slience your whumpees
two cruel ways you could do this
non/semi permanet:
make them forget how to speak, idrc how you do this but imagine how helpless they will feel once they cannot do something so mundane and normal anymore that they've been doing all they life and they can only make noises and will have to relearn how to speak again which might make them feel like a child and will hate it.
punish them into slience and a fear of speaking or making noise, hit them, burn them do whatever cruel and harsh thing you want to do everytime the whumpee speaks or even whimpers or gasps, until they become so scared to speak or make noise they don't even try and if there ever rescued this fear lingers, and they have to learn that they can speak freely without pain
3. sew your whumpees mouth shut, with wire or thread, make it so they can't even open their mouth, they won't be able to speak, scream and might *might* barely be able to whimper if there lucky, this would mean they cannot eat or drink as well, and if you want faux sweetness let the whumpee pick what color thread or what kind of wire, bouns points if after its cut out there ridges and scars on whumpees lips.
permanet ones!:
cut your whumpees f*cking tounge out of their mouth, this might make them not be able to speak or it will ruin their speach so much theres no way of speaking. if you want to be morbid you could put the tounge in a jar infront of whumpee and make that the only thing to look at in their cell or make them eat their own tounge.
2. this one is inspired from the webcomic/webtoon Slient Screams by Glamist (please read it), remove your whumpees vocal cords... this would mean no matter what they cannot produce a sound let alone speak or scream, even if they escape they won't be able to speak because their "voice box" was removed, they would have to learn how to sign (if there hands are not broken or missing a finger) or only be able to write notes or type out what they want to say imagine the helplessness
