Room Gain - Polycom SoundStructure C16 Design Manual

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12

Room Gain

8 - 12
Room gain meters are used to measure the relative level of the remote audio
that is present at the input to the AEC with the level of the echo that is present
at the microphone. For more information on room gain and how it is mea-
sured, see Appendix C.
The room gain meter is shown on the AEC portion of the input channel on the
channels page as shown in the following figure. The meter segments show the
room gain ranges in 3dB increments from -10 to +20dB. The first segment of
the meter is lit if the room gain is greater than -10dB and less than or equal to
-7, and so on through the meter segments. The last meter segment will illumi-
nate if the room gain is greater than 17dB.
The following figure shows different room gain measurements that may be
found in a typical room. Room gain is considered good if it is negative, mean-
ing that the echo picked up by the microphone is less than the level that is
output to the amplifier. Acceptable room gain occurs when the room gain is
less than +10dB. Not acceptable room gain occurs when the room gain exceeds
+10dB.
Acceptable
Not Acceptable
Tabletop microphone applications will typically have room gains that are 0 or
less while ceiling microphone applications will typically have room gains that
will be positive due to the proximity of the loudspeakers and ceiling
microphones.
-10 -7 -4 -1 2 5 8 11 14 17
Good
-10 -7 -4 -1 2
-10 -7 -4 -1 2
-10 -7 -4 -1 2
5 8 11 14 17
5 8 11 14 17
5 8 11 14 17