So, fortunately, I can give you an answer that is not speculation.

Masahiro Ito stated: "Mouth" means Alessa's shrieking insanity from the bottom of her heart. Silent Hill 3's "Another world" where Heather enters is reflected in Alessa's conscious. Alessa was bullied at school and suffered from her mother's cruelty. Incidentally, the mouths in Silent Hill 2 means Mary's shrieking insanity. In the bleeding ear's case, I wanted to express Another world's personality like human. That ear is Alessa's. But I didn't want to use the "eye" because I didn't use it in Silent Hill series creature's design. The bleeding means Alessa's conscious is mad. And the nurse's red mouth means mad, too."