Digital Waveguide Mesh

This paper presents a digital waveguide woodwind instrument tonehole implementation which, in a single model, characterizes all states of the hole from open to closed. This efficient implementation produces results which agree well with previous acoustical analyses of the tonehole. A similar model is also presented for the register hole. A complete woodwind instrument model with many toneholes and register hole(s) is implemented in a cross-platform, C++ real-time computer programming environment. A new wind controller created to control the woodwind model is also briefly discussed.

The current interest in making and playing historical reproductions of recorders has led to an interest in the underlying acoustical principles. In this paper the basic acoustics connected with the recorder's sound production mechanism, bore and finger holes are outlined, and used to shed light on various aspects of the instrument's construction and playing technique.

This article summarises a lecture presented by the author at the second national Australian recorder festival, held in Melbourne in 1987. It provides an introduction to the basic and more complex acoustical principles that govern the sound of the recorder, and the implications for performers.

This paper is based on a lecture presented by the author at the first national Australian recorder festival held in Melbourne in 1984. Visual demonstrations of wave behaviour in springs are used to illustrate the invisible but audible aspects of sound production and modification in wind instruments, particularly the recorder.

This work deals with digital waveguide modeling of acoustic tubes, such as bores of musical woodwind instruments or the human vocal tract. The acoustic tube systems considered in this work are those consisting of a straight cylindrical or conical tube section or of a concatenation of several cylindrical or conical tube sections. Also, the junction of three tube sections is studied. Of special interest for our application are junctions where a side branch is connected to a cylindrical or conical tube since these are needed in the simulation of woodwind ...

The quena is a notched flute from South America. In southern and central Andes countless archeological specimens of notch flutes dating from prehispanic times have been found; they all share the same excitation technology but are different in several aspects such as the number of holes, the geometry of the notch and the size and shape of the tube. Today the quena is an instrument widely played in Latin America both in rural contexts, where they preserve a role and symbolism linked with the agricultural cycle, and in popular culture, where it adapted to tonal music. It is in the latter context that we propose to revise from an acoustic perspective the design of the bamboo quena, optimizing the position of the toneholes and modifying the geometry of the bore in order to obtain an instrument that is flexible and able to play tonal music as well as adapt to the chromatic needs of contemporary music. The analysis is based on a linear model of the acoustical propagation inside the instrum...

The quena is a notched flute from South America. In southern and central Andes countless archeological specimens of notch flutes dating from prehispanic times have been found; they all share the same excitation technology but are different in several aspects such as the number of holes, the geometry of the notch and the size and shape of the tube. Today the quena is an instrument widely played in Latin America both in rural contexts, where they preserve a role and symbolism linked with the agricultural cycle, and in popular culture, where it adapted to tonal music. It is in the latter context that we propose to revise from an acoustic perspective the design of the bamboo quena, optimizing the position of the toneholes and modifying the geometry of the bore in order to obtain an instrument that is flexible and able to play tonal music as well as adapt to the chromatic needs of contemporary music. The analysis is based on a linear model of the acoustical propagation inside the instrum...

The speed of sound in air increases with pressure, causing pressure peaks to travel faster than troughs, and leading to a sharpening of the propagating pressure waveform. Here, this nonlinear effect is explored, and its application to brass instrument synthesis and its use as an audio effect are described. Acoustic measurements on tubes and brass instruments are presented showing significant spectral enrichment, sometimes referred to as "brassiness." The effect may be implemented as an amplitudedependent delay, distributed across a cascade of incremental delays. A bidirectional waveguide, having a pressure-dependent delay, appropriate for musical instrument synthesis, is presented. A computationally efficient lumped-element processor is also presented. Example brass instrument recordings, originally played softly, are spectrally enriched or "brassified" to simulate a fortissimo playing level.

This paper addresses model-based analysis of string instrument sounds. In particular, it reviews the application of autoregressive (AR) modeling to sound analysis/synthesis purposes. Moreover, a frequency-zooming autoregressive moving average (FZ-ARMA) modeling scheme is described. The performance of the FZ-ARMA method on modeling the modal behavior of isolated groups of resonance frequencies is evaluated for both synthetic and real string instrument tones immersed in background noise. We demonstrate that the FZ-ARMA modeling is a robust tool to estimate the decay time and frequency of partials of noisy tones. Finally, we discuss the use of the method in synthesis of string instrument sounds.

Although they have been widely studied for years, some aspects of the behaviour of flute-like musical instruments remain poorly understood. The study of a physical model of the instrument has demonstrated its interest in the understanding of various phenomena, such as the hysteresis related to regime changes or the variations of the frequency with the blowing pressure. As it involves both nonlinear and delayed terms, an indepth study of the state of the art flute model requires specific numerical methods, which are often computationally expensive. The simplification of the model through its linearisation around a non-oscillating trivial solution is thus particularly interesting, due to the simplicity of the calculations. The information provided by such an analysis in terms of oscillation frequency or oscillation thresholds of the different periodic solutions has been highlighted in previous work. Surprisingly enough, the present study shows that this simple linear analysis provides information about the stability zones of the different periodic solutions (i.e. the different registers), and allows to predict, in some cases, the register resulting from a transient of the mouth pressure. Such information can be obtained without solving the nonlinear equations and without computing the steady-state oscillations of the model.

Direct numerical solutions of the compressible Navier-Stokes equations have been used to study various aspects of sound production in the recorder. A custom algorithm implemented on a parallel computer has enabled us to calculate tones and produce visualizations of the air flow near the labium in both two and three dimensions. In three dimensions, we have observed how the attack portion of the tone and the spectrum at long times depends on the relative alignment of the channel and labium. We also describe subtle differences in the process of vortex shedding in two as compared to three dimensions.

The aeroacoustics of a recorder are explored using a direct numerical simulation based on the Navier–Stokes equations in three dimensions. The qualitative behavior is studied using spatial maps of the air pressure and velocity to give a detailed picture of jet dynamics and vortex shedding near the labium. In certain cases, subtle but perhaps important differences in the motion of the air jet near the edge of the channel as compared to the channel center are observed. These differences may be important when analyzing experimental visualizations of jet motion. The quantitative behavior is studied through analysis of the spectrum of the sound pressure outside the instrument. The effect of chamfers and of changes in the position of the labium relative to the channel on the tonal properties are explored and found to be especially important in the attack portion of the tone. Changes in the spectrum as a result of variations in the blowing speed are also investigated as well as the behavio...

This paper presents a model-based sound synthesis algorithm for the Chinese plucked string instrument called the guqin. The instrument is fretless, which enables smooth pitch glides from one note to another. A version of the digital waveguide synthesis approach is used, where the string length is time-varying and its energy is scaled properly. A body model filter is placed in cascade with the string model. Flageolet tones are synthesized with the so-called ripple filter structure, which is an FIR comb filter in the delay line of a digital waveguide model. In addition, signal analysis of recorded guqin tones is presented. Friction noise produced by gliding the finger across the soundboard has a harmonic structure and is proportional to the gliding speed. For pressed tones, one end of a vibrating string is terminated either by the nail of the thumb or a fingertip. The tones terminated with a fingertip decay faster than those terminated with a thumb. Guqin tones are slightly inharmonic...

In this work, a technique is presented for estimating the reed pulse from the pressure signal recorded at the bell of a clarinet during performance. The reed pulse is a term given to the typically periodic sequence of bore input pressure pulses, a signal related to the volume flow through a vibrating reed by the characteristic impedance of the aperture to the bore. The problem is similar to extracting glottal pulse sequence from recorded speech; however, because the glottis and instrument reeds have very different masses and opening areas, the source-filter model used in speech processing is not applicable. Here, the reed instrument is modeled as a pressure-controlled valve coupled to a bi-directional waveguide, with the output pressure approximated as a linear time invariant transformation of the product of reed volume flow and the characteristic impedance of the bore. By noting that pressure waves will make two round trips from the mouthpiece to the bell and back for each reed pul...

Early harpsichords (before the adoption of well-tempered tuning systems) were sometimes built with "black" keys split front-to back. This javascript demo compares three different EDO keyboards : a Modern disposition 19-tone keyboard, a standard 12tone keyboard, and a third 19-tone keyboard with the ancient keyboard layout.

Holistic methods for acoustic design project are increasingly developed, combining the knowledge gained from physical acoustic researches, early stage noise mapping, architectural parameters and psychoacoustic. The aim of these methods is to combine subjective and objective parameters to achieve more performative outcomes to satisfy comfort needs. These methods require a methodological instrument to structure the design problem and to develop a heuristic mechanism acquiring broad rules to handle the specific solution. Today, digital tools handle large complex problems evolving from generative into intuitive tools such as the Artificial Intelligence (AI). AI, through the deep learning, discovers intricate structure in large data sets, by using the backpropagation algorithm, to indicate machine’s way to change its internal parameters thus helping to develop unpredictable innovative solutions. The paper intends to develop a theoretical background based on bibliographic survey of AI in ...

A Greek language text reading program has been constructed which generates control files for the SPASM/Singer physical model of the human singing voice. A simple rule system for Modem Greek determines pronunciation. The Greek text is processed in stream fashion, yielding a text file which controls the Singer instrument. Note names, frequencies, or functions specifying pitch are imbedded directly into the text using o brackets. Note durations are extended with dashes. Tuning systems based on a large number of Greek microtonal modes have been specified. A number of commonly used Greek vocal ornaments have been specified as C functions, and can be passed to the Singer instrument using {} braces. The system allows for easy creation of new ornaments, figures, words, and tuning systems.

A haptic musical instrument is an electronic musical instrument that provides the musician not only with audio feedback but also with force feedback. By programming feedback controllers to emulate the laws of physics, many haptic musical instruments have been previously designed that mimic real acoustic musical instruments. The controller programs have been implemented using finite difference and (approximate) hybrid digital waveguide models. We present a novel method for constructing haptic musical instruments in which a haptic device is directly interfaced with a conventional digital waveguide model by way of a junction element, improving the quality of the musician’s interaction with the virtual instrument. We introduce both the explicit digital waveguide control junction and the implicit digital waveguide control junction.

Two "one-filter" scattering junctions are derived which provide very accurate models of woodwind toneholes in the context of a digital waveguide model. Because toneholes in the clarinet possess only one resonance and/or anti-resonance within the audio band, a second-order digital filter suffices.

Abstract: In this paper we briefly overview the digital waveguide mesh method. It is a wave-based technique for room acoustic prediction operating in the time domain. The original technique suffers from direction dependent dispersion. In this paper we discuss couple of techniques that have been applied to overcome this problem. Firstly, the interpolated mesh structure, and secondly the frequency warping technique are presented. As a case study we present simulation results and visualizations obtained with two simple room geometries. In ...

This paper presents the concept of "scientific concerts" developed at Le Mans University by two acoustics teachers-researchers and professional musicians, with the collaboration of three professional musicians. This project was born in 2009 and aims to introduce the basic concepts of acoustics by mixing science and arts. The originality and core principle of a scientific concert is to combine projected animations and spoken explanations with real-time experiments and demonstrations that are being given and played by both physicists and musicians. Learning is also eased by alternating musical themes and scientific content. Two different shows have been developed and given either in high schools, in popular science events or in concerts halls welcoming teenagers or general audience. The first show deals with the three main characteristics of a sound (intensity, pitch, timbre), while the second introduces the physics of musical instruments using the principles of elemental resonators like ducts and strings. The presentation will describe the science-to-music back-and-forth process that has been followed so as to achieve this project, including examples of experiments and auditory demonstrations. A quantitative and qualitative assessment of the concerts given in France and Canada will be finally provided.

This paper describes recent investigations on sound production mechanism of a sho, the Japanese traditional wind instruments. Shos, as well as shengs in China and khaens in Laos and Thailand, are categorized as free reed instruments with pipe resonators. An experiment was made to measure the reed motion and sound pressures using the artificially blown sho. According to the experiments, it was concluded that the sho reeds acted as ”outward-strikng valves” in contrast with those of the clarinet. Then, a physical model of the sho was constructed based on mathematical formula, and a timedomain simulation was done. The simulation results were compared with the experimental results, and the agreement was acceptably good for basic characteristics. Further modification to improve sound quality was also done. An application of the model to sound synthesis is briefly introduced.

This paper proposes a synthesis framework for sound hybridization that creates sho-like sounds with articulations that are the same as that of a given input signal. This approach has three components: acoustic feature extraction, physical parameter estimation, and waveform synthesis. During acoustic feature extraction, the amplitude and fundamental frequency of the input signal are extracted, and in the parameter estimation stage these values are converted to control parameters for the physical model. Then, using these control parameters, a sound waveform is calculated during the synthesis stage. Based on the proposed method, a mapping function between acoustical parameters and physical parameters was determined using recorded sho sounds. Then, sounds with various articulations were synthesized using several kinds of instrumental tones. As a result, sounds with natural frequency and amplitude variations such as vibrato and portamento were created. The proposed method was used in music composition and proved to be effective.

In musical instruments, the geometric design and material features of the instrument are the most important factors that determine the sound characteristics of the instrument. Traditional replication and experiment-based handcrafting methods are predominant in the production of Turkish Folk Music wind instruments. The instrument manufacturing and standardization approaches, which include the relevant rules of physics and engineering practices, are limited purely to prototype studies for scientific research purposes. It is almost impossible to find studies on Turkish Folk Music wind instrument design and production involving computer aided design and engineering applications. In this study, an example Turkish woodwind instrument, the Turkish Treble Recorder (dilli kaval) is considered, and the air flow behaviour and acoustic (sound) power magnitudes that occur at different air flow rates are simulated in a computer environment using a Computational Fluid Dynamics (CFD) simulation technique. In the study, numerical and visual outputs related to air behaviour at different air flow rates that may be used in the instrument manufacturing phases were obtained. Acoustic power level was also measured experimentally. Simulation outputs (the acoustic power level) were compared to experimental results in order to validate the simulation results. The comparison revealed that the highest relative difference was calculated as 13.32(%). This value indicated that the simulation results were reasonably consistent with the results of the experimental measurement. Additionally, this study was constructed as a case study that may provide reference for future research studies in this field.

This report presents a model-based sound synthesis algorithm for the Chinese plucked string instrument called the guqin. The instrument is fretless, which enables smooth pitch glides from a note to another. A version of the digital waveguide synthesis approach is used, where the string length is time-varying and its energy is scaled properly. A body model filter is placed in cascade with the string model. Flageolet tones are synthesized with the so called ripple filter structure, which is an FIR comb filter in the delay line of a digital waveguide model. In addition, signal analysis of recorded guqin tones is presented. Friction noise produced by gliding the finger across the soundboard has a harmonic structure and is proportional to the gliding speed. For pressed tones, one end of a vibrating string is terminated either by the nail of the thumb or a fingertip. The tones terminated with a fingertip decay faster than those terminated with a thumb. Guqin tones are slightly inharmonic and they exhibit phantom partials. The synthesis model takes into account these characteristic features of the instrument and is able to reproduce them. The synthesis model will be used for rule based synthesis of guqin music.

Digital waveguide modeling of musical instruments is one of the most popular sound synthesis techniques at present. This methodology has been mainly developed by Smith [1]. Digital waveguide modeling is well suited to synthesis of wind and string instruments, although the same principles have recently been applied to the piano and percussion instruments as well.

Finite amplitude standing waves in acoustic resonators are simulated. The fluid is initially at rest 15 and excited by a harmonic motion of the entire resonator. The unsteady compressible Navier-16 Stokes equations and the state equation for an ideal gas are employed. This study extends the 17 traditional pressure based finite volume SIMPLEC scheme for solving the equations without any 18 predefined standing waves. The pressure waveforms are computed in three different closed 19 resonators and two opened resonators. The studied shapes of resonators include cylinder, cone 20 and exponential horn. The numerical results obtained from the proposed finite volume method in 21 the study are in agreement with those obtained with the Galerkin method and the finite difference 22 method. We also investigate the velocity waveforms in the three different kinds of resonators, 23 and finds that the sharp velocity spikes appear at the ends of the resonator when the pressure has 24 shock-like waveform. The velocity in the closed conical resonator displays smooth harmonic 25 waveform. Finally, the pressure waveforms in opened resonators are simulated and analyzed. 26 The results show that the decrease in the ratio of the maximum to the minimum pressure at the 27 small end of the exponential resonator is less than that of cylindrical resonators when the flow 28 velocity at the opened end (relative to the resonator) is same.

This paper reviews recent developments in physics-based synthesis of piano. The paper considers the main components of the instrument, that is, the hammer, the string, and the soundboard. Modeling techniques are discussed for each of these elements, to-gether with implementation strategies. Attention is focused on numerical issues, and each implementation technique is described in light of its efficiency and accuracy properties. As the structured audio coding approach is gaining popularity, the authors argue that the physical modeling approach will have relevant applications in the field of multimedia communication.

Field-Programmable Gate Array (FPGA) offers advantages for many applications, particularly where missions are complex and time performance is critical. For small-production digital acoustic synthesizers, FPGA can achieve the abovementioned tighter system requirements with low total system costs on single chip. In this manuscript, a real-time acoustic synthesizer is implemented using Fourier series algorithm on Altera's Cyclone II FPGA chip. This work emphasizes systematic designs and parallel computations. The proposed system includes a flexible processor and a parallel parameterized acoustic module. On one hand, the Nios II embedded processor, which is relatively low-speed component, is used to generate commands and configure high-speed acoustic module parameters. On the other hand, acoustic module which should require high-speed components contains 4 parallel architectures to gain high-speed simultaneous calculus of 4 independent digital timbres. Every timbre is equivalent to 16 parallel high-precision harmonic channels with 0.3 % frequency error. Experimental results corroborate the fact that a single FPGA chip can achieve complex missions and attain real-time performances.

Abstract. The CyberWhistle is an integrated approach to a new electronic instrument, with emphasis given to aesthetic and practical considerations. It consists of a penny whistle1 fitted with sensors and electronics connected by cable to a desktop computer, a Silicon Graphics Indy. In contrast to many windcontrollers, the continuous position of the fingers is sensed. Audio is produced on multiple channels using various software synthesis methods, including waveguide modeling. The design of software and hardware have proceeded in ...

This paper reviews recent developments in physics-based synthesis of piano. The paper considers the main components of the instrument, that is, the hammer, the string, and the soundboard. Modeling techniques are discussed for each of these elements, together with implementation strategies. Attention is focused on numerical issues, and each implementation technique is described inlightofitsefficiency and accuracy properties. As the structured audio coding approach is gaining popularity, the authors argue that the physical modeling approach will have relevant applications in the field of multimedia communication.

This paper presents a novel spatial auditory display that combines a virtual environment based on a Digital Waveguide Mesh (DWM) model of a small tubular shape with a binaural rendering system with personalized headrelated transfer functions (HRTFs) allowing interactive selection of absolute 3D spatial cues of direction as well as egocentric distance. The tube metaphor in particular minimizes loudness changes with distance, providing mainly direct-to-reverberant and spectral cues. The proposed display was assessed through a target-reaching task where participants explore a 2D virtual map with a pen tablet and hit a sound source (the target) using auditory information only; subjective time to hit and traveled distance were analyzed for three experiments. The first one aimed at assessing the proposed HRTF selection method for personalization and dimensionality of the reaching task, with particular attention to elevation perception; we showed that most subjects performed better when they had to reach a vertically unbounded (2D) rather then an elevated (3D) target. The second experiment analyzed interaction between the tube metaphor and HRTF showing a dominant effect of DWM model over binaural rendering. In the last experiment, participants using absolute distance cues from the tube model performed comparably well to when they could rely on more robust, although relative, intensity cues. These results suggest that participants made proficient use of both binaural and reverberation cues during the task, displayed as part of a coherent 3D sound model, in spite of the known complexity of use of both such B Michele Geronazzo