Mumbling covers a lot of sins. When you're abashed or ill-prepared or simply your usual fifteen minutes away from l'esprit d'escalier, mumbling could be the way to go. Broca's area has lost contact with ground control, yet utterance is obligatory: dive! dive! dive! And from somewhere deep in the reptilian part of your think gel come noises that sound so close to speech that some of the people some of the time can be fooled.
Lawyers don't get to mumble much, though. For one thing, it doesn't work very well in print (which is not to say it's impossible) . . . [more]