USB Measurement Microphones level calibration
At
this point we would like to summarize some general information on the subject at
level calibration of measurement microphones.
The classic setup for PC measurement system consists of
 |
Measurement Software |
|
USB sound card with phantom power P48 |
|
Measurement microphone (electret with phantom power) |
|
Sound level calibrator |
If
you connect
and configured everything properly and
starts to measure the sound level, the software will usually display something
negative, such as -33.5dB (A).
Typically, this
is the level with respect to the full-range
of the AD
converter and has nothing to do with the absolute sound level
First,
we need to
calibrate the entire measurement chain : This can be done with a handheld sound
level meter, place
it close to the microphone
(not very precise),
or with a sound level calibrator (expensive).
Unfortunately,
you have to this this again once
you touched the gain on the sound card or mixer for Windows.
The setup
is no longer calibrated.
In addition, overload conditions are difficult to detect since all the signal stages are unknown. Actually, a full measurement would be required to document the maximum and minimum level ranges.
It is already evident from this brief description that you have to be very careful when you measure the sound level. Beginners fall regularly in several major pitfalls and even professionals have quickly forgotten a little thing, and this causes a measurement with significant errors.
We
believe,
that our new
USB measurement
microphones solves all these problems.
Finally, we are at the point:
Install
the software, connect the
microphone,
launch the software
and measure immediately calibrated absolute sound
levels.
This
is possible, because software, microphones, preamps, and soundcard are one
unit.
Everything
is calibrated by the manufacturer.
The
software also controls the gain
of
the windows mixer. Furthermore,
the measurement
ranges
are displayed correctly, so you know which level ranges
can be measured correctly. The
measuring ranges can be selected simply by a
mouse
click. Over-
and underload
conditions are
displayed correctly
.
Ultimately,
these are all things that you
expect from hand sound level meter
since many years, no
matter what price range. And consequently you can expect this from
high quality PC-measuring systems as well.
For
reliable measurements of
course,
you can will need a calibrator.
But
it serves
only (as with any hand sound
level meter)
for the periodic review and not to get rough values.
Note:
The
USB measurement microphones,
that are currently on the market, are all USB audio class compliant.
Therefore
work with any software, but the above-described automatic level calibration,
work only on systems where software and microphone are perfectly matched
and the software controls also
the
Windows
mixer. This
is obviously the case with our complete
solutions.