Polycom realpresence 1800 Administrator's Manual page 131

Defining SVC and Mixed CP and SVC Conference Profiles
10 Click the Audio Settings tab.
11 If required, define the Speaker Change Threshold: 1.5, 3, or 5
Auto (Default, 3 seconds), .
It indicates the amount of time a participant must speak continuously before becoming the speaker.
Polycom®, Inc. 100