It differs from person to person. I've met people who know that they suffer from schizophrenia, some who are unaware, but know hearing voices is abnormal, and some who has no idea.

There's a big difference between the three. The first, the ones who know and care about it - you probably won't even notice he/she is suffering from it, unless they tell you. The others.. yeah.

Source: used to be a med student and a trained hospital sitter.