21 Jun
2011
21 Jun
'11
12:33 a.m.
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(a)linuxaudio.org>wrote;wrote:
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
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.