Not quite, everything still makes sounds. Even humans, they just don't have open outlets, so they can only make gutural ones, like moans and grunts.
Yeah I know lol, I said almost silence lol, but yeah the fact that they hear people dying and getting cut up is so disturbing
But that's the thing, it's not almost silence at all, if you think all is missing is human voice.
Cars, sirens, helicopters, running steps, guns, explosions, etc.
I see the image you're picture and it's very disturbing and another more impactful for sure! I hope the anime ignores the literal outcome and makes everything silent like you said it. :D But by logic, yeah, not much.
This is somehow even more terrifying than having speech. Since mouths don't exist anymore, everything is happening in almost silence. No screams, just facial expressions of terror.