It seems like the current AI scripting has them beeline for the source of a sound in the highest aggression possible, without any timeouts or anything. They *will* get to that location. Only then do they lose their laser focus and start bumbling around like mindless undead again.
It would be nice if they ratchet up. The first noise has them wander less-aimlessly towards the noise, but be ok with going off on a tangent and lose interest quickly. Only if they hear continued noise do they aggro up to manic breaking, and it ought to take a few iterations of noise to get that focused.
I've had things go 20+ blocks, up, around and through, over a single small noise. There isn't any of the movie-like "move close, shuffle and snuffle, sense nothing else and shamble away" that makes cowering silently in the dark worth doing. You activate anything now, you HAVE to run far or kill it. No cowering allowed.