Schizophrenia is classified with two types of symptoms. Since it is classified as a psychotic illness you do need to experience psychotic symptoms to be diagnosed with it. The two types of symptoms are refereed to as "positive" and negative symptoms. They refer to hallucinations as "positive". That includes voices and visual hallucinations (as well as other senses). Delusions and other similar symptoms are classified as negative symptoms. There are plenty of schizophrenics who don't experience the "positive" symptoms that often . Refer to the DSM-IV TR or DSM-V for more information. (as well as members with schizophrenia).

Please note: A grand misconception of the public is ANY psychotic symptom means you have Schizophrenia. This couldn't be further from the truth. My own mother believes my uncle is Schizophrenic. This is untrue. Also another misconception is "Multiple Personality Disorder" is the same as Schizophrenia. "Multiple Personality Disorder" has been removed from the DSM, and has nothing to do with Schizophrenia.