This got me thinking of a project where I had to choose a notification sound for an alarm feature: something that required the operator’s attention but didn’t need them to take drastic and immediate action. I went for a tone that was pleasant to hear at first, but got annoying the more often you heard it. The theory I had at the time was that this would elicit an emotional reaction in the operator (in this case, annoyance) to cause them to take notice; but only for a moment, just enough for them to at least look at the alarm panel. This was not based on any science so I don’t know how effective it was, but it seemed to work on me.