Mercedes-Benz GLS Operator's Manual page 363

Switching the sound on/off
On the multifunction steering wheel
On the multimedia system
To mute: press volume control 1.
#
The current audio source is switched off.
The 8 symbol appears in the status line
of the media display.
If you are listening to a radio station, for
example, and switch off the sound then all
media sources will be muted.
MBUX multimedia system 361
Traffic and navigation announcements can
still be heard in this case. Likewise, voice
control and telephony are not affected.
To switch on: turn volume control
#
change the media source.
1 or