Download Morphing of granular sounds Granular sounds are commonly used in video games but the conventional approach of using recorded samples does not allow sound designers to modify these sounds. In this paper we present a technique to synthesize granular sound whose tone color lies at an arbitrary point between two given granular sound samples. We first extract grains and noise profiles from the recordings, morph between them and finally synthesize sound using the morphed data. During sound synthesis a number of parameters, such as the number of grains per second or the loudness distribution of the grains, can be altered to vary the sound. The proposed method does not only allow to create new sounds in real-time, it also drastically reduces the memory footprint of granular sounds by reducing a long recording to a few hundred grains of a few milliseconds length each.
Download Reverberation still in business: Thickening and Propagating micro-textures in physics-based sound modeling Artificial reverberation is usually introduced, as a digital audio effect, to give a sense of enclosing architectural space. In this paper we argue about the effectiveness and usefulness of diffusive reverberators in physically-inspired sound synthesis. Examples are given for the synthesis of textural sounds, as they emerge from solid mechanical interactions, as well as from aerodynamic and liquid phenomena.
Download Granular analysis/synthesis of percussive drilling sounds This paper deals with the automatic and robust analysis, and the realistic and low-cost synthesis of percussive drilling like sounds. The two contributions are: a non-supervised removal of quasistationary background noise based on the Non-negative Matrix Factorization, and a granular method for analysis/synthesis of this drilling sounds. These two points are appropriate to the acoustical properties of percussive drilling sounds, and can be extended to other sounds with similar characteristics. The context of this work is the training of operators of working machines using simulators. Additionally, an implementation is explained.
Download Feature design for the classification of audio effect units by input/output measurements Virtual analog modeling is an important field of digital audio signal processing. It allows to recreate the tonal characteristics of real-world sound sources or to impress the specific sound of a certain analog device upon a digital signal on a software basis. Automatic virtual analog modeling using black-box system identification based on input/output (I/O) measurements is an emerging approach, which can be greatly enhanced by specific pre-processing methods suggesting the best-fitting model to be optimized in the actual identification process. In this work, several features based on specific test signals are presented allowing to categorize instrument effect units into classes of effects, like distortion, compression, modulations and similar categories. The categorization of analog effect units is especially challenging due to the wide variety of these effects. For each device, I/O measurements are performed and a set of features is calculated to allow the classification. The features are computed for several effect units to evaluate their applicability using a basic classifier based on pattern matching.
Download Real-time 3D Ambisonics using Faust, Processing, Pure Data, and OSC This paper presents several digital signal processing (DSP) tools for the real-time synthesis of a 3D sound pressure field using Ambisonics technologies. The spatialization of monophonic signal or the reconstruction of natural 3D recorded sound pressure fields is considered. The DSP required to generate the loudspeaker signals is implemented using the FAUST programming language. FAUST enables and simplifies the compilation of the developed tools on several architectures and on different DSP tool format. In this paper, a focus is made on the near-field filters implementation which allows for the encoding of spherical waves with distance information. The gain variation with distance is also taken into account. The control of the synthesis can be made by software controllers or hardware controllers, such as joystick, by the mean of P URE DATA and O PEN S OUND C ONTROL (OSC) messages. A visual feedback tool using the P ROCESSING programming language is also presented in the most recent implementation. The aim of this research derives from a larger research project on physically-accurate sound field reproduction for simulators in engineering and industrial applications.
Download A toolkit for experimentation with signal interaction This paper will describe a toolkit for experimentation with signal interaction techniques, also commonly referred to as cross adaptive processing. The technique allows analyzed features of one audio signal to inform the processing of another. Earlier used mainly for mixing and post production purposes, we now want to use it creatively as an intervention in the musical communication between two performers. The idea stems from Stockhausen’s use of intermodulation in the 1960’s, and as such we might also call the updated technique interprocessing. Our interest in the technique comes as a natural extension to previous research on live processing as an instrumental and performative activity. The automatic control of signal processing routines is related to previous work on adaptive audio effects and automatic mixing. The focus for our investigation and experimentation with the current toolkit will be how this affects the musical communication between performers, and how it changes what they can and will play. The program code for the toolkit is available as a github repository1 under an open source license.
Download Improving the robustness of the iterative solver in state-space modelling of guitar distortion circuitry Iterative solvers are required for the discrete-time simulation of nonlinear behaviour in analogue distortion circuits. Unfortunately, these methods are often computationally too expensive for realtime simulation. Two methods are presented which attempt to reduce the expense of iterative solvers. This is achieved by applying information that is derived from the specific form of the nonlinearity. The approach is first explained through the modelling of an asymmetrical diode clipper, and further exemplified by application to the Dallas Rangemaster Treble Booster guitar pedal, which provides an initial perspective of the performance on systems with multiple nonlinearities.
Download Guaranteed-passive simulation of an electro-mechanical piano: a port-Hamiltonian approach This paper deals with the time-domain simulation of a simplified electro-mechanical piano. The physical model is composed of a hammer (nonlinear component), a cantilever beam (damped linear resonator) and a pickup (nonlinear transducer). In order to ensure stable simulations, a method is proposed, which preserves passivity, namely, the conservative and dissipative properties of the physical system. This issue is addressed in 3 steps. First, each physical component is described by a passive input-output system, which is recast in the port-Hamiltonian framework. In particular, a passive finite dimensional model of the Euler-Bernoulli beam is derived, based on a standard modal decomposition. Second, these components are connected, providing a nonlinear finite dimensional port-Hamiltonian system. Third, a numerical method is proposed, which preserves the power balance and passivity. Numerical results are presented and analyzed.
Download On the limits of real-time physical modelling synthesis with a modular environment One goal of physical modelling synthesis is the creation of new virtual instruments. Modular approaches, whereby a set of basic primitive elements can be connected to form a more complex instrument have a long history in audio synthesis. This paper examines such modular methods using finite difference schemes, within the constraints of real-time audio systems. Focusing on consumer hardware and the application of parallel programming techniques for CPU processors, useable combinations of 1D and 2D objects are demonstrated. These can form the basis for a modular synthesis environment that is implemented in a standard plug-in architecture such as an Audio Unit, and controllable via a MIDI keyboard. Optimisation techniques such as vectorization and multi-threading are examined in order to maximise the performance of these computationally demanding systems.
Download Two polarisation finite difference model of bowed strings with nonlinear contact and friction forces Recent bowed string sound synthesis has relied on physical modelling techniques; the achievable realism and flexibility of gestural control are appealing, and the heavier computational cost becomes less significant as technology improves. A bowed string is simulated in two polarisations by discretising the partial differential equations governing its behaviour, using the finite difference method; a globally energy balanced scheme is used, as a guarantee of numerical stability under highly nonlinear conditions. In one polarisation, a nonlinear contact model is used for the normal forces exerted by the dynamic bow hair, left hand fingers, and fingerboard. In the other polarisation, a force-velocity friction curve is used for the resulting tangential forces. The scheme update requires the solution of two nonlinear vector equations.Sound examples and video demonstrations are presented.