Ambisonic sound recording is predicated on the acquisition of audio signals in what has been termed “B-format”, which is the output of a microphone array known as the Soundfield Microphone. That microphone is a tetrahedral array of nominally cardioid microphone capsules. The capsule signals are processed in such a way as to give four output signals which are proportional to the pressure and the three-dimensional particle velocity vector at the center of the array. These same signals can be achieved by the use of a single omnidirectional microphone and three figure-of-eight microphones located close to each other. Errors in the shape of the polar pattern or in the ratio of the direct to diffuse-field sensitivity of the microphones result. The two methods are compared in both a theoretical analysis and in acoustical measurements. The results of the comparison of experimental recordings using these two types of arrays will be presented in part two of this paper.
Benjamin, Eric; Chen, Thomas
Affiliations: Dolby Laboratories; Studio C(See document for exact affiliation information.)
AES Convention: 119 (October 2005) Paper Number: 6621
Publication Date: October 1, 2005
Subject: Microphones & Internet Audio
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