I truly appreciate your informative and highly detailed response. For helping understand spherical harmonics (or Legendre polynomials?), and for mics lying on surface of a sphere, this helps a lot.
But here's what I don't understand about the quaud (quaud.io) mic: They say the four omnidirectional mics lie on the corners of a tetrahedron--essentially same arrangement as Soundfield, but with omni mics and positioned on corners of tetrahedron. Re mics on a sphere: In a corner-oriented tetrahedral arrangement, the mics would lie on a *virtual* sphere just as much as mics on a sphere could be lying on a virtual tetrahedron. But at some point the actual (physical) surface becomes a piece of the whole. This is clearly evident when the sphere is large enough to be a human head. So I'm not always clear as to whether it's the mics' virtual orientation in space, or the physical boundary of a spherical surface, that *shapes* the sound and creates the requisite time and pressure differentials. Dave M's original post states that someone else is... again... re-inventing the Soundfield mic. I'm sure that I'm not the only person who is curious as to what makes the quaud (Trademark) mic *unique* and different from the Soundfield mic--particularly if the quaud mic is patented. Is, for example, more than one tetrahedral arrangement used to achieve *surround* spacing--which would then be a wholly different thing? I need to read further. Thanks again for info. The following was cut-and-pasted from their website (I think Dave provided all of this in his post, too): quaudio comprises four omnidirectional microphones located at or near to the corners of a regular tetrahedron. Since these capsules are omnidirectional they can be located at the opposite corners of a cube with no loss in generality. This arrangement is straightforward to achieve in a standard PCB assembly line by soldering two pairs of MEMS or electret capsules on opposite sides of the substrate. Alternatively it is possible to solder three capsules to one side and a single capsule to the other. In both cases the acoustic centre of each sensor should be separated laterally by a distance corresponding to the vertical separation between membranes on either side of the device -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130420/263f0c70/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
