I have a few mattresses lying around in the shed. I think we might have three spare. Maybe one or two big thick rugs as well. Can these be used to soundproof? Even just a little bit?
It should help, cardboard and foam is also a cheap alternative if you're willing to go further.
Yeah I've see it done with egg cartons and rugs. Foam would be good too.
Yeah, but don't let anyone from your local fire department inspection office see it.
Something else came to my mind, I replaced the wooden door in my jam room with a heavy duty metal-ish door a couple of years back and it made a HUGE difference. Just a suggestion if you have some spare cash.