application to digital implementations of subtractive synthesis have been researched by a number of authors. This paper hopes to contribute to the variety of approaches by proposing a technique based on Frequency Modulation (FM) synthesis. This paper presents and explains the equations required for bandlimited pulse generation using modified FM synthesis. It then investigates the relationships between the modulation index and the quality of the reproduction in terms of authenticity and aliasing for a sawtooth wave. To determine the performance of this technique in comparison to others two sets of simulation results are offered: the first computes the relative power of the non-harmonic components, and the second uses the Perceptual Evaluation of Audio Quality (PEAQ) algorithm. It is shown that this technique compares well with the alternatives. The paper concludes with suggestions for the direction of future improvements to the method.
Download A nonlinear digital model of the EMS VCS3 voltage-controlled filter This article presents a nonlinear discrete-time model of the EMS VCS3 voltage-controlled filters. The development of the model is based on the study of the filter circuitry and its behavior in the time domain. From this circuitry a system of nonlinear differential equations has been derived describing the dynamics in regime of large signals. The digital implementation of the filter is based on a numerical approximation of those equations. The resulting Matlab model has been compared with a structurally identical simulation running under PSpice. Finally, a real-time realization of the VCF has been implemented under the Pure Data processing environment.
Download Quality estimation of time-scale modified signals The paper describes some properties and problems related to Perceptual Evaluation of Speech Quality (PESQ) delay compensation mechanism and relations between time-scale modification and quality estimate. The evaluation of PESQ algorithm with two types of signal stretching (uniform resampling-based stretch and pitch-preserving stretch) was performed and the listening tests with human listeners were carried out. PESQ performance was also compared against the 3SQM algorithm. Experimental results indicate that performance of PESQ is not sufficient for high precision quality estimation of time-scale distortions.