If you are looking to add another cable outlet or are hanging content on the walls and don't want to strike anything beyond the drywall, it is a good idea to determine if cable wires are installed in walls around your home. You can use several detection methods to check the locations of the cable wires without actually ripping out the wall to see if the cables are there.
Check to determine the types of rooms found on either side of the wall in question. A kitchen or a bathroom will likely feature heavy electrical cables and plumbing; however, cable wires probably aren't present.
Walk outside if the wall is facing out. Look at the location where the wall meets the roof and see if anything is sticking out of the roof. You may find cable wiring around the connection. If you see this, a good chance exists that cable wires are located on the opposite side of the wall.
Look at the rooms directly above the wall you are inspecting. If any of the rooms above the wall in question have a cable outlet, the cable more than likely extends straight down into the wall you are checking.
Check for electrical sockets. Oftentimes cables are fed through the same openings made for electrical wiring. If the wall has a power outlet, the cable wiring may also be in the same area.