Welcome!
Please do "About this Mac..." from your Apple menu on the Macbook Pro in question and tell us what that shows for SUB-MODEL including SCREEN size. That affects speaker replacement and, with that info, we can help you with both feasibility and, if required, finding parts. Example of where the sub-model info is located can vary with macOS version):
Also advise if one or both speakers are affected. Some model require different parts for left- and right-side installation.
Apple won't work on a computer that old, so it going to be a do-it-yourself job or you'll need to find an independent repair facility that works on old Macs Also be aware that parts + profesional repalcemte could cost more than a 1-year of Mac notebooks is worth..
As for helping with finding old parts, PLEASE give us a rough idea of where in the world you are (these are international forums), so we don't refer you to a vendor that is 6000km away r does not shipp to your area.
Thanks!