I wonder if that people that beat it without mic are full of bullshit or it's true. I never could myself, that's for sure.
The point is, the real solution (as per PSblog hints) is that you need to use a mic, and call for Jack (saying his name) for one laugh.
https://blog.eu.playstation.com/2014/10/31/p-t-ps4-survival-tips-konamis-horror-hit/
The random demonic voices can be hints, but they're reversed in-game so they¡re really hard to understand.
Also, Lisa can do kill you on the last part, when she rush towards you she starts following you behind you, and can randomly kill you. Thing is, is totally random when, so she can kill you 10 secs after or never... it triggers when turning around, but still it's random.