Telephony Signal Levels - Polycom SoundStructure C16 Design Manual

When two mono AEC references are used, or a stereo virtual channel is used as the reference as shown in
the following figure, there are two room gain indicators, one for each reference.
Two Room Gain Indicators
-10 -7 -4 -1 2
-10 -7 -4 -1 2
The room gain measurements and guidelines for the two reference applications are similar to the single
AEC reference example. If either reference shows a high room gain, review the gain settings for the AEC
references and audio amplifier, check the microphone to loudspeaker coupling, and adjust remote audio
input levels as necessary to achieve an acceptable room gain level, as described previously.

Telephony Signal Levels

The telephony inputs and outputs have an analog input gain that can be adjusted to create the required
signal level on the telephone receive path. The following figure shows the input and output signal meters
and where they appear within the user interface of the SoundStructure Studio software.
The Phone In gain adjusts the analog signal level coming in from the phone line. Any adjustments made to
the analog input gain is reflected in the meter activity of the Phone In channel. Adjust the phone in gain so
that the remote talkers peak level lights at least the second yellow LED and flickers the LEDs above that.
Depending on the PBX or the Central Office connection, this could be a gain in the range of 0 to 6dB. Up to
20dB of gain may be applied at the phone input gain.
The Phone Out fader adjusts the signal level transmitted to the phone line. Any adjustments made to the
output fader is reflected in the meter activity of the Phone Out channel.
Polycom, Inc.
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