Audio Source 

The sound on the speaker system will be the most recently selected content source from the touch screen.
 
As an example: You want to show a video cassette on the left screen while showing something from a computer on the right. You selected the computer first, and then the VCR. The VCR sound will be played over the speakers. To change audio sources, press the video window in which the source is displayed and then the button of the source.
 

The Document Camera is an exception to this rule. After pressing the "Select the DOC CAM" button, you will continue to hear whatever source was previously selected.

If the projector is not turned on, the speaker system will be muted. You will have to unmute the system manually by selecting volume control if that is the situation.  

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