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AES Amsterdam 2008
Poster Session P21

P21 - Multichannel Sound

Monday, May 19, 16:00 — 17:30
P21-1 Challenges in Reproduction and Evaluation of Upmixed Audio in an Automotive EnvironmentOliver Hellmuth, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Steffen Bergweiler, Manfred Neumann, Stefan Holzhäuser, Lear Corporation GmbH - Kronach, Germany; Andreas Walther, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
Audio systems with high quality sound reproduction capabilities are becoming more and more popular in the car. The need to create a pleasant sound field has lead to an increased number of loudspeakers combined with digital signal processing. To benefit from the advantages of surround sound reproduction also for two-channel legacy content an upmixing algorithm is required. In this paper challenges and requirements for high quality surround sound reproduction and upmixing are first introduced separately and then discussed jointly with the specific focus on the automotive environment. Finally a test method for the evaluation of different upmixing algorithms in the car is suggested.
Convention Paper 7452 (Purchase now)

P21-2 A General Approach to Methods for Loudspeaker Array SynthesisJuan Miguel Navarro Ruiz, Universidad Católica San Antonio de Murcia - Guadalupe, Murcia, Spain
Loudspeaker arrays are often used as sound reinforcement in large concert halls and outdoor events to provide increased directivity. Contrary to what happens in loudspeaker systems, there is an entrenched theory in antenna array synthesis, which has been used extensively over the past few years. This paper focuses on discussing several consolidated antenna array synthesis methods. Then, a simulation software is implemented to show pros and cons of using on loudspeaker arrays. Finally, an efficient synthesis method is proposed to achieve the required characteristics.
Convention Paper 7453 (Purchase now)

P21-3 On Large Multiactuator Panels for Wave Field Synthesis ApplicationsBasilio Pueo, University of Alicante - Alicante, Spain; José Escolano, University of Jaén - Linares (Jaén), Spain; José Javier López, Germán Ramos, Technical University of Valencia - Valencia, Spain
Wave Field Synthesis (WFS) is a spatial sound rendering technique that generates a true sound field using loudspeaker arrays. Multiactuator Panels (MAPs) are an alternative technology to the dynamic piston loudspeakers, based on the distribute mode operation. Because of its low visual profile and negligible vibration of the panel, MAPs are very suitable for WFS reproduction. However, the size of current prototypes does not allow its use for real immersing environments in which the loudspeaker must be integrated as walls or as projection screens. In addition, the extra area of a large panel can be used to accommodate extra exciters with which to generate sound fields at another elevation level. In this paper a very large MAP prototype is presented that has been designed and built to fulfill the requirements of immersive audio applications. It represents a step forward in the applications of MAPs for immersing scenarios. The panel size enhances its acoustic behavior in the low frequency range. Also, it can be employed for relatively large projection screens for videoconferencing and for virtual reality.
Convention Paper 7454 (Purchase now)

P21-4 Temporal Changes of Psychological Impressions Regarding Microphone Arrays for Multichannel RecordingToru Kamekawa, Atsushi Marui, Tokyo University of the Arts - Adachi-ku, Tokyo, Japan
Microphone technique for surround sound recording of an orchestra is discussed. Seven types of surround microphone sets recorded in a concert hall were compared in subjective listening test on attributes such as powerfulness and spaciousness using a method inspired by MUSHRA (MUltiple Stimuli with Hidden Reference and Anchor). To minimize temporal change in music, Phase Randomized Signal (PRS) was proposed. From the average score of the listening test, the impression difference between original source and PRS was found in some microphone arrays consisting of directional microphones at some pieces. It means that the impression of these arrays depend on temporal changes in music. The data from the listening test between the original source and PRS showed that impressions of powerfulness had slightly higher correlation. The relations of the physical factors of each array were also compared, such as SC (Spectral Centroid), LFC (Lateral Fraction Coefficient), and S/O (Side/Omni Ratio) of each array. The correlation of these physical factors and the attribute scores show that the contribution of these physical factors depends on music and its temporal change.
Convention Paper 7455 (Purchase now)

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