Machine giving up the ghost?

Not sure if this question has ever been asked, but here it goes.
How can I tell if my machine is about to die? Does it make sounds or does it just crash?
I ask because my machine was "singing" last night - variation of medium to high pitch tones.
It is about 5 years old.
Any input would be great. Thanks.

Most of us here plan ahead, and have one or more XPAP machines as well as any necessary items to replace damaged items, not hoarding just being ready for life in the real world.

I'd take your post as a warning Murphy was in your area, and he or his friends were coming to visit you. Jim