If the change in hearing is new or seems sudden, tell your vet. Older dogs can have several changes at once, including vision or pain issues, so don't assume every missed cue is simply stubbornness or age. Ask about their comfort if they flinch when handled.
Start where your dog can see you
Move into their line of sight before reaching toward them. Let them notice you, then offer an easy hand signal and a reward. A clear thumbs-up can become your version of 'yes': show it, give a treat, and repeat in short, comfortable sessions. Once your dog expects a treat after the signal, use it to mark a small behavior they already enjoy doing. Keep the signal consistent across everyone in the home.
If your dog also has trouble seeing, a visual cue may not be enough. Ask your vet or a qualified reward-based trainer to help choose a safe way to get their attention. Don't use an unexpected tap on a sleeping dog or assume a vibration collar will be gentle, some dogs find vibration frightening. Outside, keep safety in your hands with a secure leash or fenced space rather than relying on a cue your dog may not perceive.
Tonight, wait until your dog is awake and looking at you. Give one easy thumbs-up, then a treat. Repeat a few times and stop before they tire. You have begun a shared language again, there is no need to teach a whole routine in one evening. After checking a new hearing change with your vet, see the senior dog changes guide for more on adapting communication and daily life
Sources: Dogs Trust on living with a deaf or blind dog. VCA on training a deaf dog.