1,720,965 research outputs found
SPATIAL SOUND RECORDING WITH DENSE MICROPHONE ARRAYS
No full textMultichannel recordings are usually performed by means of microphone arrays. In many cases "sparse" and discrete microphone arrays are used, where each microphone is employed for capturing one of the channels, which in turn is routed to one loudspeaker.
However, also the usage of "dense" microphone arrays has a long history, dating back to the first MS-matrixed microphones setups and passing through the whole Ambisonics saga.
A dense microphone array is employed differently from a sparse array: each channel is obtained by a combination of the signals coming from all the capsules, by means of different matrixing and filtering approaches. And similarly, each loudspeaker feed results from a re-matrixing of all the transmitted channels.
This paper is the third of a series: in the previous two [1,2] a numerical method for computing a matrix of FIR filter was employed for processing the microphone signals (encoding, [1]) and for computing the speaker feeds (decoding, [2]). In this third paper, the same numerical approach is extended to intermediate processing (rotation, zooming, stretching, spatial equalization, etc.): hence we have now a general meta-theory, providing a unique framework capable of processing the signals for any kind of dense microphone array, providing any kind of intermediate manipulation, and finally projecting the signal to every kind of loudspeaker arrays. The same framework can operate according to different standards and formats, including A-format (raw signals), B-format (High Order Ambisonics signals), G-format (speaker feeds) and P-format (Spatial PCM Sampling signals), and can be used for converting freely among them.
Experimental results are presented, including "traditional" tetrahedral probes, a commercial spherical microphone array, and two newly-developed massive microphone arrays developed by the authors, a cylindrical and a planar array, both incorporating 32 high-quality condenser microphones and a panoramic video camera
Spatial analysis of room impulse responsescaptured with a 32-capsules microphonearray
No full textABSTRACT
The authors developed a new measurement system, which captures 32-channels impulse responses by means of a
spherical microphone array and a matrix of FIR filters, capable of proving frequency-independent directivity
patterns. This allows for spatial analysis with resolution much higher than what was possible with obsolete sumand-
delay beamforming.
The software developed for this application creates a false-colour video of the spatial distribution of energy,
changing with running time along the impulse response duration. A virtual microphone probe allows to extract the
sound coming from any specific direction. The method was successfully employed in three concert halls, providing
guidance for correcting some acoustical problems (echo, focusing) and for placing sound reinforcement
loudspeakers in optimal positions
Recording and playback techniques employed for the Urban Sounds project
No full textThe “Urban Sounds” project, born from a cooperation of the Industrial Engineering Department - University of
Parma with the municipal institution La Casa della Musica, aims to record characteristic soundscapes in the town of
Parma with a dual purpose: delivering to posterity an archive of recorded sound fields to document Parma in 2012,
employing advanced 3D surround recording techniques, and creation of a “musical” Ambisonics composition for
leading the audience through a virtual tour of the town.
The archive includes recordings of various “soundscapes”, such as streets, squares, schools, churches, meeting
places, public parks, train station, airport and everything was considered peculiar of the town. This paper details the
advanced digital sound processing techniques employed for recording, processing and playback
Experimental analysis of spatial properties of the sound field inside a car employing a spherical microphone array
No full textImplementing a spherical microphone array to determine 3D sound propagation in the 'Teatro 1763' in Bologna, Italy
No full textA new method for recording the spatial properties of a soundfield, or for generating a synthetic
three-dimensional soundfield, is described. The spatial distribution of sound waves passing at a
point in space is sampled by means of a number of virtual directive microphones, covering the
surface of a sphere. This corresponds to a discretization of the spatial information, which is
exactly the spatial equivalent of the PCM sampling of a waveform.
The paper shows how it is possible to obtain information about the direction of early reflections
in a theatre, not only by means of a 32-channels microphone, but also by means of traditional Bformat microphone (Soundfield). The method is applied to a historical Italian theatre, located in
Bologna, i.e. the 1763 theatre in Villa Mazzacorati.
The post processing includes the visualisation of the early reflections on a panoramic picture of
the theatre, in which early reflections are reported as different circles on the figure, where the
dimension and the intensity are related with the characteristics of the reflections.
Moreover, the influence of the height of the microphone in the calculation of the acoustic
parameters was analysed. The measurements were repeated at different height and different
position on a transversal line in the theatre, and statistically analysed
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
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