Noise sensitivity or something else?

Hi all, 

Got to say that even after almost a year, I'm finding understanding my triggers that are so contradictory almost impossible. 

Today I've had to come home sick from sensory overload because of some heavy hammering being done behind me with no warning. 

There's plenty of evidence that I struggle with sensory issues.   However there's also contradictions.  Give me a hammer and I'll happily hit things on occasion. 

Is there some subtlety around sensory overload around lack of anticipation that makes the difference? 

Do other autistic people find their sensory issues simpler, whether they're creating the noise or not? 

Thanks, 

Craig