Mazda 2008 Mazda6 Owner's Manual page 230

Interior Comfort
Audio System
qMute Switch
Press the mute switch ( ) once to mute
audio, press it again to resume audio
output.
NOTE
If the ignition switch is turned to the LOCK
position with the audio muted, the mute will be
canceled.
Therefore, when the engine is restarted, the
audio is not muted. To mute the audio again,
press the mute switch ( ).
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