There are so many things this could be.

In the pub, is there background noise? Not just conversation and TV's, but fans, air conditioning, fridges humming, central heating blowing? As people get older, it gets harder and harder to hear voices against such noises.

If your lungs are okay, it is doubtful that you are fading away. Why don't you try some voice lessons and beef up your always-quiet voice.

Don't believe that 'singing is shouting in tune.' That's not true. Shouting could ruin your voice.