All I know is that I was stuck for an hour and half on the last loop the night it released.
Tried to connect the noise types with locations, and by facing them I finished the game in more or less 15min. Took less than 2 minutes to get the phone to ring.
I don't know if it doesn't work if you get attacked (I managed to complete it without getting jumped, even though I wasn't avoiding it) but it works. For every kind of sound she has like 2 random different places to appear. I stuck to only checking 3: radio, phone, sink.
After 10 steps, giggle. Moved to bathroom (expecting she would spawn there so it would save me the trouble of moving towards her). Talked to baby. Second haunting triggered faster than normal. Static noises and beeping, Radio. Went there and it stopped. Then returned to the bathroom, as that is the place of my choosing to be idle in between hauntings. Talked some more, next haunting had the same static and beeping, knew it was from the radio. Didn't bother to look for her, I just went for the object associated with the noise. Stood there till it stopped, back to bathroom. Talked to the baby and as soon as I stopped saying like "helloooo" I got the final giggle. EDIT: Second giggle, sorry. The third is just staying put after the second, so no harm done.
Yes, it's random and she can appear in 6 locations. But she only makes 3 types of noises. Identify which is it, and move towards the corresponding object. Maybe the differentiating factor here was that I *wasn't* attacked/possessed and that I always chose the bathroom to wait in between hauntings. The mic seemed vital. I picked up my first save on the american account I have, where I was stuck for 1h30m, did all this and got the ending in 5 minutes flat.
It works, and in that save I had been attacked, had different colored flashlight and everything.
Her photograph pretty much spells it out, but in the beginning everything seems so random that we don't take it seriously.
"My voice, can you hear it? This sign, can you read it? I'll wait forever if you'll just come to me." Just distinguish between noise types, the one on the background (as I've had the exact same crying, one with beeping and static and the other without) and move towards one of the 3 important objects. This shit works everytime for me.