19 research outputs found

    Simulation of distributed contact in string instruments: A modal expansion approach

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    Model-based analysis of noisy musical recordings with application to audio restoration

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    This thesis proposes digital signal processing algorithms for noise reduction and enhancement of audio signals. Approximately half of the work concerns signal modeling techniques for suppression of localized disturbances in audio signals, such as impulsive noise and low-frequency pulses. In this regard, novel algorithms and modifications to previous propositions are introduced with the aim of achieving a better balance between computational complexity and qualitative performance, in comparison with other schemes presented in the literature. The main contributions related to this set of articles are: an efficient algorithm for suppression of low-frequency pulses in audio signals; a scheme for impulsive noise detection that uses frequency-warped linear prediction; and two methods for reconstruction of audio signals within long gaps of missing samples. The remaining part of the work discusses applications of sound source modeling (SSM) techniques to audio restoration. It comprises application examples, such as a method for bandwidth extension of guitar tones, and discusses the challenge of model calibration based on noisy recorded sources. Regarding this matter, a frequency-selective spectral analysis technique called frequency-zooming ARMA (FZ-ARMA) modeling is proposed as an effective way to estimate the frequency and decay time of resonance modes associated with the partials of a given tone, despite the presence of corrupting noise in the observable signal.reviewe

    Analysis and resynthesis of polyphonic music

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    This thesis examines applications of Digital Signal Processing to the analysis, transformation, and resynthesis of musical audio. First I give an overview of the human perception of music. I then examine in detail the requirements for a system that can analyse, transcribe, process, and resynthesise monaural polyphonic music. I then describe and compare the possible hardware and software platforms. After this I describe a prototype hybrid system that attempts to carry out these tasks using a method based on additive synthesis. Next I present results from its application to a variety of musical examples, and critically assess its performance and limitations. I then address these issues in the design of a second system based on Gabor wavelets. I conclude by summarising the research and outlining suggestions for future developments

    Algorithms and architectures for the multirate additive synthesis of musical tones

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    In classical Additive Synthesis (AS), the output signal is the sum of a large number of independently controllable sinusoidal partials. The advantages of AS for music synthesis are well known as is the high computational cost. This thesis is concerned with the computational optimisation of AS by multirate DSP techniques. In note-based music synthesis, the expected bounds of the frequency trajectory of each partial in a finite lifecycle tone determine critical time-invariant partial-specific sample rates which are lower than the conventional rate (in excess of 40kHz) resulting in computational savings. Scheduling and interpolation (to suppress quantisation noise) for many sample rates is required, leading to the concept of Multirate Additive Synthesis (MAS) where these overheads are minimised by synthesis filterbanks which quantise the set of available sample rates. Alternative AS optimisations are also appraised. It is shown that a hierarchical interpretation of the QMF filterbank preserves AS generality and permits efficient context-specific adaptation of computation to required note dynamics. Practical QMF implementation and the modifications necessary for MAS are discussed. QMF transition widths can be logically excluded from the MAS paradigm, at a cost. Therefore a novel filterbank is evaluated where transition widths are physically excluded. Benchmarking of a hypothetical orchestral synthesis application provides a tentative quantitative analysis of the performance improvement of MAS over AS. The mapping of MAS into VLSI is opened by a review of sine computation techniques. Then the functional specification and high-level design of a conceptual MAS Coprocessor (MASC) is developed which functions with high autonomy in a loosely-coupled master- slave configuration with a Host CPU which executes filterbanks in software. Standard hardware optimisation techniques are used, such as pipelining, based upon the principle of an application-specific memory hierarchy which maximises MASC throughput

    Frequency-zooming ARMA modeling for analysis of noisy string instrument tones

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    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

    Analysis and parametric synthesis of the piano sound

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    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

    Multisensory instrumental dynamics as an emergent paradigm for digital musical creation

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    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
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