Download The wave digital reed: A passive formulation In this short paper, we address the numerical simulation of the single reed excitation mechanism. In particular, we discuss a formalism for approaching the lumped nonlinearity inherent in such a model using a circuit model and the application of wave digital filters (WDFs), which are of interest in that they allow simple stability verification, a property which is not generally guaranteed if one employs straightforward numerical methods. We present first a standard reed model, then its circuit representation, then finally the associated wave digital network. We then enter into some implementation issues, such as the solution of nonlinear algebraic equations, and the removal of delay-free loops, and present simulation results.
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 new estimation technique for determining the control parameters of a physical model of a trumpet A new estimation technique is proposed which computes the control parameters of a physical model of a trumpet in order to simulate a recording of a real instrument. First, the physical constraints of the instrument and the prior knowledge about how a player controls a trumpet are described. This is taken into account during the design of the data set and guarantees that these constraints are respected. Then, an estimation procedure minimizes two perceptual similarity criteria in function of the control parameters. The first criterium expresses the difference of the spectral envelopes and the second one the difference in fundamental frequency. An optimization technique is proposed that yields an optimal solution for the fundamental frequency, and a conditional suboptimal solution for the spectral envelope. A robust implementation of the technique was developed for which it is shown that the estimated parameters are unique and that the optimization does not suffer from local minima.
Download High frequency reconstruction for band-limited audio signals Current existing digital audio signals are always restricted by sampling rates and bandwidth fit for the various storages and communication bandwidth. Take for example the widely spread mp3 tracks encoded by the standard MPEG1 layer 3. The audio bandwidth in MP3 is restricted to 16 kHz due to the protocols constraints defined. This paper presents the method to reconstruct the lost high frequency components from the bandlimited signals. Both the subjective and objective measures have been conducted and shown the better quality. Especially, the important objective measurement by the perceptual evaluation of audio quality system, which is the recommendation system by ITU-R Task Group 10/4 has proven a significant quality improvement.
Download A simple, accurate wall loss filter for acoustic tubes This research presents a uniform approximation to the formulas of Benade and Keefe for the propagation constant of a cylindrical tube, valid for all tube radii and frequencies in the audio range. Based on this approximation, a simple expression is presented for a filter which closely matches the thermoviscous loss filter of a tube of specified length and radius at a given sampling rate. The form of this filter and the simplicity of coefficient calculation make it particularly suitable for real-time music applications where it may be desirable to have tube parameters such as length and radius vary during performance.
Download The voice of the dragon: A physical model of a rotating corrugated tube When an unsmooth flexible tube rotates, rich tones are produced. We propose a physical model that simulates this behavior. The tube is modeled as an open-ended organ pipe blown by an air stream pumped by a rotationally induced pressure which follows Bernoulli’s principle.
Download BLOCKCOMPILER – A research tool for physical modelling and DSP This paper describes an experimental research tool for block-based physical modeling and DSP computation. The goals of the development have been high abstraction level and flexibility in model specification without compromising computational efficiency in real-time simulation and application execution. To achieve both goals, the Lisp language is used for symbolic manipulation of computational block structures and C language for compilation of efficient executables. The primary motivation for this tool has been to enable flexible generation of physical models where twodirectional interaction between elements is needed. A particular feature of the system is support for mixed modeling by combining digital waveguides, finite difference schemes, wave digital filters, as well as traditional block-based DSP algorithms.
Download 10 criteria for evaluating physical modelling schemes for music creation The success recently encountered by physically-based modeling (or model-based approaches) for music should not mask the deep challenges that remain in this area. This article first proposes an overview of the various goals that researchers and musicians, respectively operating from scientific and end-user perspectives, may pursue. Among these goals, those recently proposed or particularly critical for the coming years of research are highlighted. The article then introduces ten criteria that summarize the main features an optimal physically-based modeling scheme or language should present. With respect to these, it proposes an evaluation of the major approaches to physically-based modeling. Key words: goals of the physically-based approach to sound synthesis and music creation, languages and schemes, enduser needs, perception, evaluation criteria, bibliographic overview.
Download M/S coding based on allocation entropy Main/Side (M/S) coding is a module deigned to reduce the channel irrelevancy and redundancies for multichannel coding in current audio standards. However, the success of this module relies on the careful design on four aspects: M/S decision, psychoacoustic model for the M/S channels, bits allocated between the M/S channels, and bit allocation in the M/S channels. This paper presents an efficient M/S method well designed from the four aspects. We conduct the experiments through the MP3 encoder to show the better quality and complexity than the Lame.