<div class="gmail_quote">On Fri, Jun 17, 2011 at 12:48 PM, Fons Adriaensen <span dir="ltr"><<a href="mailto:fons@linuxaudio.org" target="_blank">fons@linuxaudio.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
For a real single sound source the direction of the<br>
vector V(t) is that towards the source, and P(t) and<br>
V(t) in any given point are closely related. They are<br>
of course measured in different units (Pascal, and<br>
meters/second resp.), one is a scalar and the other<br>
a vector, but they are proportional. </blockquote><div><br>This doesn't matter to the rest of your analysis/description, but I'd offer a correction to this paragraph.<br><br>V(x,t) is proportional to the spatial gradient of P(x,t).<br>
<br>Note that this means pressure and velocity waves are 90 degrees out of sync with each other. <br>One clear case this matters is the boundary conditions at walls. The volume velocity goes to 0 at the wall (Dirichlet), but the pressure has the requirement that its 1st derivative is 0 (Neumann). <br>
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