struck dumb

hushed mum mute restrained reticent

bashful buttoned-up checked clammed up close closed-up closemouthed curbed dumb dummied up faint hush iced inarticulate incoherent inconversable indistinct inhibited laconic mousy muted noiseless nonvocal not talkative reserved shy silentious soundless still taciturn tongue-tied unclear uncommunicative unheard unsociable unspeaking voiceless wordless zipped

clamorous communicative explicit noisy talkative tangible