Hi all a quick comment on ideal line sources: The free-field impulse response of an ideal line source (as Dave suggested, an infinite line of monopole sources, with same phase and amplitude and infinitely closely spaced) is the free-field Green function of the wave equation in 2D (in the freq domain is more or less a Hankel function H_0(kr) - NOT the spherical Hankel functions we use for near field compensation).
Looking at this impulse response (time domain), one may surprisingly find out that it does not look like a delta function at all, but has an infinite decay after the initial wave.... If you think at the physics of the line of monopoles, this might become more logical.... This was quite surprising to me when I first realized that (and then was even more surprised when looked at the 1D Green function - it's a Heaviside step function!) Anyway, I believe that Ambisonics decoding with line sources is the same as with monpole-like sources if we make the assumption of far field (they are all plane waves). Otherwise, if you really want to apply a near field compensation (do you?), then it is pretty much the same as for the 3D case (monopoles) but substituting the spherical Bessel/Hankel (j_n / h_n) functions with traditional Bessel/Hankel functions (J_n / H_n) [Richard, I know what you are thinking....yet again, I couldn't help but mention the Hankel functions...sorry :-) ] Regards, Filippo _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
