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  • 1. Alexandre, Enrique
    et al.
    Gil-Pita, Roberto
    Raspaud, Martin
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    On the Evaluation of the Performance of Music Instrument Classification Systems2008In: 10th Meeting of the AES Portugal, 2008Conference paper (Other academic)
  • 2. Arcella, A
    et al.
    Cavaliere, S
    Università di Napoli.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Recognition of sounds from musical instruments: a critical review and experiments2004In: Proc. of the IV Conference on Understanding and Creating Music (UCM), 2004Conference paper (Other academic)
  • 3.
    Baravdish, George
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Svensson, Olof
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Sofya, Faten
    Mosul University, Mosul, Iraq.
    PDE-SVD Based Audio Denoising2012In: Proceedings of the 5th International Symposium on Communications Control and Signal Processing (ISCCSP), 2012, Piscataway, NJ, USA: IEEE , 2012, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this paper we present a new method for denoising audio signals. The method is based on the Singular Value Decomposition (SVD) of the frame matrix representing the signal inthe Overlap Add decomposition. Denoising is performed by modifying both the singular values, using a tapering model, and the singular vectors of the representation, using a nonlinear PDE method. The performance of the method is evaluated and compared with denoising obtained by filtering.

  • 4.
    Bock, Alexander
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lang, Norbert
    St. Barbara Hospital, Hamm, Germany.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lehrke, Ralph
    St. Barbara Hospital, Hamm, Germany.
    Ropinski, Timo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Guiding Deep Brain Stimulation Interventions by Fusing Multimodal Uncertainty Regions2013Conference paper (Other academic)
    Abstract [en]

    Deep Brain Stimulation (DBS) is a surgical intervention that is known to reduce or eliminate the symptoms of common movement disorders, such as Parkinson.s disease, dystonia, or tremor. During the intervention the surgeon places electrodes inside of the patient.s brain to stimulate speci.c regions. Since these regions span only a couple of millimeters, and electrode misplacement has severe consequences, reliable and accurate navigation is of great importance. Usually the surgeon relies on fused CT and MRI data sets, as well as direct feedback from the patient. More recently Microelectrode Recordings (MER), which support navigation by measuring the electric .eld of the patient.s brain, are also used. We propose a visualization system that fuses the different modalities: imaging data, MER and patient checks, as well as the related uncertainties, in an intuitive way to present placement-related information in a consistent view with the goal of supporting the surgeon in the .nal placement of the stimulating electrode. We will describe the design considerations for our system, the technical realization, present the outcome of the proposed system, and provide an evaluation.

  • 5.
    Bock, Alexander
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lang, Norbert
    St. Barbara Hospital, Hamm, Germany.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lehrke, Ralph
    St. Barbara Hospital, Hamm, Germany.
    Ropinski, Timo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Supporting Deep Brain Stimulation Interventions by Fusing Microelectrode Recordings with Imaging Data2012Conference paper (Refereed)
  • 6.
    Cavaliere, Sergio
    et al.
    University of Naples.
    Evangelista, Gianpaolo
    University of Naples.
    Romano, Luigi
    University of Naples.
    Un nuovo metodo di analisi e stima dei parametri per la sintesi di suoni mediante algoritmo Karplus-Strong1996In: Proc. of XXIV Convegno AIA (Associazione Italiana di Acustica), 1996, p. 197-200Conference paper (Other academic)
  • 7.
    Eckerholm, Fredrik
    et al.
    Audio Sony-Ericsson.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    The PluckSynth touch string2008In: Proc. of Digital Audio Effects Conf. (DAFx `08), Helsinki, Finland: DAFx , 2008, p. 213-220Conference paper (Refereed)
    Abstract [en]

    In this paper the problem of the synthesis of plucked strings by means of physically inspired models is reconsidered in the context of the player-s interaction with the virtual instrument. While solutions for the synthesis of guitar tones have been proposed, which are excellent from the acoustic point of view, the problem of the control of the physical parameters directly by the player has not received sufficient attention. In this paper we revive a simple model previously presented by Cuzzucoli and Lombardo for the player-s touch. We show that the model is affected by an inconsistency that can be removed by introducing the finger/pick perturbation in a balanced form on the digital waveguide. The results, together with a more comprehensive model of the guitar have been implemented in a VST plugin, which is the starting point for further research.

  • 8.
    Evangelista, Gianpaolo
    Istituto Nazionale di Fisica Nucleare, Sez. Napoli.
    Data Analysis Methods for Non-Gaussian, Nonstationary and Nonlinear Features and their Application to VIRGO2003In: Classical and Quantum Gravity, ISSN 0264-9381, Vol. 20, no 17, p. S915-S924Article in journal (Refereed)
    Abstract [en]

    The commissioning of the VIRGO central interferometer occasioned the implementation and tests of various algorithms for the characterization of the non-Gaussianity, non-stationarity and non-linearity of the dark fringe data. This library of prototypes will serve as groundwork for the near commissioning of VIRGO (full scale). We make a summary of the activities on that subject including the description of the selected algorithms and some results obtained with the data of the engineering runs.

  • 9.
    Evangelista, Gianpaolo
    Federal Institute of Technology, Lausanne, Switzerland.
    Dyadic Warped Wavelets2001In: Advances in Imaging and Electron Physics, ISSN 1076-5670, Vol. 117, p. 73-171Article in journal (Refereed)
  • 10.
    Evangelista, Gianpaolo
    Swiss Federal Institute of Technology, Audio-Visual Communication Laboratory, Lausanne,.
    Flexible Wavelets for Music Signal Processing2001In: Journal of New Music Research, ISSN 0929-8215, Vol. 30, no 1, p. 13-22Article in journal (Refereed)
    Abstract [en]

    Musical signals require sophisticated time-frequency techniques for their representation. In the ideal case, each element of the representation is able to capture a distinct feature of the signal and can be attached either a perceptual or an objective meaning. Wavelet transforms constitute a remarkable advance in this field and have several advantages over Gabor expansions or short-time Fourier methods. However, application of conventional wavelet bases on musical signals produces disappointing results for at least two reasons: (1) the frequency resolution of dyadic wavelets is one-octave, too poor for any meaningful acoustic decomposition and (2) pseudoperiodicity or pitch information of voiced sounds is not exploited. Fortunately, the definition of wavelet transform can be extended in several directions, allowing for the design of bases with arbitrary frequency resolution and for adaptation to time-varying pitch characteristic in signals with harmonic or even inharmonic structure of the frequency spectrum. In this paper we discuss refined wavelet methods that are applicable to musical signal analysis and synthesis. Flexible wavelet transforms are obtained by means of frequency warping techniques.

  • 11.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Fractal Modulation Effects2013In: Proc. of Digital Audio Effects Conference (DAFx `06), Montreal, Canada: DAFx , 2013, p. 101-106Conference paper (Refereed)
    Abstract [en]

    Fractal modulation is obtained by forming a power weighted superposition of scaled and modulated versions of the signal. The resulting signal is self-similar with fractal characteristics. In this paper we explore fractal modulation as a powerful method to generate rich signals, useful both for the synthesis of complex sounds, like the sounds from natural events or ecological sounds, or as control functions of audio effects. The wavelet transform can be used as an efficient tool in order to generate a subset of fractal modulated signals that are power homogeneous. Any signal used as a seed for fractal modulation is transformed into a multiscale sound by means of a tree-structured multirate filter bank. Moreover, by superimposing a structured modulation scheme one can generate pseudo-periodic sounds whose partials have fractal behavior.

  • 12.
    Evangelista, Gianpaolo
    University of Napoli .
    Last Stage Control and Mechanical Transfer Function Measurement of the VIRGO Suspensions2002In: Review of Scientific Instruments, ISSN 0034-6748, Vol. 73, p. 2143-2149Article in journal (Refereed)
    Abstract [en]

    The automatic control of the suspended mirrors is a major task in operating an interferometric gravitational wave antenna. To reach the extreme sensitivity required for this kind of detector, an accurate alignment and a stable locking of the interferometer on its working point are crucial. The solution of this problem is particularly complex in the case of a multistage pendulum, such as the suspension system for seismic isolation adopted in VIRGO. A precise knowledge of the suspension mechanical transfer functions (TFs) for different forces applied in the control servo-loops represents essential information to reach the goal. In this article, we describe the apparatus we developed to measure the VIRGO suspension TF and we report the results thus obtained on full-scale suspensions at the VIRGO site. Preliminary results for the implemented control system of the last suspension stage are also presented

  • 13.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Modified phase vocoder scheme for dynamic frequency warping2008In: 3rd International Symposium on Communications, Control and Signal Processing, 2008. ISCCSP 2008., Piscataway, NJ, USA: IEEE , 2008, p. 1291-1296Conference paper (Refereed)
    Abstract [en]

    Frequency warping is a desirable building block for sound effects and synthesis. Physical model driven pitch shifting of inharmonic sounds and the transformation of harmonic into inharmonic sounds are the main features of frequency warping effects. However, frequency warping sound signals is a non-causal and computationally expensive operation. In recent work [1] we showed that multirate filter bank s derived from a modified phase vocoder structure are suitable for the real-time approximate computation of frequency warping. The approximation is proven to be very accurate from both numerical and perceptual points of view. In this paper we extend the principles of the original design to implement time-varying frequency warping methods. The proposed algorithm is suitable for inclusion in the synthesis of systems with dynamic stiffness and for the production of captivating audio effects.

  • 14.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Physical Model of the Slide Guitar: An Approach Based on Contact Forces2012In: Proceedings of Audio Engineering Society Convention 132, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper we approach the synthesis of the slide guitar, which is a particular play mode of the guitar where continuous tuning of the tones is achieved by sliding a metal orglass piece, the bottleneck, along thestrings on the guitar neck side. The bottleneck constitues a unilateral constraint for the string vibration.Dynamics is subject to friction, scraping, textured displacement and collisions. The presented model is physically inspired and is based on a dynamic model of friction, together with a geometrical model of the textured displacements and a model for collisions of the string with the bottlenck. These models are suitablefor implementation in a digital waveguide computational scheme for the 3D vibration of the string, where continuous pitch bending is achieved by allpass filters to approximate fractional delays, friction is captured by nonlinear state-space systems in the slide junction and textured displacements by signal injection at avariable point in the waveguide.

  • 15.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Physical Model of the String-Fret Interaction2011In: Proc. of Digital Audio Effect Conf., 2011, p. 345-351.Conference paper (Refereed)
    Abstract [en]

    In this paper, a model for the interaction of the strings with the frets in a guitar or other fretted string instruments is introduced. In the two-polarization representation of the string oscillations it is observed that the string interacts with the fret in different ways. While the vertical oscillation is governed by perfect or imperfect clamping of the string on the fret, the horizontal oscillation is subject to friction of the string over the surface of the fret. The proposed model allows, in particular, for the accurate evaluation of the elongation of the string in the two modes, which gives rise to audible dynamic detuning. The realization of this model into a structurally passive system for use in digital waveguide synthesis is detailed. By changing the friction parameters, the model can be employed in fretless instruments too, where the string directly interacts with the neck surface.

  • 16.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Physically inspired playable models of guitar, a tutorial2010In: Proc. 4th International Symposium on Digital Communications, Control and Signal Processing (ISCCSP), 2010, p. 1-4Conference paper (Refereed)
  • 17.
    Evangelista, Gianpaolo
    Swiss Federal Institute of Technology, Lausanne.
    Real-Time Time-Varying Frequency Warping via Short-Time Laguerre Transform2000In: Proc. of Digital Audio Effects Conference (DAFx ‘00), 2000, p. 7-12Conference paper (Other academic)
    Abstract [en]

    n/a

  • 18.
    Evangelista, Gianpaolo
    Università di Napoli.
    Status and Noise Limit of the VIRGO Antenna Laser Interferometer Space Antenna1998In: Proc. 2-nd Internat. LISA Symp. on the Detection and Observation of Gravitational Waves in Space, 1998, Vol. 456, p. 222-225Conference paper (Other academic)
  • 19.
    Evangelista, Gianpaolo
    University of Napoli.
    The Gravitational Wave Detector VIRGO2002In: Proc. of 26th Advanced ICFA Beam Dynamics Workshopï¿œon Nanometre-Size Colliding Beams, 2002Conference paper (Other academic)
  • 20.
    Evangelista, Gianpaolo
    University of Napoli.
    The Present Status of the VIRGO Central Interferometer2002In: Classical and Quantum Gravity, ISSN 0264-9381, Vol. 19, no 7, p. 1421-1428Article in journal (Refereed)
    Abstract [en]

    The VIRGO Central Interferometer (CITF) is a short suspended interferometer operated with the central area elements of the VIRGO detector. The main motivation behind the CITF is to allow the integration and debugging of a large part of the subsystems of VIRGO while the construction of the long arms of the antenna is being completed. This will permit a faster commissioning of the full-size antenna. In fact, almost all the main components of the CITF, with the exception of the large mirrors and a few other details, are the same as those to be used for the full-size detector. In this paper the present status of the VIRGO CITF is reported.

  • 21.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Time and Frequency Warping of Musical Signals2011In: DAFX: digital audio effects / [ed] Udo Zölzer, John Wiley & Sons, 2011, 2, p. 447-471Chapter in book (Other academic)
  • 22.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Cavaliere, Sergio
    Univ. of Naples, Italy.
    Event Synchronous Thumbnails: Experiments2005In: Proc. of Sound and Music Computing Conf. (SMCᅵ05), 2005Conference paper (Other academic)
  • 23.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Cavaliere, Sergio
    Dept. Physical Sciences Federico II of Naples, Italy.
    Real-Time and Efficient Algorithms for Frequency Warping Based on Local Approximations of Warping Operators2007In: Proc. of Digital Audio Effects Conf. (DAFx `07), France: DAFx , 2007, p. 269-276Conference paper (Refereed)
    Abstract [en]

    Frequency warping is a modifier that acts on sound signals by remapping the frequency axis. Thus, the spectral content of the original sound is displaced to other frequencies. At the same time, the phase relationship among the signal components is altered, nonlinearly with respect to frequency. While this effect is interesting and has several applications, including in the synthesis by physical models, its use has been so far limited by the lack of an accurate and flexible real-time algorithm. In this paper we present methods for frequency warping that are based on local approximations of the warping operators and allow for real-time implementation. Filter bank structures are derived that allow for efficient realization of the approximate technique. An analysis of the error is also presented, which shows that both numerical and perceptual errors are within acceptable limits. Furthermore, the approximate implementation allows for a larger variety of warping maps than that achieved by the classical (non-causal) first-order allpass cascade implementation.

  • 24.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Cavaliere, Sergio
    Univ. of Naples, Italy.
    Tontodonato, Valentino
    Event Synchronous Thumbnails: Statistical Properties2005In: Proc. of the V Conference on Understanding and Creating Music (UCM), 2005Conference paper (Other academic)
  • 25.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Dörfler, Monika
    University of Vienna, Austria.
    Matusiak, Ewa
    University of Vienna, Austria.
    Phase vocoders with arbitrary frequency band selection2012In: Proceedings of the 9th Sound and Music Computing Conference, Copenhagen, Denmark, 2012, p. 442-449Conference paper (Other academic)
  • 26.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Eckerholm, Fredrik
    Sony Ericsson Mobile Communication.
    Player-Instrument Interaction Models for Digital Waveguide Synthesis of Guitar: Touch and Collisions2010In: IEEE TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING, ISSN 1558-7916, Vol. 18, no 4, p. 822-832Article in journal (Refereed)
    Abstract [en]

    Physically inspired sound synthesis techniques have been devised for several instruments including guitar. Less well studied are methods to model the interactions of the player with strings and of the strings with other mechanical parts of the instrument. In this paper, we present methods based on simple scattering junctions to be inserted at various points along a digital waveguide simulating transversal wave propagation along a string. These junctions, which are derived using a balanced perturbation method for displacement wave variables, connect the waveguide with the external stimuli provided by the player or with objects that are part of the instrument. A model for plucking is revisited and improved. New nonlinear structures for the accurate model of collisions are developed. The proposed junctions achieve realistic synthesis of the interaction of the plucking finger or pick with the string, of the interaction of the fingers on the neck-side hand with strings, such as in the production of harmonics, and of the strings themselves with frets or fingerboard in a fretless instrument.

  • 27.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Marchand, Sylvain
    University of Bordeaux, France.
    Plumbley, Mark D.
    Queen Mary University of London, UK.
    Vincent, Emmanuel
    INRIA-Rennes, France .
    Sound Source Separation2011In: DAFX: digital audio effects / [ed] Udo Zölzer, John Wiley & Sons, 2011, 2, p. 551-588Chapter in book (Other academic)
  • 28.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Polotti, Pietro
    VIPS University of Verona, Italy.
    Fractal Additive Synthesis: a Deterministic/Stochastic Model for Sound Synthesis by Analysis2007In: IEEE signal processing magazine (Print), ISSN 1053-5888, E-ISSN 1558-0792, Vol. 24, no 2, p. 105-115Article in journal (Refereed)
  • 29.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Raspaud, Martin
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Simplified Guitar Bridge Model for the Displacement Wave Representation in Digital Waveguides2009In: Proceedings of the 12th International Conference on Digital Audio Effects, DAFx 2009, 2009, p. 484-491Conference paper (Other academic)
  • 30.
    Germain, François
    et al.
    Ecole Polytechnique.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Synthesis of Guitar by Digital Waveguides: Modeling the Plectrum in the Physical Interaction of the Player with the Instrument2009In: Proc. of the IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA-09), 2009, p. 25-28Conference paper (Other academic)
    Abstract [en]

    In this paper, we provide a model of the plectrum, or guitar pick, for use in physically inspired sound synthesis. The model draws from the mechanics of beams. The profile of the plectrum is computed in real time based on its interaction with the string, which depends on the movement impressed by the player and the equilibrium of dynamical forces. A condition for the release of the string is derived, which allows to drive the digital waveguide simulating the string to the proper state at release time. The acoustic results are excellent, as verified in the sound examples provided.

  • 31.
    Huang, Lixia
    et al.
    Taiyuan University of Technology, China.
    Zhang, Xueying
    Taiyuan University of Technology, China.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Speaker independent recognition on OLLO French corpus by using different features2010In: Pervasive Computing, Signal Processing and Applications (PCSPA 2010), IEEE , 2010, p. 332-335Conference paper (Refereed)
    Abstract [en]

    The Oldenburg LOgatome speech corpus (OLLO) is specifically designed for evaluating speech recognition methods on variability. The performance of features carried on intrinsic variabilities in speech is meaningful for automatic speech recognition (ASR) system. ZCPA and MFCC were the two main features applied to OLLO French corpus in this paper. We took cepstral mean subtraction (CMS) on MFCC. Dynamic transforms (delta-delta-ZCPA and delta-delta-MFCC) were also adopted. The experiments show that the MFCC outperform the ZCPA in separate style. But ZCPA is more robust between different variabilities. The delta-delta operation of MFCC achieves best recognition in noise-free environment. Moreover, ZCPA could be complementary to MFCC so that one can combine them together especially on soft speaking style.

  • 32.
    Li-xia, Huang
    et al.
    Taiyuan University of Technology.
    Evangelista, Gianpaolo
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Media and Information Technology.
    Zhang, Xue-ying
    Taiyuan University of Technology.
    Adaptive bands filter bank optimized by genetic algorithm for robust speech recognition system2011In: Journal of Central South University of Technology, ISSN 1005-9784, E-ISSN 1993-0666, Vol. 18, no 5, p. 1595-1601Article in journal (Refereed)
    Abstract [en]

    Perceptual auditory filter banks such as Bark-scale filter bank are widely used as front-end processing in speech recognition systems. However, the problem of the design of optimized filter banks that provide higher accuracy in recognition tasks is still open. Owing to spectral analysis in feature extraction, an adaptive bands filter bank (ABFB) is presented. The design adopts flexible bandwidths and center frequencies for the frequency responses of the filters and utilizes genetic algorithm (GA) to optimize the design parameters. The optimization process is realized by combining the front-end filter bank with the back-end recognition network in the performance evaluation loop. The deployment of ABFB together with zero-crossing peak amplitude (ZCPA) feature as a front process for radial basis function (RBF) system shows significant improvement in robustness compared with the Bark-scale filter bank. In ABFB, several sub-bands are still more concentrated toward lower frequency but their exact locations are determined by the performance rather than the perceptual criteria. For the ease of optimization, only symmetrical bands are considered here, which still provide satisfactory results.

  • 33.
    Nguyen, Hoang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    A continuous wavelet-Galerkin method for the linear wave equation2007In: SIAM Journal on Scientific Computing, ISSN 1064-8275, E-ISSN 1095-7197Article in journal (Other academic)
    Abstract [en]

    We consider the continuous space-time Galerkin method for the linear second-order wave equation proposed by French and Peterson in 1996. A bottleneck for this approach is how to solve the discrete problems effectively. In this paper, we tackle this bottleneck by essentially employing wavelet bases in space. We show how to decouple the corresponding linear system and we prove that the resulting subsystems can be uniformly preconditioned by simple diagonal preconditioners, leading to efficient iterative solutions.

  • 34.
    Piccialli, A
    et al.
    University "Federico II" of Naples.
    Basile, P
    Evangelista, Gianpaolo
    University "Federico II" of Naples.
    Vergara, S
    Rappresentazione Tempo-Frequenza dei Segnali Digitali Basati sulle Trasformazioni Tempo-Scala1991In: Proc. of XIX Convegno AIA (Associazione Italiana di Acustica), 1991, p. 455-458Conference paper (Other academic)
  • 35.
    Polotti, P
    et al.
    École Polytechnique Fédérale de Lausanne.
    Evangelista, Gianpaolo
    École Polytechnique Fédérale de Lausanne.
    Fractal Additive Synthesis by means of Harmonic-Band Wavelets2001In: Computer Music Journal, ISSN 0148-9267, Vol. 25, no 3, p. 22-37Article in journal (Refereed)
  • 36.
    Raspaud, Martin
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Binaural partial tracking2008In: Proc. of Digital Audio Effects Conf. (DAFx'08), Helsinki, Finland: DAFx , 2008, p. 123-128Conference paper (Refereed)
    Abstract [en]

    Partial tracking in sinusoidal models have been studied for over twenty years now, and have been enhanced, making it precise and useful to analyse noiseless harmonic sounds. However, such tools have always been used in a monophonic (single channel) context. A method is thus proposed to adapt the partial tracking to the case of binaural signals. This gives a tool to perform spectral analysis of such signals, keeping relevant information from both left and right channels. Moreover, azimuth (position in the horizontal plane) information for each partial is gained using interaural cues, such as interaural time differences (ITDs) and interaural level differences (ILDs). The azimuth information can then be used as an attribute or as a constraint in the binaural partial tracking algorithm. Finally, some classification results using the azimuth of partials are presented.

  • 37.
    Raspaud, Martin
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Digital Media.
    Viste, Harald
    Widex AS.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Digital Media.
    Binaural Source Localization by Joint Estimation of ILD and ITD2010In: IEEE TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING, ISSN 1558-7916, Vol. 18, no 1, p. 68-77Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a binaural source localization method based on interaural time differences (ITDs) and interaural level differences (ILDs). The two cues, computed from a two-channel time-frequency representation, are combined in order to estimate the azimuth of sources in binaural recording. We introduce an individual parametric model for the ITD and ILD, and an average parametric model that sets us free from measurements of the subjects HRIRs for sound localization. We conduct several experiments to validate the proposed approach and show that it compares favorably with available techniques.

  • 38.
    Testa, I
    et al.
    Dipartimento di Scienze Fisiche,, Università di Napoli, Italy.
    Evangelista, Gianpaolo
    Dipartimento di Scienze Fisiche, Università di Napoli, Italy.
    Cavaliere, S
    Dipartimento di Scienze Fisiche, Università di Napoli, Italy.
    Physically Inspired Models for the Synthesis of Stiff Strings with Dispersive Waveguides2004In: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2004, no 7, p. 964-977Article in journal (Refereed)
    Abstract [en]

    We review the derivation and design of digital waveguides from physical models of stiff systems, useful for the synthesis of sounds from strings, rods, and similar objects. A transform method approach is proposed to solve the classic fourth-order equations of stiff systems in order to reduce it to two second-order equations. By introducing scattering boundary matrices, the eigenfrequencies are determined and their n2 dependency is discussed for the clamped, hinged, and intermediate cases. On the basis of the frequency-domain physical model, the numerical discretization is carried out, showing how the insertion of an all-pass delay line generalizes the Karplus-Strong algorithm for the synthesis of ideally flexible vibrating strings. Knowing the physical parameters, the synthesis can proceed using the generalized structure. Another point of view is offered by Laguerre expansions and frequency warping, which are introduced in order to show that a stiff system can be treated as a nonstiff one, provided that the solutions are warped. A method to compute the all-pass chain coefficients and the optimum warping curves from sound samples is discussed. Once the optimum warping characteristic is found, the length of the dispersive delay line to be employed in the simulation is simply determined from the requirement of matching the desired fundamental frequency. The regularization of the dispersion curves by means of optimum unwarping is experimentally evaluated.

  • 39.
    Testa, Italo
    et al.
    Università di Napoli.
    Cavaliere, Sergio
    Università di Napoli.
    Evangelista, Gianpaolo
    Università di Napoli.
    Sintesi delle corde vibranti: algoritmi basati su un modello dispersivo1997In: Proc. of XXV Convegno AIA (Associazione Italiana di Acustica), 1997, p. 81-88Conference paper (Other academic)
  • 40.
    Testa, Italo
    et al.
    Università di Napoli .
    Evangelista, Gianpaolo
    Università di Napoli .
    Cavaliere, Sergio
    Università di Napoli .
    A Physical Model of Stiff Strings1997In: Proc. of the Institute of Acoustics - Internat. Symp. on Music and Acoustics (ISMA ‘97), Vol. 19, p. 219-224Article in journal (Refereed)
  • 41.
    Viste, Harald
    et al.
    EPFL, Switzerland.
    Evangelista, Gianpaolo
    University of Naples.
    A method for separation of overlapping partials based on similarity of temporal envelopes in multichannel mixtures2006In: IEEE Transactions on Audio, Speech and Language Processing, ISSN 1558-7916, Vol. 14, no 3, p. 1051-1061Article in journal (Refereed)
    Abstract [en]

    In a situation where multiple sound sources are concurrently active, the signals of the individual sources often overlap in time and in frequency. This is particularly likely for voiced instruments where the frequencies of some of the partials of one single note coincide with the frequencies of some of the partials of another instrument playing a harmonically related note. A source separation algorithm suitable for musical applications must address the problem of overlapping partials. A method is proposed for the separation of overlapping narrow-band partials in multichannel mixtures. The method is based on the observation that, for many instruments, all the partials of a single note have similar temporal envelopes. For narrow band partials these similarities can be exploited in order to estimate demixing matrices in the frequency domain. Effectively, one can recover estimates of the original partials from a multichannel mixture where they overlap. The method is computationally efficient in that it works on highly downsampled narrow frequency bands. It performs well for closely spaced and colliding partials, and (to some extent) also for frequency modulations such as vibrato effects.

  • 42.
    Zhang, Xueying
    et al.
    Taiyuan University of Technology, China.
    Huang, Lixia
    Taiyuan University of Technology, China.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Warped Filter Banks Used in Noisy Speech Recognition2009In: Proc. IV Int. Conf. Innovative Computing, Information and Control (ICICIC-2009), 2009, p. 1385-1388Conference paper (Other academic)
    Abstract [en]

    The filter bank in the front-end of a speech recognition system mimics the function of the basilar membrane. It is believed that the closer the band subdivision is to human perception, the better the recognition results. This paper proposes the use of Warped Filter Banks (WFBs) to replace traditional FIR filter banks and validates its use for the recognition of noisy speech. The WFBs bandwidths can be warped by using a first-order allpass transformation replacing the unit delay. Different warped factors in the allpass function can make the different scaled filter banks. Experiments carried on isolated words for speaker independent speech recognition show that the recognition rate with our proposed WFBs has been effectively increased. 

     

     

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