If you google for 'deaf cat howling' you will find a lot of information on why they do this. He was able to hear about a year ago and when the howling began, I did some research and realized he could not longer hear. You could drop a book onto the floor and not get any reaction.
The sad part is that he's not able to comprehend why this is happening. He's definitely getting to the age where I value the remaining time that we have left. You'd never realize he is almost 84 human years old. He can still mangle my hand when we play, chase down a mouse, but mainly he sleeps a lot.
His favourite game? Sleep...sleep...sleep.
I like to do the hide and seek thing with him. I'll peek at him from behind a wall or door and then disappear. After a few times of doing this he becomes curious and comes to investigate (He does what I call the 'cooing' sound when he is surprised or sees that he is being watched).
At this time I'll go hide and damnit, just like a K9 can find you, so can he. The scent of human must be quite strong to a cat because he can find me everytime.
My old friend grows older and one day will no longer be around... so I like to play with him when I can.