When someone shouts something but they mumble the words.
A loud mumble
When someone is too drunk, dispirited or lazy to pronounce the words but still need to shout in order to be heard
When someone is selling the paper on the street and they shumble the name of it : 'Eeeeiiiiiin hhhzet'(to mean evening gazette)
When being asked from another room if you want a beer etc, replying with a shumble: 'yehhhi'llaahabeer'