From literature we know, that a micro-
phone’s random (diffuse) incidence
response can be approximated by
measuring the 90 deg incidence re-
sponse relative to a single sound
source.
While it is an approximation only iSEM-
con has measured the 90deg response
of many EMX-7150 microphones and
used the averaged data to evaluate a
19
th
order polynomial. This is now used
to derive the “diffuse field” response
from the microphones free field re-
sponse data.
Typical freefield measurement:
Speaker measurement. The micro-
phone should target to the sound
source (speaker).
Typical diffusefield meas-
urements:
Concert SPL monitoring
(normally at FOH), Room
Acoustics measurement
(RT60): the microphone
should not target to the
sound source. Let it target
to the ceiling. This is the
most practical way.