Download Exponential Weighting Method for Sample-by-Sample Update of Warped AR-Model Auto-regressive (AR) modeling is a powerful tool having many ap plications in audio signal processing. The modeling procedure can be focused to low or high frequency range using frequency warp ing. Conventionally the AR-modeling procedure is accomplished with frame-by-frame processing which introduces latency. As with any frame-by-frame algorithm full frame has to be available for the algorithm before any output can be produced. This latency makes AR-modeling more or less unusable in real-time sound effects es pecially when long frame lengths are required. In this paper we introduce an exponential weighting (EW) method for sample-bysample update of the warped AR-model. This method reduces the latency down to the order of the AR-model.
Download Fixed-rate Modeling of Audio Lumped Systems: A Comparison Between Trapezoidal and Implicit Midpoint Methods This paper presents a comparison framework to study the relative benefits of the typical trapezoidal method with the lesser-used implicit midpoint method for the simulation of audio lumped systems at a fixed rate. We provide preliminary tools for understanding the behavior and error associated with each method in connection with typical analysis approaches. We also show implementation strategies for those methods, including how an implicit midpoint method solution can be generated from a trapezoidal method solution and vice versa. Finally, we present some empirical analysis of the behavior of each method for a simple diode clipper circuit and provide an approach to help interpret their relative performance and how to pick the more appropriate method depending on desirable properties. The presented tools are also intended as a general approach to interpret the performance of discretization approaches at large in the context of fixed-rate simulation.
Download The Sounds of the Avian Syrinx - are they Really Flute-Like? This research presents a model of the avian vocal tract, implemented using classical waveguide synthesis and numerical methods. The vocal organ of the songbird, the syrinx, has a unique topography of acoustic tubes (a trachea with a bifurcation at its base) making it a rather unique subject for waveguide synthesis. In the upper region of the two bifid bronchi lies a nonlinear vibrating membrane – the primary resonator in sound production. Unlike most reed musical instruments, the more significant displacement of the membrane is perpendicular to the directions of airflow, due to the Bernoulli effect. The model of the membrane displacement, and the resulting pressure through the constriction created by the membrane motion, is therefore derived beginning with the Bernoulli equation.
Download Morph: Timbre Hybridization Tools Based on Frequency Domain Processing This paper presents a hybridization method using Morph, a sound timbre hybridization and modeling software running on the Windows 95 platform. Elaboration occurs in Fourier space and is based on analysis/re-synthesis operations through FFT and FFT-1. The hybridization method works through the segmentation of two starting spectra in zones centered on the energy peaks. Each identified spectral zone, is numbered in increasing order so that a matching can be established between pairs of zones with the same value during re-synthesis. A full description of the Morph elaboration performance includes cross-synthesis, timbre hybridization, harmonic/inharmonic component separation and filtering. An initial catalogue of hybrid sounds has been compiled using this system, in order to tackle hybridization problems in an organic and systematic manner. The criteria used for the drafting and organization of the catalogue are discussed in the latter part of this paper.
Download Low-Cost Geometry-Based Acoustic Rendering In this paper we propose a new sound rendering algorithm that allows the listener to move within a dinamic acoustic environment. The main goal of this work is to implement a real-time sound rendering software for Virtal Reality applications, which runs on lowcost platforms. The resulting numeric structure is a recursive filter able to efficiently simulate the impulse response of a large room.
Download Non-Iterative Schemes for the Simulation of Nonlinear Audio Circuits In this work, a number of numerical schemes are presented in the
context of virtual-analog simulation. The schemes are linearlyimplicit in character, and hence directly solvable without iterative
methods. Schemes of increasing order of accuracy are constructed,
and convergence and stability conditions are proven formally. The
schemes are able to handle stiff problems very efficiently, because
of their fast update, and can be run at higher sample rates to reduce
aliasing. The cases of the diode clipper and ring modulator are
investigated in detail, including several numerical examples.
Download Quality Diversity for Synthesizer Sound Matching It is difficult to adjust the parameters of a complex synthesizer to
create the desired sound. As such, sound matching, the estimation of synthesis parameters that can replicate a certain sound, is
a task that has often been researched, utilizing optimization methods such as genetic algorithm (GA). In this paper, we introduce a
novelty-based objective for GA-based sound matching. Our contribution is two-fold. First, we show that the novelty objective is
able to improve the quality of sound matching by maintaining phenotypic diversity in the population. Second, we introduce a quality diversity approach to the problem of sound matching, aiming
to find a diverse set of matching sounds. We show that the novelty objective is effective in producing high-performing solutions
that are diverse in terms of specified audio features. This approach
allows for a new way of discovering sounds and exploring the capabilities of a synthesizer.
Download Emulating Rough and Growl Voice in Spectral Domain This paper presents a new approach on transforming a modal voice into a rough or growl voice. The goal of such transformations is to be able to enhance voice expressiveness in singing voice productions. Both techniques work with spectral models and are based on adding sub-harmonics in frequency domain to the original input voice spectrum.
Download CA: A system for Granular Processing of Sound using Cellular Automata is a tool for the granular processing of sound using cellular automata developed on the SGI-Indy platform. It investigates the effects of change in the timbre of sound using a cellular automaton in real-time. The cellular automaton generated by the chosen rule controls parameters of a bank of filters. The system uses standard infinite impulse response filters and a general model of three neighborhood cellular automata. The composer1 can configure the filter banks by adjusting bandwidths and center frequencies through the graphical interface. CA is very well suited as a tool for computer music composition because it is capable of creating a new palette of sounds for the composer and it is easy to use.
Download Multiresolution Sinusoidal/Stochastic Model For Voiced-Sounds The goal of this paper is to introduce a complete analysis/resynthesis method for the stationary part of voiced-sounds. The method is based on a new class of wavelets, the Harmonic-Band Wavelets (HBWT). Wavelets have been widely employed in signal processing [1, 2]. In the context of sound processing they provided very interesting results in their first harmonic version: the Pitch Synchronous Wavelets Transform (PSWT) [3]. We introduced the Harmonic-Band Wavelets in a previous edition of the DAFx [4]. The HBWT, with respect to the PSWT allows one to manipulate the analysis coefficients of each harmonic independently. Furthermore one is able to group the analysis coefficients according to a finer subdivision of the spectrum of each harmonic, due to the multiresolution analysis of the wavelets. This allows one to separate the deterministic components of voiced sounds, corresponding to the harmonic peaks, from the noisy/stochastic components. A first result was the development of a parametric representation of the HBWT analysis coefficients corresponding to the stochastic components [5, 7]. In this paper we present the results concerning a parametric representation of the HBWT analysis coefficients of the deterministic components. The method recalls the sinusoidal models, where one models time-varying amplitudes and time varying phases [8, 9]. This method provides a new interesting technique for sound synthesis and sound processing, integrating a parametric representation of both the deterministic and the stochastic components of sounds. At the same time it can be seen as a tool for a parametric representation of sound and data compression.