On Sun, Dec 06, 2015 at 06:48:25PM +0000, Stefan Schreiber wrote: > Fons Adriaensen wrote: > >No matter what type of mic you place behind such a tiny hole, it > >will pick up the pressure at that tiny hole. So apart from > >diffraction effects the result will be omni. > > > > But the pressure will come from -90º to +90º, at least mainly? If > so, the capsule "view" is 180º, not 360º. (Case as shield)
It acts as a 'shield' only at higher frequencies, as you can see in the plots. And then there is the peak at 180 degrees, the result of all parts of the wave travelling around the sphere arriving there exactly in phase. > Serious question: Is this not (more or less) a cardioid response?! Take for example the 8kHz response, which is the most directive one in the set. It's something like 3.5 dB down at 90 degrees. Apart from the narrow peak at the back, that's subcardioid. > >This produces a usable fig-8 up to 1 kHz or so (with lower > >frequencies requiring additional gain). Above that, chaos > >takes over. Using more mics (e.g. the four frontal ones > >minus the four at the back) will not improve things. > > ... > > But if it IS a hedgehog based mike, this is no issue. It is. If the video from the OZO is viewed on VR glasses (so the viewer can face *any* direction and even tilt his head sideways) then the audio needs to be in a format that has no preferred directions and that can be rotated to any attitude, in order to follow the viewer's motions. The 'hedgehog' doesn't produce anything like that, nor is it meant to. As Theile says himself in the paper, it is not designed to provide non-horizontal directional information, but to fill the top hemisphere with uncorrelated signals. This is more or less the opposite of what would be required. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
