The Eigenmic uses omni directional microphones on a solid sphere, so the directional sensitivity is due to diffraction on the surface sphere (like the Neumann M50), hence the patterns change with frequency. These can be processed into spherical harmonics or directly into directional patterns. There are a number of tradeoffs that must be made at low-frequencies (due to noise) and high frequencies (due to spatial aliasing).
Typical practice is the record the capsule outputs and then produce directional outputs directly on playback. I think you can download the processing software and manual from mh. Here are some papers. IMHO, [2] is the most readable as an introduction. [1] J. Meyer and G. W. Elko, “SPHERICAL MICROPHONE ARRAYS FOR 3D SOUND RECORDING,” *AUDIO SIGNAL PROCESSING FOR NEXT-GENERATION MULTIMEDIA COMMUNICATION SYSTEMS, Ch. 3*, pp. 1–23, 2004. [2] Z. Li, R. Duraiswami, and N. A. Gumerov, “Capture and Recreation of Higher Order 3D Sound Fields via Reciprocity,” *Proceedings of ICAD-04*, vol. July, p. 8, May 2004. [3] T. D. Abhayapala and D. B. Ward, “Theory and design of high order sound field microphones using spherical microphone array,” presented at the Acoustics, Speech, and Signal Processing (ICASSP), 2002 IEEE International Conference on, 2002, vol. 2. [4] A. O'Donovan, R. Duraiswami, and D. Zotkin, “Imaging concert hall acoustics using visual and audio cameras,” *Proc IEEE Int Conf Acoust Speech Signal Process*, pp. 5284–5287, Jan. 2008. Aaron Heller (hel...@ai.sri.com) Menlo Park, CA US On Thu, May 2, 2013 at 2:20 AM, Paul Power <pro_powe...@yahoo.co.uk> wrote: > Hi all, > Just wondering if anyone could give me any information on how the > Eigenmike works, since there is not allot of information available. I am > very familiar with the Soundfield mic and how it generates the directional > information W,X,Y, and Z through three FO8 patterns and an omni, this being > in the form of four audio signals which are combined in different > amplitudes and phase depending on speaker location, however regarding the > Eigenmike it generates 25 audio signals which corresponds to 4th order? I > understand that eigenbeams can be formed and pointed in any direction, > however what are the pick up patterns of each capsule? and does the signals > that you get from the mic correspond to say the way the Soundfield mic > works, (excuse my simplistic idea) for example are the first four channels > of the Eigenmike W,X,Y and Z for example? > > > Thank you in advance, Paul Power > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20130502/8ada69e8/attachment.html > > > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130502/973da2a3/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
