Polycom SoundStructure C16 Design Manual page 230

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
The microphones "Table Mic 1 A" through "Table Mic 4 C" are routed to the
"VTX1000 Out" channel using the conferencing signal path which includes
echo and noise cancellation, and automixer processing. The blue background
of these crosspoints is the visual indicator that the conferencing version of the
input processing has been selected.
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