Doing a commercial 70volt dist audio system. One tech told me I need to ground the shielded speaker cable with the emt while another told me that I didn't need to. So who's right?

I'm running the 18-2 inside the same conduit as my coax+power for the 24ac cameras, so I decided to use twisted pair shielded speaker cable that comes with a drain wire and 100% aluminum foil.