I find that it's easier to tune out something that is totally periodic and unvarying. As annoying as a smoke detector chirp would be, your brain knows with cert

I find that it's easier to tune out something that is totally periodic and unvarying. As annoying as a smoke detector chirp would be, your brain knows with certainty the timing and sound of it and can process it out completely. A noise that is generally around, but comes and goes and varies in pitch and volume without predictability, can be much more annoying.