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Sunday, May 12, 14:00 – 18:00 h
Chair: Jörg Wuttke, Schoeps, Karlsruhe, Germany

14:00 h
K 1 Room-Acoustical and Technological Aspects for Classical Multichannel Sound Recordings Gerhard Steinke, Berlin, Germany

The more the quality increases on the part of studio engineering – i.e. microphones, pick-up technology, delivery, storage - the more some weakness is evident at the beginning and the end of the transmission chain:
(a) Recording studios for classical music mostly have not the required quality parameters for the artists and the information to be recorded. As one recommendable example the large recording hall in Berlin and its characteristics are discussed. Experiences with multichannel sound productions in this hall are covered.
(b) On the other side, standard listening conditions of control rooms - see AES document TD 1001.0.01-05 “Multichannel surround sound systems” – have to be considered from time to time to show open questions and the uncertain situation at home.
Convention Paper 5561

14:30 h
K2 Subjective Audio Quality Tradeoffs in Consumer Multichannel Audio-Visual Delivery Systems - Part I: Effects of High Frequency LimitationSlawomir Zielinski1, Francis Rumsey1, Søren Bech2 - 1University of Surrey, Guildford, UK; 2B&O, Struer, Denmark

The subjective effects of controlled high frequency limitation of the audio bandwidth on assessment of audio quality were studied. The investigation was focused on the standard 5.1 multichannel audio set-up (Rec. ITU-R BS.775-1) and limited to the optimum listening position. The effect of video presence on audio quality assessment was also investigated. The results of the formal subjective test indicate that it is possible to limit the high frequency content of the center or of the rear channels without significant deterioration of the audio quality for some of the investigated program material types. Video presence has small effect on audio quality assessment.
Convention Paper 5562

15:00 h
K3 Effect of Rear Microphone Spacing on Spatial Impression for Omnidirectional Surround Sound Microphone Arrays Francis Rumsey, Wyn Lewis, University of Surrey, Guildford, UK

The effect of rear microphone spacing in a five-channel omni-directional array was evaluated in respect of the subjective attributes ‘envelopment’, ‘spaciousness’ and ‘naturalness’. Preference results were also obtained and a range of different program material types was evaluated. Results suggest that, although large differences were not noticed, spacing has a statistically significant effect on envelopment and spaciousness, with spacings larger than the critical distance of the room giving rise to higher levels of these attributes. Distinct preference was shown for spacings of three and four metres as opposed to the extremes of two and five metres, in the particular acoustic environment tested, suggesting that beyond a certain microphone spacing the reproduced spatial impression becomes less pleasing or natural.
Convention Paper 5563

15:30 h
K4 Stereo and Surround Panning in PracticeDavid Griesinger, Lexicon, Bedford, MA, USA

The apparent position of speech and music sound sources was investigated using both a two channel loudspeaker array and a three channel loudspeaker array. The results showed that a sine-cosine pan law was reasonably accurate for the three channel array, but consistently produced images that were wider than expected with a two channel array. The discrepancy was investigated using a headphone model. We found the apparent position depends strongly on the spectrum of the source, with speech frequencies tending to dominate the overall impression.
Convention Paper 5564

16:00 h
K5 In the Light of 5.1 Surround: Why “AB-Polycardioid Centerfill” (AB-PC) is Superior for Symphony Orchestra RecordingEdwin Pfanzagl, Salzburg Festival, Salzburg, Austria

The reappearance of surround sound in the form of the DVD's 5.1 format has led sound engineers to re-evaluate current microphone techniques used for stereo recording.
The author has measured various 2-channel main-microphone signals in order to prove that their correlation is strongly frequency dependent. Due to properties of the human hearing mechanism as well as standard loudspeaker playback-arrangements frequencies below approximately 800 Hz are particularly critical in terms of faithful spatial reproduction in a stereo as well as 5.1 surround environment and therefore deserve special attention already during the recording process. Conclusions from the measurements are drawn and a microphone system (“AB-Polycardioid Centerfill”), well suited for 5.1 surround is proposed.

Convention Paper 5565

16:30 h
K6 A Microphone Array for Surround Sound RecordingCharles Fox1, Wade McGregor2 - 1University of Regina, Regina, Canada; 2MCSquared Systems Design Group, North Vancouver, Canada

The paper describes a multiple microphone array method and mounting system of a modular design. The Modular Microphone Array facilitates accurate and repeatable transducer configurations suited to a variety of studio and field recording situations and standards, including surround sound recording. The design supports a wide variety of transducer types (microphones) and is independent of any specific manufacturer's model or type. The novel overall shape, with attendant capability to be modified, is a further attribute. The light weight of this design ensures portability and ease of deployment in diverse field recording situations: musical performance recording, film and video production, broadcast, sound effects recording, ambient soundscape recording, and other professional audio applications.
Convention Paper 5566

17:00 h
K7 Multichannel Microphone Array Design: Segment Coverage Analysis Above and Below the Horizontal Reference PlaneMichael Williams, Sounds of Scotland, Le Perreux sur Marne, France

Individual Segment Coverage for a given Multichannel Microphone System is normally considered (if at all) only in the horizontal reference plane However, any microphone system has sound pick up throughout the spherical zone surrounding the microphone system. One must therefore know with reasonable precision the operational characteristics of any microphone system in use, at all angles of elevation to the reference plane, before being able to predict the localization of sound sources outside the reference plane, the distribution of the reverberant field, or the localization of early reflections within the reproduced sound image. Knowledge of these characteristics can also influence considerably the mechanical design of a variable microphone support system for multichannel microphone arrays.
Convention Paper 5567

17:30 h
K8 The Recording Angle – Based on Localization Curves Helmut Wittek, Günther Theile, Institut für Rundfunktechnik GmbH, München, Germany

The useful pick-up sector of a stereophonic microphone is indicated by the recording angle. It is based on phantom source shift data due to resulting inter-channel level and/or time differences. However, in related literature the recording angles of known microphones such as XY, Blumlein, AB, ORTF, OCT, etc. are differing because they are determined from different interpretations of these data. It is proposed to rest on the so-called localization curve, which describes the directional translation of sound sources within the loudspeaker basis and corresponds with directional balancing results in practical recording situations. The newly defined "Recording Angle_75%" is proposed to be the suitable key value in the Tonmeisters’ practice.
Convention Paper 5568

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