Download Physical Modeling for Spatial Sound Synthesis This contribution combines techniques for sound synthesis and spatial reproduction for a joint synthesis of the sound production and sound propagation properties of virtual string instruments. The generated sound field is reproduced on a massive multichannel loudspeaker system using wave field synthesis techniques. From physical descriptions of string vibrations and sound waves by partial differential equations follows an algorithmic procedure for synthesis-driven wave field reproduction. Its processing steps are derived by mathematical analysis and signal processing principles. Three different building blocks are addressed: The simulation of string vibrations, a model for the radiation pattern of the generated acoustical waves, and the determination of the driving signals for the multichannel loudspeaker array. The proposed method allows the spatial reproduction of synthetic spatial sound without the need for pre-recorded or pre-synthesized source tracks.
Download A Physical String Model with Adjustable Boundary Conditions The vibration of strings in musical instruments depends not only on their geometry and material but also on their fixing at the ends of the string. In physical terms it is described by impedance boundary conditions. This contribution presents a functional transformation model for a vibrating string which is coupled to an external boundary circuit. Delay-free loops in the synthesis algorithm are avoided by a state-space formulation. The value of the boundary impedance can be adjusted without altering the core synthesis algorithm.
Download Digital Sound Synthesis of Brass Instruments by Physical Modeling The Functional Transformation Method (FTM) is an established method for sound synthesis by physical modeling, which has proven its feasibility so far by the application to strings and membranes. Based on integral transformations, it provides a discrete solution for continuous physical problems given in form of initialboundary-value problems. This paper extends the range of applications of the FTM to brass instruments. A full continuous physical model of the instrument, consisting of an air column, a mouthpiece and the player’s lips is introduced and solved in the discrete domain. It is shown, that the FTM is a suitable method also for sound synthesis of brass instruments.
Download A Continuous Frequency Domain Description of Adjustable Boundary Conditions for Multidimensional Transfer Function Models Physical modeling of string vibrations strongly depends on the conditions at the system boundaries. The more complex the boundary conditions are the more complex is the process of physical modeling. Based on prior works, this contribution derives a general concept for the incorporation of complex boundary conditions into a transfer function model designed with simple boundary conditions. The concept is related to control theory and separates the treatment of the boundary conditions from the design of the string model.
Download Physical Modeling Using Recurrent Neural Networks with Fast Convolutional Layers Discrete-time modeling of acoustic, mechanical and electrical systems is a prominent topic in the musical signal processing literature. Such models are mostly derived by discretizing a mathematical model, given in terms of ordinary or partial differential equations, using established techniques. Recent work has applied the techniques of machine-learning to construct such models automatically from data for the case of systems which have lumped states described by scalar values, such as electrical circuits. In this work, we examine how similar techniques are able to construct models of systems which have spatially distributed rather than lumped states. We describe several novel recurrent neural network structures, and show how they can be thought of as an extension of modal techniques. As a proof of concept, we generate synthetic data for three physical systems and show that the proposed network structures can be trained with this data to reproduce the behavior of these systems.
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 Sound synthesis by physical modelling using the functional transformation method: Efficient implementations with polyphase-filterbanks The Functional Transformation Method (FTM) is a recently introduced method for sound synthesis by physical modeling. Based on integral transformations, it provides a parallel system description for any linear physical model, usually described by a set of partial differential equations. Such parallel descriptions can be directly implemented by a set of recursive systems in full rate. In this PSfrag replacem paper we present a new and very ef£cient method for this implementation which bene£ts from the spectral decomposition of the system. All recursive systems are working at a subsampled rate and are summed up by the application of a polyphase £lterbank. Performance measurements on a real time implementation show, that a ¤exible and ef£cient realization is achieved. Compared to the direct implementation it is over nine times faster at the cost of nine milliseconds of delay and even faster with more delay.
Download A String in a Room: Mixed-Dimensional Transfer Function Models for Sound Synthesis Physical accuracy of virtual acoustics receives increasing attention
due to renewed interest in virtual and augmented reality applications. So far, the modeling of vibrating objects as point sources
is a common simplification which neglects effects caused by their
spatial extent. In this contribution, we propose a technique for the
interconnection of a distributed source to a room model, based on
a modal representation of source and room. In particular, we derive a connection matrix that describes the coupling between the
modes of the source and the room modes in an analytical form.
Therefore, we consider the example of a string that is oscillating
in a room. Both, room and string rely on well established physical descriptions that are modeled in terms of transfer functions.
The derived connection of string and room defines the coupling
between the characteristic string and room modes. The proposed
structure is analyzed by numerical evaluations and sound examples
on the supplementary website.
Download Implementation of Arbitrary Linear Sound Synthesis Algorithms by Digital Wave Guide Structures The Digital Wave Guide (DWG) method is one of the most popular techniques for digital sound synthesis via physical modeling. Due to the inherent solution of the wave equation by the structure of the DWG method, it provides a highly efficient algorithm for typical physical modeling problems. In this paper it will be shown, that it is possible to use this efficient structure for any existing linear sound synthesis algorithm. By a consequent description of discrete implementations with State Space Structures (SSSs), suitable linear state space transformations can be used to achieve the typical DWG structure from any given system. The proposed approach is demonstrated with two case studies, where a modal solution achieved with the Functional Transformation Method (FTM) is transformed to a DWG implementation. In the first example the solution of the lossless wave equation is transformed to a DWG structure, yielding an arbitrary size fractional delay filter. In another example a more elaborated model with dispersion and damping terms is transformed, resulting in a DWG model with parameter morphing features.
Download Spatial Sound Synthesis for Circular Membranes Physical models of real or virtual instruments are usually only exploited for the generation of wave forms. However, models of twoand three-dimensional vibrating structures contain also information about the sound radiation into the free field. This contribution presents a model for a membrane from which the required driving functions for a multichannel loudspeaker array are derived. The resulting sound field reproduces not only the musical timbre of the sounding body but also its spatial radiation characteristics. It is suitable for real-time synthesis without pre-recorded or presynthesized source tracks.