Auditory hallucinations are the most frequent and characteristic
symptoms in patients with schizophrenia, and are
often described as ‘‘voices’’ [30,37]. Epidemiological studies
have suggested that auditory hallucinations have occurred at a
prevalence of 10–39% in populations without neuro-psychiatric
illness [1,39], and 60–75% in patients with schizophrenia
[12,30]. Auditory hallucination is often treated with antipsychotic
medication; however, this symptom may persist in
approximately 10–30% of patients despite adequate medication
[19,37], in which case the auditory hallucination becomes
‘‘persistent auditory hallucinations’’ [3].