Mike Rivers wrote:


It's really all about frequency response, no any single frequency
response curve accurately characterizes the sound of a microphone,
other than perhaps a true omni mic (and there are darn few of those).

Yep. Its the response as a function of frequency, angle of
incidence to the plane of the diaphragm and the rotation
angle about the axis.

I would dearly love to find some real data measurments,
taken at an incidence resolution of a few degrees, which
would disclose the spatial frequency response of any
directional mic but while we claim that it is such a big
factor, I have never seen and have looked hard, for any real
data to back that up.

I would be especially interested in such data from a few
well known mics for comparative analysis.

Intuition tells me that the on axis response is the
predominant factor and that the angular variations from that
are going to be a very similar function across microphones
of similar size but I need data (or the time to gather it
some day) to prove or disprove that.

The frequency response, magnitude and group delay,
encompasses the transient response. Any system's response
to the shortest transient is isomporphic to its frequency
response.

People usually think "phase" but for audio and I wish we
could change that. It's really group delay or time
dispersion that we hear and are interested in. Phase was of
interest for closed loop systems wherein the whole frequency
domain thing was developed and phase gave information about
stability, but for open loop systems and especially with
respect to perception it's all about dispersion or group
delay as a function of frequency.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein