1,720,977 research outputs found
Ambiophonic Principles for the Recording and Reproduction of Surround Sound for Music
Full text linkThis paper discusses the psychoacoustical background and the computational issues involved in the real-time
implementation of a complete Ambiophonics reproduction system based on binaural technology. Ambiophonics,
which requires only two media channels, evolved from previously known approaches such as the reproduction of
binaural recordings over closely spaced loudspeakers through cross-talk cancellation, and the reconstruction of hall
ambience by convolution from suitable impulse responses. The equations for the design of the digital filter
coefficients are derived with regard to the many possible kinds of pre-existing recordings (binaural, sphere, ORTF,
M/S), and their implementation on available hardware and software platforms are described. The authors suggest
psychoacoustic explanations for the perceived audible performance, and describe the first results of a comparative
listening test, evaluating the realism of three periphonic surround reproduction systems: Stereo Dipole, Ambisonics
and Ambiophonics
In-Situ Measurements of Normal Impedance and Sound Absorption Coefficient of Hard Materials by using a Laser Doppler Vibrometer
No full textAspects of the measurement of the acoustic transfer function in a cavitation tunnel
No full textModel scale experiments represent one of the most effective, and probably the most commonly used, approaches
for the study of cavitating propeller noise. Despite this, the acquirement of consistent data of propeller noise
from tests in model scale facilities is still a challenging task. Data collected with such an approach are usually
affected by several scale effects and facility related issues which make such experiments still very complex.
Among others, the effect of the facility itself as acoustical surrounding must be carefully addressed in order to
properly estimate propeller source levels in ideal free field conditions. This is currently carried out, when
possible, by measuring facility transfer functions and applying such functions as a correction to measured noise
spectra. The development of robust procedures for the measurement of these transfer functions is thus very
important. In the present work, this problem is addressed by discussing in details techniques, merits and possible
problems related to this topic
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
Variations 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
Electric boat underwater radiated noise and its potential impact on species of conservation interest
No full textElectric boats are thought to be noiseless, but in-situ measurements are generally rare. The Underwater Radiated Noise (URN) of 8-m Trimaran Pontoon Boat with two outboard electric engines was measured in the Miramare Marine Protected Area (Trieste, Italy), together with the URN of a fibreglass 5-m boat, with a outboard gasoline engine, for comparisons. International standards and guidelines for shallow waters were considered. URN were provided in one-third octave band and in narrow band spectra. The electric boat produced a low input of underwater noise at low frequencies. Given a low-frequency hearing sensitivity, the listening space reduction (LSR) was lower when generated by the electric than by combustion engine boat for the brown meagre, a local Teleost fish. No difference was found for the bottlenose dolphin LSR although continuous, tonal, high frequency components generated by the electric boat are expected to be highly detrimental for the bottlenose dolphin
Cavitation tunnel acoustic characterisation and application to model propeller radiated noise measurements at different functioning conditions
No full textIn present work, an acoustic characterisation of the University of Genoa cavitation tunnel is presented, with the aim to obtain suitable transfer functions in order to take into account (at least partially) the effects of the confined environment, particularly important for small-scale facility like the one considered. The acoustic characterisation is performed considering two hydrophones in significantly different positions (inside the tunnel and in an external tank), typical, for different reasons, of noise measurements in cavitation tunnel; the procedure is based on the logarithmic sine sweep signal. The obtained transfer functions have been applied to a series of measurements of model propellers in correspondence to considerably different functioning conditions, in terms of cavitation number and propeller loading, showing the applicability of the procedure and the improvement of the measurement quality, in view of predictions in full scale
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