Similar word to unvocal:

blurred, dumb, faltering, halting, hesitant, hesitating, inaudible, incoherent, incomprehensible, indistinct, maundering, muffled, mumbled, mumbling, mute, obscure, reticent, silent, speechless, stammering, tongue-tied, unclear, unintelligible, unspoken, unuttered, unvocal, unvoiced, vague, voiceless, wordless