Hi,
Here is a link to the [http://h20628.www2.hp.com/km-ext/kmcsdirect/emr_na-c03943612-2.pdf|service manual] for your laptop.
Scroll to p.95 to view the necessary pre-requisite steps and thenthe procedure to remove the speaker assembly.
Also on p.95 you'll find the HP spare part number for the assembly (730798-0010).
Search online using the part number ''only'' in the search box of your browser, to find suppliers of the part.
Hopefully this is of some help.