Acoustic modeling using the digital waveguide mesh

The digital waveguide mesh has been an active area of music acoustics research for over ten years. Although founded in 1-D digital waveguide modeling, the principles on which it is based are not new to researchers grounded in numerical simulation, FDTD methods, electromagnetic simulation, etc. This article has attempted to provide a considerable review of how the DWM has been applied to acoustic modeling and sound synthesis problems, including new 2-D object synthesis and an overview of recent research activities in articulatory vocal tract modeling, RIR synthesis, and reverberation simulation. The extensive, although not by any means exhaustive, list of references indicates that though the DWM may have parallels in other disciplines, it still offers something new in the field of acoustic simulation and sound synth

Designing and Composing for Interdependent Collaborative Performance with Physics-Based Virtual Instruments

Interdependent collaboration is a system of live musical performance in which performers can directly manipulate each other’s musical outcomes. While most collaborative musical systems implement electronic communication channels between players that allow for parameter mappings, remote transmissions of actions and intentions, or exchanges of musical fragments, they interrupt the energy continuum between gesture and sound, breaking our cognitive representation of gesture to sound dynamics. Physics-based virtual instruments allow for acoustically and physically plausible behaviors that are related to (and can be extended beyond) our experience of the physical world. They inherently maintain and respect a representation of the gesture to sound energy continuum. This research explores the design and implementation of custom physics-based virtual instruments for realtime interdependent collaborative performance. It leverages the inherently physically plausible behaviors of physics-based models to create dynamic, nuanced, and expressive interconnections between performers. Design considerations, criteria, and frameworks are distilled from the literature in order to develop three new physics-based virtual instruments and associated compositions intended for dissemination and live performance by the electronic music and instrumental music communities. Conceptual, technical, and artistic details and challenges are described, and reflections and evaluations by the composer-designer and performers are documented

Re-Sonification of Objects, Events, and Environments

abstract: Digital sound synthesis allows the creation of a great variety of sounds. Focusing on interesting or ecologically valid sounds for music, simulation, aesthetics, or other purposes limits the otherwise vast digital audio palette. Tools for creating such sounds vary from arbitrary methods of altering recordings to precise simulations of vibrating objects. In this work, methods of sound synthesis by re-sonification are considered. Re-sonification, herein, refers to the general process of analyzing, possibly transforming, and resynthesizing or reusing recorded sounds in meaningful ways, to convey information. Applied to soundscapes, re-sonification is presented as a means of conveying activity within an environment. Applied to the sounds of objects, this work examines modeling the perception of objects as well as their physical properties and the ability to simulate interactive events with such objects. To create soundscapes to re-sonify geographic environments, a method of automated soundscape design is presented. Using recorded sounds that are classified based on acoustic, social, semantic, and geographic information, this method produces stochastically generated soundscapes to re-sonify selected geographic areas. Drawing on prior knowledge, local sounds and those deemed similar comprise a locale's soundscape. In the context of re-sonifying events, this work examines processes for modeling and estimating the excitations of sounding objects. These include plucking, striking, rubbing, and any interaction that imparts energy into a system, affecting the resultant sound. A method of estimating a linear system's input, constrained to a signal-subspace, is presented and applied toward improving the estimation of percussive excitations for re-sonification. To work toward robust recording-based modeling and re-sonification of objects, new implementations of banded waveguide (BWG) models are proposed for object modeling and sound synthesis. Previous implementations of BWGs use arbitrary model parameters and may produce a range of simulations that do not match digital waveguide or modal models of the same design. Subject to linear excitations, some models proposed here behave identically to other equivalently designed physical models. Under nonlinear interactions, such as bowing, many of the proposed implementations exhibit improvements in the attack characteristics of synthesized sounds.Dissertation/ThesisPh.D. Electrical Engineering 201

Analysis and parametric synthesis of the piano sound

Tässä työssä tutkitaan pianon äänentuottomekanismia sekä akustisia ominaisuuksia. Tarkoituksena on luoda lähtökohdat pianon äänen parametriselle mallintamiselle. Lisäksi tutkitaan pianon äänen tärkeimpiä ominaisuuksia, kuten epäharmonisuutta, osaäänesten monimutkaista vaimenemisprosessia, kaikupohjan ja pedaalin ominaisuuksia sekä näiden tekijöiden vaikutuksia ääneen. Flyygelin ja pystypianon eroja tarkastellaan lyhyesti. Koska digitaalinen aaltojohtomallinnus tarjoaa parhaat lähtökohdat fysikaaliseen soitinmallinnukseen, tämä työ pohjautuu tähän tekniikkaan. Digitaalisen aaltojohtomallinnuksen pääpiirteet esitellään, kuten myös pianon kannalta olennaisimmat mallinnukseen liittyvät asiat. Lisäksi esitellään uusi tekniikka häviösuotimen suunnittelua varten, sekä annetaan muutama esimerkki käytännön suodinsuunnittelusta tällä tekniikalla. Tämän lisäksi tarkastellaan kaikupedaalin mallintamista sekä suoritetaan signaalianalyysi tehokkaan mallinnusalgoritmin löytämiseksi. Analysoitavat signaalit on äänitetty kahdessa äänityssessiossa vuoden 2005 aikana.In this thesis, an overview of the sound production mechanism of the piano is given. The acoustical properties of the instrument are studied in order to make a baseline for a physical and parametric model for the piano. In addition, the most important features of the piano sound, such as inharmonicity, the complicated decay process of the tones and the properties of the soundboard and the pedals, are investigated. The differences between the grand piano and the upright piano are considered in brief. As the digital waveguide technique is the most feasible physics-based sound synthesis technique at the moment, the synthesis procedure that is followed in this thesis is based on this technique. An overview of the main aspects of this synthesis scheme is given, and the most important modeling issues are taken into account from the piano sound synthesis point of view. A novel filter design technique for modeling the losses occurring in the piano sound is presented with some practical design examples. In addition, the modeling of the sustain pedal is discussed and signal analysis is performed in order to gather information for the synthetic sustain pedal algorithm. The analyzed signals are obtained from two recording sessions which were carried out in two parts during the year 2005

Caracterização vibroacústica e síntese sonora da viola caipira

Orientadores: José Maria Campos dos Santos, François Gautier, Frédéric AblitzerTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Le Mans UniversitéResumo: A viola caipira é um tipo de viola brasileira amplamente utilizada na música popular. Ela é composta de dez cordas metálicas dispostas em cinco pares, afinadas em uníssono ou oitava. Este trabalho de tese concentra-se na análise das especificidades dos sons musicais produzidos por este instrumento pouco estudado na literatura. A análise dos sons de viola caipira mostra a presença de vibrações simpáticas de cordas, o que resulta em um halo de som, constituindo uma característica perceptiva importante. Os movimentos de cordas dedilhadas são estudados usando uma câmera de alta velocidade, revelando a existência de choques entre cordas que levam a efeitos claramente audíveis. A análise modal das vibrações do corpo realizada por um vibrômetro à laser de varredura e um martelo de impacto automático permite identificar algumas diferenças em relação ao violão clássico. As mobilidades do cavalete também são medidas usando o método do fio quebrante, que é simples de usar e de baixo custo, uma vez que não requer o uso de um sensor de força. Combinadas com uma análise modal de alta resolução (método ESPRIT), tais medidas permitem determinar as formas modais nos pontos de acoplamento entre corda/corpo e assim caracterizar o instrumento. Uma modelagem física baseada em uma abordagem modal híbrida é realizada para fins de síntese sonora. Tal modelagem considera os movimentos das cordas em duas polarizações, os acoplamentos com o corpo e as colisões entre cordas. Este modelo é chamado de modelo híbrido porque combina uma abordagem analítica para descrever as vibrações de cordas e parâmetros experimentais que descrevem o corpo. Um conjunto de simulações no domínio do tempo revelam as principais características da viola caipiraAbstract: The viola caipira is a type of Brazilian guitar widely used in popular music. It consists of ten metallic strings arranged in five pairs, tuned in unison or octave. The thesis work focuses on the analysis of the specificities of musical sounds produced by this instrument, which has been little studied in the literature. The analysis of the motions of plucked strings using a high speed camera shows the existence of sympathetic vibrations, which results in a sound halo, constituting an important perceptive feature. These measurements also reveal the existence of shocks between strings, which lead to very clearly audible consequences. The modal analysis of the body vibrations, carried out by a scanning laser vibrometer and an automatic impact hammer reveals some differences and similarities with the classical guitar. Bridges mobilities are also measured using the wire-breaking method, which is simple to use and inexpensive since it does not require the use of a force sensor. Combined with a high-resolution modal analysis (ESPRIT method), these measurements enable to determine the modal shapes at the string/body coupling points and thus to characterize the instrument. A physical modelling, based on a modal approach, is carried out for sound synthesis purposes. It takes into account the strings motions with two orthogonal polarizations, the couplings with the body and the collisions between strings. This model is called a hybrid model because it combines an analytical approach to describe the vibrations of strings and experimental data describing the body. Simulations in the time domain reveal the main characteristics of the viola caipiraDoutoradoMecanica dos Sólidos e Projeto MecanicoDoutor em Engenharia Mecânica141214/2013-999999.010073/2014-00CNPQCAPE

Multisensory instrumental dynamics as an emergent paradigm for digital musical creation

The nature of human/instrument interaction is a long-standing area of study, drawing interest from fields as diverse as philosophy, cognitive sciences, anthropology, human–computer-interaction, and artistic creation. In particular, the case of the interaction between performer and musical instrument provides an enticing framework for studying the instrumental dynamics that allow for embodiment, skill acquisition and virtuosity with (electro-)acoustical instruments, and questioning how such notions may be transferred into the realm of digital music technologies and virtual instruments. This paper offers a study of concepts and technologies allowing for instrumental dynamics with Digital Musical Instruments, through an analysis of haptic-audio creation centred on (a) theoretical and conceptual frameworks, (b) technological components—namely physical modelling techniques for the design of virtual mechanical systems and force-feedback technologies allowing mechanical coupling with them, and (c) a corpus of artistic works based on this approach. Through this retrospective, we argue that artistic works created in this field over the last 20 years—and those yet to come—may be of significant importance to the haptics community as new objects that question physicality, tangibility, and creativity from a fresh and rather singular angle. Following which, we discuss the convergence of efforts in this field, challenges still ahead, and the possible emergence of a new transdisciplinary community focused on multisensory digital art forms

A digital waveguide-based approach for Clavinet modeling and synthesis

The Clavinet is an electromechanical musical instrument produced in the mid-twentieth century. As is the case for other vintage instruments, it is subject to aging and requires great effort to be maintained or restored. This paper reports analyses conducted on a Hohner Clavinet D6 and proposes a computational model to faithfully reproduce the Clavinet sound in real time, from tone generation to the emulation of the electronic components. The string excitation signal model is physically inspired and represents a cheap solution in terms of both computational resources and especially memory requirements (compared, e.g., to sample playback systems). Pickups and amplifier models have been implemented which enhance the natural character of the sound with respect to previous work. A model has been implemented on a real-time software platform, Pure Data, capable of a 10-voice polyphony with low latency on an embedded device. Finally, subjective listening tests conducted using the current model are compared to previous tests showing slightly improved results

Computationally efficient music synthesis : methods and sound design

Tässä diplomityössä esitetään musiikkisyntetisaattorin suunnittelua systeemille, jonka laskentateho ja muistikapasiteetti ovat rajoitettuja. Ensiksi kerrataan mahdollisia synteesitekniikoita sekä arvioidaan niiden käyttökelpoisuutta laskennallisesti tehokkaassa musiikkisynteesissä. Käytännössä käyttökelpoiset tekniikat ovat lisäävä ja lähde-suodinsynteesit, ja erikoistapauksissa taajuusmodulaatio-, aaltotaulukko- ja samplaussynteesit. Tämän jälkeen käyttökelpoisten tekniikoiden rakenteiden suunnittelua esitetään tarkemmin, sekä esitetään näiden rakenteiden ominaisuuksia ja suunnitteluongelmia. Suurin ongelma kohdataan digitaalisessa lähde-suodinsynteesissä, jossa klassisten aaltomuotojen, kuten saha-aallon käyttö lähdesignaalina on ongelmallista laskostumisen takia, joka johtuu aaltomuodossa olevista epäjatkuvuuksista. Olemassa olevia kaistarajoitettuja aaltomuotosynteesimenetelmiä kerrataan, ja polynomimuotoiseen kaistarajoitetuun askelfunktioon perustuvaa menetelmää esitellään tarkemmin antamalla suunnittelusääntöjä käyttökelpoisille polynomeille. Menetelmää testataan lisäksi kahdella kolmannen asteen polynomilla. Nämä polynomit vähentävät laskostumista korkeilla taajuuksilla enemmän verrattuna ensimmäisen asteen polynomiin, mutta pienillä taajuksilla ensimmäisen asteen polynomi tuottaa parempia tuloksia. Lisäksi kerrataan muita mahdollisia ääniefektialgoritmeja ja arvioidaan niiden käyttökelpoisuutta laskennallisesti tehokkaassa musiikkisynteesissä. Useasti äänisynteesisysteemin täytyy pystyä generoimaan musiikkia, jossa käytetään monia erilaisia ääniä, jotka ulottuvat oikeista akustisista soittimista elektronisiin soittimiin ja luonnon ääniin. Siksi tällainen systeemi tarvitsee huolellista äänten suunnittelua. Tässä diplomityössä esitetään suunnittelusääntöjä erilaisten äänien imitoimiseksi. Lisäksi esitellään synteesimenetelmien parametrien vaikutus äänivarianttien suunnitteluun.In this thesis, the design of a music synthesizer for systems suffering from limitations in computing power and memory capacity is presented. First, different possible synthesis techniques are reviewed and their applicability in computationally efficient music synthesis is discussed. In practice, the applicable techniques are limited to additive and source-filter synthesis, and, in special cases, to frequency modulation, wavetable and sampling synthesis. Next, the design of the structures of the applicable techniques are presented in detail, and properties and design issues of these structures are discussed. A major implementation problem is raised in digital source-filter synthesis, where the use of classic waveforms, such as sawtooth wave, as the source signal is challenging due to aliasing caused by waveform discontinuities. Methods for existing bandlimited waveform synthesis are reviewed, and a new approach using polynomial bandlimited step function is presented in detail with design rules for the applicable polynomials. The approach is also tested with two different third-order polynomials. They reduce aliasing more at high frequencies, but at low frequencies their performance is worse than with the first-order polynomial. In addition, some commonly used sound effect algorithms are reviewed with respect to their applicability in computationally efficient music synthesis. In many cases the sound synthesis system must be capable of producing music consisting of various different sounds ranging from real acoustic instruments to electronic instruments and sounds from nature. Therefore, the music synthesis system requires careful sound design. In this thesis, sound design rules for imitation of various sounds using the computationally efficient synthesis techniques are presented. In addition, the effects of the parameter variation for the design of sound variants are presented

Acoustic features of piano sounds

To date efforts of music transcription indicate the need for modelling the data signal in a more comprehensive manner in order to improve the transcription process of music performances. This research work is concerned with the investigation of two features associated with the reproduced sound of a piano; the inharmonicity factor of the piano strings and the double decay rate of the resulting sound. Firstly, a simple model of the inharmonicity is proposed and the factors that affect the modelled signal are identified, such as the magnitude of the inharmonicity, the number of harmonics, the time parameter, the phase characteristics and the harmonic amplitudes. A formation of a socalled “one-sided” effect appears in simulated signals, although this effect is obscured in real recordings potentially due to the non-uniformly varying amplitudes of the harmonic terms. This effect is also discussed through the use of the cepstrum by analysing real piano note recordings and synthesized signals. The cepstrum is further used to describe the effect of the coupled behaviour of two strings through digital waveguides. Secondly, the double decay rate effect is modelled through coupled oscillators and digital waveguides. A physical model of multiple strings is also presented as an extension to the simple model of coupled oscillators and various measurements on a real grand piano are carried out in order to investigate the coupling mechanism between the strings, the soundboard and the bridge. Finally, a model, with reduced dimensionality, is proposed to represent the signal model for single and multiple notes formulated around a Bayesian framework. The potential of such a model is illustrated with the transcription of simple examples of real monophonic and polyphonic piano recordings by implementing the Metropolis-Hastings algorithm and Gibbs sampler for multivariate parameter estimation