One thing that's always bugged me are the hearing aids Shouko wears at the beginning.
We're never specifically told just how bad her hearing loss is, but it is heavily implied that if it isn't complete it's very close to 100%.
So what would the point of giving hearing aids to a completely deaf person. Way I see it, hearing aids are only useful to people with partial hearing disability. Shouko seems completely deaf so they would be pretty useless on her. Are they merely a covenient plot device to illustrate the bullying she goes through?