2,421 research outputs found

    Online Correction of Dispersion Error in 2D Waveguide Meshes

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    An elastic ideal 2D propagation medium, i.e., a membrane, can be simulated by models discretizing the wave equation on the time-space grid (finite difference methods), or locally discretizing the solution of the wave equation (waveguide meshes). The two approaches provide equivalent computational structures, and introduce numerical dispersion that induces a misalignment of the modes from their theoretical positions. Prior literature shows that dispersion can be arbitrarily reduced by oversizing and oversampling the mesh, or by adpting offline warping techniques. In this paper we propose to reduce numerical dispersion by embedding warping elements, i.e., properly tuned allpass filters, in the structure. The resulting model exhibits a significant reduction in dispersion, and requires less computational resources than a regular mesh structure having comparable accuracy.Comment: 4 pages, 5 figures, to appear in the Proceedings of the International Computer Music Conference, 2000. Corrected first referenc

    Signal-Theoretic Characterization of Waveguide Mesh Geometries for Models of Two--Dimensional Wave Propagation in Elastic Media

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    Waveguide Meshes are efficient and versatile models of wave propagation along a multidimensional ideal medium. The choice of the mesh geometry affects both the computational cost and the accuracy of simulations. In this paper, we focus on 2D geometries and use multidimensional sampling theory to compare the square, triangular, and hexagonal meshes in terms of sampling efficiency and dispersion error under conditions of critical sampling. The analysis shows that the triangular geometry exhibits the most desirable tradeoff between accuracy and computational cost.Comment: 9 pages, 6 figures, 1 table, to appear on IEEE Transactions on Speech and Audio Processing, vol. 9, no. 2, february 200

    Training binary neural networks without floating point precision

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    The main goal of this work is to improve the efficiency of training binary neural networks, which are low latency and low energy networks. The main contribution of this work is the proposal of two solutions comprised of topology changes and strategy training that allow the network to achieve near the state-of-the-art performance and efficient training. The time required for training and the memory required in the process are two factors that contribute to efficient training.Comment: 74 pages, Master's thesi

    Auditory navigation with a tubular acoustic model for interactive distance cues and personalized head-related transfer functions: an auditory target-reaching task

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    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 head-related 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 cues. HRTF personalization was beneficial for participants who were able to perceive vertical dimension of a virtual sound. Further work is needed to add full physical consistency to the proposed auditory display

    BIVIB: A Multimodal Piano Sample Library Of Binaural Sounds And Keyboard Vibrations

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    An extensive piano sample library consisting of binaural sounds and keyboard vibration signals is made available through an open-access data repository. Samples were acquired with high-quality audio and vibration measurement equipment on two Yamaha Disklavier pianos (one grand and one upright model) by means of computer-controlled playback of each key at ten different MIDI velocity values. The nominal specifications of the equipment used in the acquisition chain are reported in a companion document, allowing researchers to calculate physical quantities (e.g., acoustic pressure, vibration acceleration) from the recordings. Also, project files are provided for straightforward playback in a free software sampler available for Windows and Mac OS systems. The library is especially suited for acoustic and vibration research on the piano, as well as for research on multimodal interaction with musical instruments

    Evidence of Lateralization Cues in Grand and Upright Piano Sound

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    In a previous experiment we have measured the subjective perception of auditory lateralization in listeners who were exposed to binaural piano tone reproductions, under different conditions (normal and reversed-channel listening, manual or automatic tone production by a Disklavier, and disclosure or hiding of the same keys when they were autonomously moving during the automatic production of a tone.) This way, participants were engaged in a localization task under conditions also involving visual as well as proprioceptive (that is, relative to the position and muscular effort of their body parts) identification of the audio source with the moving key, even when the binaural feedback was reversed. Their answers, however, were clustered on a limited region of the keyboard when the channels were not reversed. The same region became especially narrow if the channels were reversed. In this paper we report about an acoustic analysis of the localization cues conducted on the stimuli that have been used in the aforementioned experiment. This new analysis employs a computational auditory model of sound localization cues in the horizontal plane. Results suggest that listeners used interaural level difference cues to localize the sound source, and that the contribution of visual and proprioceptive cues in the localization task was limited especially when the channels were reversed

    A nonlinear digital model of the EMS VCS3 voltage-controlled filter

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    This article presents a nonlinear discrete-time model of the EMS VCS3 voltage-controlled filters. The development of the model is based on the study of the filter circuitry and its behavior in the time domain. From this circuitry a system of nonlinear differential equations has been derived describing the dynamics in regime of large signals. The digital implementation of the filter is based on a numerical approximation of those equations. The resulting Matlab model has been compared with a structurally identical simulation running under PSpice. Finally, a real-time realization of the VCF has been implemented under the Pure Data processing environment

    Maximum Search Using P Systems

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    Several algorithms of maximum search are investigated and eval- uated in different types of P systems, namely using priorities, multiple nested membranes and linked transport. The proposed solutions are expected to find application in a wide range of problems. In particular, the authors are currently working on modeling an algorithm for DNA sequence alignment using P systems

    Discrete Solution of Differential Equations by P Metabolic Algorithm

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    The relationships existing between MP graphs, metabolic P systems, and ODE systems are investigated. Formal results show that every MP system, once derived by its MP graph, results in an ODE system whose solution equals, in the limit, the solution obtained by a non-cooperative MP system that is ODE equivalent to the original one. The freedom of choice of the ODE equivalent from the original MP system resembles the same freedom which is left in the choice and optimization of a numerical scheme while computing the solution of an ODE system

    Modeling of supramolecular biopolymers: Leading the <i>in silico</i> revolution of tissue engineering and nanomedicine

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    Abstract The field of tissue engineering is poised to be positively influenced by the advent of supramolecular biopolymers, because of their promising tailorability coming from the bottom-up approach used for their development, absence of toxic byproducts from their gelation reaction and intrinsic better mimicry of extracellular matrix nanotopography and mechanical properties. However, a deep understanding of the phenomena ruling their properties at the meso- and macroscales is still missing. In silico approaches are increasingly helping to shine a light on questions still of out of reach for almost all empirical methods. In this review, we will present the most significant and updated efforts on molecular modeling of SBP properties, and their interactions with the living counterparts, at all scales. In detail, the currently available molecular mechanic approaches will be discussed, paying attention to the pros and cons related to their representability and transferability. We will also give detailed insights for choosing different biomolecular modeling strategies at various scales. This is a systematic overview of tools and approaches yielding to advances at atomistic, molecular, and supramolecular levels, with a holistic perspective demonstrating the urgent need for theories and models connecting biomaterial design and their biological effect in vivo
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