When qt-dbus is installed on your system you can control Mumble through dbus.

• Self mute
• Self unmute
• Self deafen
• Self undeafen

mumble-mute () 
{ 
    qdbus net.sourceforge.mumble.mumble / setSelfMuted true
}
mumble-unmute () 
{ 
    qdbus net.sourceforge.mumble.mumble / setSelfMuted false
}
mumble-deaf () 
{ 
    qdbus net.sourceforge.mumble.mumble / setSelfDeaf true
}
mumble-undeaf () 
{ 
    qdbus net.sourceforge.mumble.mumble / setSelfDeaf false
}

qdbus net.sourceforge.mumble.mumble /

If you start Mumble mehrfach gestartet multiple times then you can only control the first instance.

Since Mumble 1.3.0 you can use a better method, see here.