On Mon, Jun 20, 2011 at 04:41:46PM -0500, Charles Henry wrote: > On Fri, Jun 17, 2011 at 12:48 PM, Fons Adriaensen <fons@xxxxxxxxxxxxxx>wrote: > > > For a real single sound source the direction of the > > vector V(t) is that towards the source, and P(t) and > > V(t) in any given point are closely related. They are > > of course measured in different units (Pascal, and > > meters/second resp.), one is a scalar and the other > > a vector, but they are proportional. > > > This doesn't matter to the rest of your analysis/description, but I'd offer > a correction to this paragraph. > > V(x,t) is proportional to the spatial gradient of P(x,t). > > Note that this means pressure and velocity waves are 90 degrees out of sync > with each other. No, this is wrong. The gradient is 90 degrees out of phase w.r.t. pressure, and rises by 6 dB/oct w.r.t. pressure. The velocity vector is the time integral of the gradient, and consequently it is in phase with pressure, and the P/V ratio is independent of frequency (assuming far field). Ciao, -- FA _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
