Download High-level musical control paradigms for Digital Signal Processing No matter how complex DSP algorithms are and how rich sonic processes they produce, the issue of their control immediately arises when they are used by musicians, independently on their knowledge of the underlying mathematics or their degree of familiarity with the design of digital instruments. This text will analyze the problem of the control of DSP modules from a compositional standpoint. An implementation of some paradigms in a Lisp-based environment (omChroma) will also be concisely discussed.
Download Pinna Morphological Parameters Influencing HRTF Sets Head-Related Transfer Functions (HRTFs) are one of the main aspects of binaural rendering. By definition, these functions express the deep linkage that exists between hearing and morphology especially of the torso, head and ears. Although the perceptive effects of HRTFs is undeniable, the exact influence of the human morphology is still unclear. Its reduction into few anthropometric measurements have led to numerous studies aiming at establishing a ranking of these parameters. However, no consensus has yet been set. In this paper, we study the influence of the anthropometric measurements of the ear, as defined by the CIPIC database, on the HRTFs. This is done through the computation of HRTFs by Fast Multipole Boundary Element Method (FM-BEM) from a parametric model of torso, head and ears. Their variations are measured with 4 different spectral metrics over 4 frequency bands spanning from 0 to 16kHz. Our contribution is the establishment of a ranking of the selected parameters and a comparison to what has already been obtained by the community. Additionally, a discussion over the relevance of each approach is conducted, especially when it relies on the CIPIC data, as well as a discussion over the CIPIC database limitations.
Download Towards Efficient Emulation of Nonlinear Analog Circuits for Audio Using Constraint Stabilization and Convex Quadratic Programming This paper introduces a computationally efficient method for
the emulation of nonlinear analog audio circuits by combining state-space representations, constraint stabilization, and convex quadratic programming (QP). Unlike traditional virtual analog (VA) modeling approaches or computationally demanding
SPICE-based simulations, our approach reformulates the nonlinear
differential-algebraic (DAE) systems that arise from analog circuit
analysis into numerically stable optimization problems. The proposed method efficiently addresses the numerical challenges posed
by nonlinear algebraic constraints via constraint stabilization techniques, significantly enhancing robustness and stability, suitable
for real-time simulations. A canonical diode clipper circuit is presented as a test case, demonstrating that our method achieves accurate and faster emulations compared to conventional state-space
methods. Furthermore, our method performs very well even at
substantially lower sampling rates. Preliminary numerical experiments confirm that the proposed approach offers improved numerical stability and real-time feasibility, positioning it as a practical
solution for high-fidelity audio applications.
Download Extensions and Applications of Modal Dispersive Filters Dispersive delay and comb filters, implemented as a parallel sum of high-Q mode filters tuned to provide a desired frequency-dependent delay characteristic, have advantages over dispersive filters that are implemented using cascade or frequency-domain architectures. Here we present techniques for designing the modal filter parameters for music and audio applications. Through examples, we show that this parallel structure is conducive to interactive and time-varying modifications, and we introduce extensions to the basic model.
Download Wave Field Synthesis - Generation and Reproduction of Natural Sound Environments Since the early days of stereo good spatial sound impression had been limited to a small region, the so-called sweet spot. About 15 years ago the concept of wave field synthesis (WFS) solving this problem has been invented at TU Delft, but due to its computational complexity it has not been used outside universities and research institutes. Today the progress of microelectronics makes a variety of applications of WFS possible, like themed environments, cinemas, and exhibition spaces. This paper will highlight the basics of WFS and discuss some of the solutions beyond the basics to make it work in applications.
Download EVERTims: Open Source Framework for Real-time Auralization in Architectural Acoustics and Virtual Reality This paper presents recent developments of the EVERTims project, an auralization framework for virtual acoustics and real-time room acoustic simulation. The EVERTims framework relies on three independent components: a scene graph editor, a room acoustic modeler, and a spatial audio renderer for auralization. The framework was first published and detailed in [1, 2]. Recent developments presented here concern the complete re-design of the scene graph editor unit, and the C++ implementation of a new spatial renderer based on the JUCE framework. EVERTims now functions as a Blender add-on to support real-time auralization of any 3D room model, both for its creation in Blender and its exploration in the Blender Game Engine. The EVERTims framework is published as open source software: http://evertims.ircam. fr.
Download Flexible Real-Time Reverberation Synthesis With Accurate Parameter Control Reverberation is one of the most important effects used in audio
production. Although nowadays numerous real-time implementations of artificial reverberation algorithms are available, many of
them depend on a database of recorded or pre-synthesized room
impulse responses, which are convolved with the input signal. Implementations that use an algorithmic approach are more flexible
but do not let the users have full control over the produced sound,
allowing only a few selected parameters to be altered. The realtime implementation of an artificial reverberation synthesizer presented in this study introduces an audio plugin based on a feedback delay network (FDN), which lets the user have full and detailed insight into the produced reverb. It allows for control of
reverberation time in ten octave bands, simultaneously allowing
adjusting the feedback matrix type and delay-line lengths. The
proposed plugin explores various FDN setups, showing that the
lowest useful order for high-quality sound is 16, and that in the
case of a Householder matrix the implementation strongly affects
the resulting reverberation. Experimenting with delay lengths and
distribution demonstrates that choosing too wide or too narrow a
length range is disadvantageous to the synthesized sound quality.
The study also discusses CPU usage for different FDN orders and
plugin states.
Download Pywdf: An Open Source Library for Prototyping and Simulating Wave Digital Filter Circuits in Python This paper introduces a new open-source Python library for the modeling and simulation of wave digital filter (WDF) circuits. The library, called pwydf, allows users to easily create and analyze WDF circuit models in a high-level, object-oriented manner. The library includes a variety of built-in components, such as voltage sources, capacitors, diodes etc., as well as the ability to create custom components and circuits. Additionally, pywdf includes a variety of analysis tools, such as frequency response and transient analysis, to aid in the design and optimization of WDF circuits. We demonstrate the library’s efficacy in replicating the nonlinear behavior of an analog diode clipper circuit, and in creating an allpass filter that cannot be realized in the analog world. The library is well-documented and includes several examples to help users get started. Overall, pywdf is a powerful tool for anyone working with WDF circuits, and we hope it can be of great use to researchers and engineers in the field.
Download Towards Ontological Representations of Digital Audio Effects In this paper we discuss the development of ontological representations of digital audio effects and provide a framework for the description of digital audio effects and audio effect transformations. After a brief account on our current research in the field of highlevel semantics for music production using Semantic Web technologies, we detail how an Audio Effects Ontology can be used within the context of intelligent music production tools, as well as for musicological purposes. Furthermore, we discuss problems in the design of such an ontology arising from discipline-specific classifications, such as the need for encoding different taxonomical systems based on, for instance, implementation techniques or perceptual attributes of audio effects. Finally, we show how information about audio effect transformations is represented using Semantic Web technologies, the Resource Description framework (RDF) and retrieved using the SPARQL query language.
Download Fractal Modulation Effects Fractal modulation is obtained by forming a power weighted superposition of scaled and modulated versions of the signal. The resulting signal is self-similar with fractal characteristics. In this paper we explore fractal modulation as a powerful method to generate rich signals, useful both for the synthesis of complex sounds, like the sounds from natural events or ecological sounds, or as control functions of audio effects. The wavelet transform can be used as an efficient tool in order to generate a subset of fractal modulated signals that are power homogeneous. Any signal used as a seed for fractal modulation is transformed into a multiscale sound by means of a tree-structured multirate filter bank. Moreover, by superimposing a structured modulation scheme one can generate pseudo-periodic sounds whose partials have fractal behavior.