On Thu, Oct 15, 2015 at 03:59:46PM +0200, Jörn Nettingsmeier wrote: > We've seen all those outlandish claims of magical waveguides that > are just fractions of the wavelength in diameter and yet shape the > sound so wonderfully that a 20Hz beam will travel all the way to the > moon (using the revolutionary VacuProof™ technology that will > finally bring cinema-friendly space battles). The problem is, this > waveshaping is not physically possible.
Yes, it's a simple as that - not physically possible. If you think in ambisonic (spherical harmonic) terms it's easy to see why. Orders zero and one correspond to physical quantities, pressure and velocity, so these can be generated directly at any point. Higher order SH can't. Which means that you can have cardioid subs, or even supercardioid ones, but anything expected to create more directional beams will need to be of a size comparable to wavelenght. Can be (and is) done for open-air PA systems using very big arrays. But not in any normal room, there simply isn't the space to do it. 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.
