Npc eye

How I can get to know about am i seen by npc.combine or not, by his code?

Translation: How do I know if an npc_combine can see me or not?

Generally if you are behind him the NPC cannot see you. But if you move behind a NPC it “hears” you and turns around to the source of the noise (Same with bullet impacts). I tried once and they wont hear you if you walk with alt.