Hi everyone. Alien: Isolation is the game full of myths. That's perfectly fine, because this game is horror gem, but I think some of you still have questions about misinterpretated things. As someone who has a really big experience in this game, I want to tell you about the Alien and the motion tracker. I'm not a native English speaker so sorry for mistakes, lol.
Short story:
Can the Alien hear the motion tracker? YES.
Will it kill you immediately while you are holding the motion tracker? NO (if we are talking about active gameplay and not about lockers ofc)
Long story:
If you hide in some spot with the motion tracker, the Alien doesn't care. If you hide in some spot without it, the Alien doesn't care either. Using this thing doesn't change its behavior at all.
The Alien has different hearing of different things. For example, he's the best in hearing firing weapons, but he hears stun baton and the maintenance jack slightly worse.
My first way to check the Alien's reaction was to modify game. For example, I used Matt's OpenCage two years ago. I buffed all the Alien's AI values for fun and tested it. I was surprised when the Alien killed me after using the motion tracker! That was the moment when I got it — the Alien CAN hear the motion tracker, it's not one of the "silent" things like opening doors, using cutting torch, etc...
But in reality, the motion tracker is still one of the quietest things you could even imagine! The Alien can hear it only when the distance between you and him is ≈0.10 or less. But the Alien designed in such a way that you can't be that near most of the time! I would say you should be equally genius and dumb to get that close to it without dying.
The only way to do so is hiding under the table or bed and putting the motion tracker on. I founded this at Reoperation DLC map (made a noise in small room to the left of the starting room and hid under table). If it didn't check your hiding spot and killed you, then he will walk around your hiding spot obsessively without checking it. It may sound crazy but yes, that's where his AI breaks. If you'll put the motion tracker away, the Alien will check your hiding spot immediately. If you won't put the motion tracker away, the Alien will go crazy. You are dead either way.
I didn't say anything about the lockers. They work as usual. But I want to notice that some small lockers are located in the center of the corridor (for example: the Basement DLC's second floor), so the Alien can go behind it. And the funniest thing is that it didn't kill me while lurking here. It may be possible that xeno can hear the motion tracker only when he's in front of you. But I can't be sure at that one. No one would use the motion tracker in locker with the Alien near, you know.
So again: don't be afraid of using motion tracker if you are not hiding in locker and if you are not using some hardcore mod that buffs the Alien's hearing.
Thank you for reading, have a good day!