1,720,977 research outputs found
Transducer Distribution on Spherical Arrays for Ambisonics Recording and Playback
No full textMicrophone and loudspeaker arrays are nowadays more and more employed in several applications, such as automotive industry, entertainment, immersive teleconferencing, or remote assistance. The position of the transducers over the surface of the array has a great influence on the beamforming, and so on the spatial performance. In this paper, a recurring geometrical problem is discussed: choosing the optimal locations of transducers for spherical arrays, either microphones or loudspeakers.None of the existing systems is currently relying on a spherical design, or t-design, for the arrangement of the transducers on the sphere. It will be shown that such mathematically optimized geometry is an optimal solution for the design of spherical arrays. They are the only known geometries ensuring a lossless transformation back and forth between the two most common spatial audio format: Ambisonics, which makes use of spherical harmonics, and Spatial PCM Sampling, which relies on unidirectional, high directivity virtual microphones
Experimental analysis of spatial properties of the sound field inside a car employing a spherical microphone array
No full textEstimation of Diagonal Volterra Kernels of an Audio System During Normal Operation with Multiple Least Mean Squares Adaptive Filters
No full textThe usage of Complete Volterra Kernels for emulating the nonlinear behavior of sound systems has been investigated for decades. Due to the computational load, the real-time implementation is typically limited to second order distortion and not feasible for higher orders. This is usually unsatisfactory for audio systems in which the disturbing distortions occur mostly at orders three and five. The same authors of this work already solved the problem with the Diagonal Volterra Kernels technique, which allowed to model arbitrarily high distortion orders. The estimation of the coefficients was obtained by exciting the system with an Exponential Sine Sweep signal. However, the result was often suboptimal since the signal reproduced by the sound system is usually different from a sinusoid. In this paper, a new method for estimating the Diagonal Volterra Kernels coefficients is proposed, by employing any music, noise or speech signal being played by a sound system in real-time. Multiple Least Mean Square algorithms are used to estimate the coefficients up to the 5 th distortion order, thus allowing to emulate the nonlinearities of a typical audio system
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Recording, Simulation and Reproduction of Spatial Soundfields by Spatial PCM Sampling (SPS)
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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