Trying not to murder my in laws and may fail

Me: Could you guys just be a little quieter when you’re upstairs since we just got the baby to sleep?

Them: wHy, CaN hE oNLy sLEeP iN tOtAL siLeNcE? He NEeDs tO gEt uSEd to nOiSe

Me: no, he’s just a human with ears and you’re literally yelling to each other right outside his door.

I just feel like this response is so disrespectful to my sleep and sanity - they wouldn’t tell and make noise if an adult were sleeping, so why do it when it’s my baby? I’m trying to just go with the flow but it’s really hard.