Download Creating Music by Means of ´Physical Thinking`: The Musician Oriented Genesis Environment
Mass-interaction physical modeling scheme is often cited as the traditional physical modeling technique, but surprisingly some of the possibilities for musical creation it allows have not yet been pointed out. GENESIS is a graphical environment based on the CORDIS-ANIMA mass-interaction paradigm and designed for musicians. It was conceived so as to help the user "think physical"; that is, to discover and experiment with new ways of creating music, which is necessary when using physical modeling. The paper introduces version 1.5 of the GENESIS environment. Its major features and ergonomic aspects are exposed – especially model representation, low and high level modeling tools, multisensorial simulation facilities. Examples of composer's works are presented.
Download On the Nonlinear Commuted Synthesis of the Piano
In this paper a novel method is presented for the physics-based sound synthesis of the piano, based on digital waveguides. The approach combines the advantages of the commuted synthesis technique and the methods using a nonlinear hammer model. The interaction force of the hammer-string contact is computed by an auxiliary digital waveguide connected to a nonlinear hammer model. This force signal is used as a target impulse response for designing a low-order digital filter real-time. The piano sound is calculated by filtering the soundboard response with the hammer filter and feeding this signal to a synthesizer digital waveguide. A new method is presented for separating the contribution of the interaction force and the soundboard in measured piano tones. For modeling beating, a new technique is proposed based on a simplified pitch-shift effect. Considerations on modeling the effect of sustain pedal are also given. It is shown that the technique of designing the hammer filter real-time is not only useful for digital waveguide modeling, but it can be combined with sampling synthesis too.
Download Efficient Modeling and Synthesis of Bell-like Sounds
This paper describes two different techniques that can be used to model and synthesize bell-like sounds. The first one is a sourcefilter model based on frequency-zooming ARMA (pole-zero) modeling techniques. The frequency-zooming approach is powerful also in modal analysis of bell sound behavior. The second technique is based on a digital waveguide with a single loop filter that is designed to generate inharmonic partials by including one or more second-order allpass sections in the loop filter, possibly augmented with one or a few parallel resonators. A small handbell with inharmonic partials was recorded and used as a target of modeling and synthesis. Sound examples are found in http://www.acoustics.hut.fi/demos/dafx02/.
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 Timbre Morphing using the Modal Distribution
We present techniques for timbre morphing between two audio signals based on the Modal distribution time-frequency representation of music signals. A signal synthesis method is described which resynthesises signals from Modal distributions. Direct resynthesis from the original signal produces a timbre that is almost indistinguishable from the source. In deciding which salient features to morph a relational graph representation of timbre is used and linear interpolation and non-linear warping are applied in performing the morph between Modal distributions.
Download Smoothing of the Control Signal without Clipped Output in Digital Peak Limiters
This paper studies the reduction of nonlinearity of digital peak limiters used for maximizing signal levels. The goal is to control the time-varying gain smoothly enough to avoid frequency artifacts in the output signal. Smoother gain control is traditionally obtained by lowpass Þltering the gain or the signal envelope. However, simple Þltering causes overshoots and leads to either clipped output or non-maximal signal levels, depending on the gain applied to the limiter output. In order to obtain smooth gain control without clipping, this paper proposes an envelope detection method based on order-statistics Þltering.
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 A Measurement Technique for Highly Nonlinear Transfer Functions
This paper presents a new method to estimate nonlinear transfer functions of tube amplifiers or distortion effect stages. A special test signal and a sorting algorithm allow the calculation of the nonlinear transfer functions. PSPICE simulations of a tube amplifier as well as real-time measurements of a tube amplifier with a high quality 24bit/96kHz sound card will be presented.
Download Performance Analysis of a Source Separation Algorithm
Source separation is an attractive preprocessing step for applying digital audio effects to a single source inside a signal mix. We present a performance analysis of a source separation algorithm based on time-frequency processing and its application to digital audio effects. The performance analysis gives insight to the main analysis parameters for the detection of the number of source signals inside the signal mix. We also analyze the main design parameters for the demixing operation which extracts a single source out of the signal mix.
Download Audio Signal Processing and Object-oriented Systems
Object-oriented programming (OOP) has been for many years now one of the most important programming paradigms used in a variety of applications. Digital audio signal processing can benefit largely from this approach for systems development. In this paper a number of approaches to using object-orientation in audio processing systems are reviewed. Existing systems of audio processing are introduced and discussed in detail. The paper also draws attention to the different OOP techniques enabled and supported by these systems. Comparative code and tutorial examples are included, providing an insight into the development of signal processing applications using objects.