Contrasting ITU 5.1 and Panor-Ambiophonic 4.1 Surround Sound Recording Using OCT and Sphere Microphones

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^Updated 11/02/03^

Ambiophonics
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Contrasting ITU 5.1 and Panor-ambiophonic 4.1 Surround Sound Recording Using OCT and Sphere Microphones
by Robert E. (Robin) Miller III ©2002, FilmakerStudios, Bethlehem, PA 18018 USA
Page 4

For fair comparison, 5.1 and PanAmbio recordings were made simultaneously, both in the concert hall and the studio, using best practices in the experience of the author: OCT and dual Ambiophone (essentially two sphere microphones with acoustic baffle) comprised of small diaphragm condenser microphones (Figure 12). For ITU 5.1, the OCT array consisted of five microphones: a cardioid and two supercardioids optimized for off-axis pickup mixed with omnis to support bass reproduction. For the opera, a spot microphone was mixed according to the Room Related Balancing technique [6]. Figures 13, 14, 15 show the main array and its placement.

Fig. 12. Microphone arrays contrast two 360ƒ reproduction methods. PanorAmbiophony uses twin spheres with baffle. OCT uses two supercardioids facing ±90ƒ and cardioid facing front. Simultaneous recordings of guitar quintet + fans, opera, brass quintet, string quartet, marching bands, and "Perambiolating 360ƒ" azimuth test were authored to companion DTS-encoded CDs for evaluation [13]. [back]

Fig. 13. Guitar quintet in studio for comparison 360ƒ recordings. OCT and prototype Ambiophone are at right. Instrumentalists are at 0ƒ, ±30ƒ, ±60ƒ and fans (not shown) at ±75ƒ, ±105ƒ, ±120ƒ, ±150ƒ. [back]

Fig. 14. OCT atop prototype "PanorAmbiophone" ñ twin sphere microphones separated by baffle. In the studio, the rear sphere also served as room microphone for OCT. [back]

Fig. 15. Hoisting OCT and prototype Ambiophone microphones in the 1,000 seat opera house. Microphones are Schoeps CCM-series. [back]

5.1 and PanAmbio mixes were made of all six recordings and encoded on DTS audio CDs for convenient replay for demonstrations and future listener tests. For music, no equalization, effects, or dynamic compression was used. In informal listening sessions, independent recording engineers and musicians involved in the recordings reported generally that, with both reproduction systems, the recordings were among the most realistic they had heard, and that in particular the localization of PanAmbio was the most accurate. We hope to verify these conclusions in future formal listening tests using trained auditioners [16]. Observing the highly accurate indication of positioning of instruments and vicarious enjoyment of the "live" performance by these critical listeners, the author feels it is safe to claim that, using these techniques, both ITU 5.1 and PanAmbio 4.1 are significantly more satisfying than conventional stereo in the realism and natural reproduction of music.

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