On Fri, Nov 01, 2013 at 11:14:07AM -0200, Iain Mott wrote: > I've been reading a paper recently "B-Format Acoustic Impulse Response > Measurement and Analysis in the Forest at Koli National Park, Finland" > by Simon Shelley, Damian Murphy and Andrew Chadwick, where a > unidirectional loudspeaker is used to collect IRs via a > sine-sweep/de-convolution method. To simulate an omnidirectional source, > four recordings are made of the sweep with the loudspeaker directed at > the mic and at 3 other positions 45 degrees apart. > > The IRs for the simulated omnidirectional source are created by: > > "summing the resulting impulse responses measured for each angle of the > loudspeaker. The effect of the summation is to emulate a loudspeaker > array of four loudspeakers at the same point in space all pointing in > different directions." > > So, my first question is, is this "summing" really a simple summation of > the 4 sets (a b-format mic is used) of IRs with some attenuation of > each, or would there be something more complex involved?
No, a simple sum would be all that is required. But the IRs need to be aligned correctly in time. > I'm interested in spatialising the human voice with IRs - and a > directional source is probably more appropriate than an omnidirectional > one. The above got me thinking though, if it is a simple sum, wouldn't > it be possible to simulate the variable orientation of a speaker (human) > by doing an equal power crossfade between adjacent angular IRs as this > virtual human speaker turns? That is mathematically not correct, but I'm pretty sure it would work in practice, in particular if you process the direct sound separately (e.g. by filtering in function of the direction the speaker is facing). 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
