Go under the "Audio Input" page and under the "transmit" menu, choose Push to Talk
3.
Go to the "Shortcuts" page. Click "Add" at the bottom, then for "Function" choose "push to talk". For "Shortcut" just set your desired key. Hit "Apply" and "Ok" on the bottom right.
Congrats! Whenever you push the key you set as your shortcut, your voice will transfer over Mumble. Whenever you depress the key, your voice won't transmit.
In OSX
1.
Under "Mumble" in the upper left, choose "Preferences"
2.
Under the "Audio Input" page, go to the "Transmit" menu and choose "Push to Talk"
3.
Go to the "Shortcuts" page. Click "Add" at the bottom, then for "Function" choose "push to talk". For "Shortcut" just set your desired key. Hit "Apply" and "Ok" on the bottom right.
Congrats! Whenever you push the key you set as your shortcut, your voice will transfer over Mumble. Whenever you depress the key, your voice won't transmit.