Lamprophony
This is a clarity of voice at an audible level. So a mumbling, or a heavily salivating jowled, speaker could be described as having a poor lamprophonic quality.
I see this word as one with a lot of potential to cement a place in our current vernacular, as an opportunity for its use presents its self in a quotidian fashion. For instance instead of saying 'sorry, I didn't catch that' or 'could you repeat that' you have an opening to quip 'Your lamprophony is poor could you repeat yourself' or 'You were maundering please increase your lamprophony and try again'.
So I bid you fair serendipity in keeping your communications clear and thus avoiding obfuscating matters.
Ed