mumbler

the professor was a notorious mumbler, making it hard to follow his lectures.

he's such a mumbler; you have to lean in to hear what he's saying.

despite being a mumbler, he had brilliant ideas about the project.

the witness was a mumbler, which frustrated the lawyer during the trial.

i tried to ask him a question, but he just mumbled something unintelligible.

my little brother is a constant mumbler when he's concentrating on a game.

the mumbler's voice was barely audible above the noise of the crowd.

she politely asked him to speak clearly, as he was a bit of a mumbler.

he's a mumbler, so you really have to pay attention to understand him.

the mumbler's response was so quiet, i had to ask him to repeat himself.

even when he's excited, he tends to be a mumbler.