We studied 25 clinical characteristics of auditory hallucinations by means of 3-point observer-rated scales in a sample of 60 inpatients with mainly schizophrenic or schizophreniform disorders. The interrater reliability of the scales was found to be satisfactory. High levels of conviction about the reality of the sensory stimuli, clarity of content, location of their source of origin and lack of volitional control were found to be the hallmarks of verbal hallucinations. This finding supports the hypothesis that the concept of auditory hallucinations represents many aspects of patients' hallucinatory experiences, which are relatively independent of one another.