chunter(speak in a soft, indistinct manner, mutter) verb
lisp [lisped, lisping, lisps](to speak hesitatingly and with a low voice) verb [UK: lɪsp] [US: ˈlɪsp]
whisper [whispered, whispering, whispers](talk in a quiet voice) verb [UK: ˈwɪ.spə(r)] [US: ˈwɪ.spər]Everyone was whispering. = Tutti stavano sussurrando.