more adjectives to help define 'fatigue' vectors?

My apologies in advance for posting a naive question, and perhaps erroneously posting this in 'speakers' rather than 'amps' as well, but my efforts to find this answer via search are failing me...

I understand, I believe, what 'fatigue' itself means. But I don't understand in the slightest the causes/mechanisms of it in a listening situation.

I assume there must be myriad causes - but can they be grouped or categorized...and explained in something approaching layman terms?

Fatigue induced by speakers, amps, poor power, etc...do they all have something in common that I'm missing?

Or are they all completely different conditions that result in the same general 'fatigue' outcome?

Perhaps fatigued, perhaps not;
Barry