On Wed, Apr 06, 2022 at 04:13:57PM +0300, Sampo Syreeni wrote: > With near field sources, the outwards radiating field from a point source > is reactive at each point. Pressure and velocity are *not* in phase,
Even a pantophonic mic will pick that up that phase difference. > the vector describing energy transfer (in EM I think the Poynting vector) > is *not* in the plane, but outwards from the source, all round. Which means that whatever you try to describe here is NOT a vector. The velocity vector will be in the horizontal plane, and is represented correctly by X,Y. It has no Z component. > So what happens is that while the > pressure field is fully symmetric in the horizontal plane, there still has > to be a Z component in order to recreate the field to full first order. Not for it to be correct for a listener in the same horizontal plane as the speakers. Of course if the listener moves up or down the sound field he/she senses will be incorrect. What do you expect ? > ...and that's precisely why pantophony is an idea born dead. We don't have > infinite vertical line sources, nor microphone arrays which mimic their > directional patterns. The only thing we really have is 3D mic arrays and 3D > rigs. Indeed. But we also have situations in which most sources are in the horizontal plane or close to it, and as listeners we tend to stay on the ground and not fly around. Ciao, -- FA _______________________________________________ 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.
