Synonyms and related words :
aspiration, bated breath, breath, breathy voice, drone, droning, exhalation, gabble, gibber, gibbering, jabber, jibber, little voice, low voice, maundering, mouthing, mumble, mumbling, murmur, murmuration, murmuring, mutter, muttering, rumor, sigh, soft voice, stage whisper, still small voice, susurrus, underbreath, undertone, whisper, whispering