My dog is getting on in years and tends not to bark much but on the rare occasions when he does it sounds husky and muffled.
As far as I can tell, he don't seem to be in any discomfort.
How old is your dog Chippy? It doesn't sound as if anything is wrong. As you say, he's getting on and we can all get a bit weaker vocally as we age. I hope he's ok though. Just give him LOADS of love and let us know how he is in a couple of weeks. Keep us informed eh?. I LOVE dogs.
My gsd/collie cross is now 16 and he hasn't barked for about two years now. I put it down to his extreme old age and before he stopped barking for good it was like yours, husky and muffled. I miss his bark, even though he was never much of a barker anyway, but he's still here and is excellent for his age, so I'm grateful for that. Hope this helps.
Chipchopper: I agree with chaptazbru2. I run a dog rescue and we have some dogs that have been with us for years. It's not always about them being old. If they are really really content and are treated very well, you might find that they don't bark anyway.
Not the same I know, but an old animal nevertheless, my cat didn't purr for the last 2/3 years of her life. I think they must keep their energy to just keep on living bless them.