declam

Example:She mumbled her reply so inaudibly that nobody heard her.

Definition:To speak indistinctly or unintelligibly; to murmur

Example:Under the regal seal, he had whispered to his son.

Definition:To speak in a very quiet, low voice

Example:He stammered when he tried to explain himself.

Definition:To speak with hesitations and repetitions of sounds and syllables, as through a momentary defect of intellect or nervousness