CLIOwin 7 PCI User's Manual - Audiomatica

Another factor of maximum importance in order to obtain the best results is to properly
set input sensitivity for both input channels separately; the two peak meters of
CLIOwin desktop should help you in this task; set input sensitivity so that both readings
average in their respective green areas. If you are taking as reference the line level signal
fed to the sound reinforcement system and are measuring from a microphone it is quite
common the situation in the following figure where the two input channels have
sensitivity which differ of 40dB or more.
When the measurement is started you will see the A/B magnitude frequency response
which is averaging on the screen and fast refreshing; sometimes you may notice, in
dependance of moments when sound is particularly low or absent, that the measurement
freezes and the Level Threshold display becomes red:
You may freely choose the most appropriate level threshold so that your measurement
accumulates only when signal is present; take into consideration that the threshold
relates to peak level vs. full input scale so it is not an absolute value but can be directly
compared with the CLIOwin desktop peak meters.
Another important indication about how good is your measurement is given by the
coherence graph.
The coherence function tells us in which frequency zones the energy content of the
measured signal relates, i.e. is coherent, with the reference signal; the more the signals
are coherent the more the coherence function approximates unity (or 100%); the less
they are coherent the function tends to zero. In figure above we may say that both in
the highest frequencies region (above 15kHz) and in the mid-bass region there are
zones of low correlation (