Polycom C16 - Manual (Page 310)

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
10 - 2
Is the amplifier turned on? Can other sources of audio be heard in the local
room? Add a Signal Generator from the Edit Channels control and route the
signal generator to the amplifier virtual channel.
Check that the wiring for the amplifier virtual channel on the wiring page
matches how the system is actually wired.
Check that the audio from the remote participants is not muted either locally
or at the remote site.
Remote Participants Can’t Hear Local Participants
Check that the audio from the local participants is routed through the matrix
to the remote participants.
Are the microphones unmuted? Can microphones be routed to the amplifier
(lower the gain at the crosspoint!) and the microphones heard in the local
room?
Check that the wiring for the remote virtual channels on the wiring page
matches how the system is actually wired.
Feedback Elimination Doesn’t Seem To Be Operational - Feedback Can Be
Heard Locally
Ensure the feedback eliminator is enabled on the microphones being used for
reinforcement as shown in the following figure.