your computer presentation includes sound and you did not connect
it to the projector's DisplayPort or HDMI
port, you can still play sound through the
projector's speaker system (PowerLite Pro
. Just connect an
optional 3.5 mm stereo mini-jack audio cable as described here.
Note: If your
projector does not have an internal speaker system (PowerLite Pro
G6800/G6900WU), you can play sound by connecting external speakers
to the projector.