1. The demonstration of increase of muscle potential of the vocal organs in a case of schizophrenia experiencing verbal hallucinations suggested further investigation. Accordingly, electromyograms of the vocal musculature were obtained from 100 patients and 100 normal controls by means of an electroencephalograph machine.2. Forty of a group of 48 patients experiencing verbal hallucinations (83%) had increased potential. Of a combined group of 64 having or probably having auditory hallucinations, 53 (82%) had increased potential.3. Of the group of 33 patients not experiencing hallucinations, 30 (90%) had no increase of muscle potential. Of the combined group of 36 not experiencing or probably not experiencing hallucinations, 31 (86%) showed no increase of muscle potential.4. In the group of 56 schizophrenic patients who were hallucinating or probably hallucinating, 45 (85%) had an increase of muscle potential.5. Tension in the "throat" exists in 28% of a sampling of the normal population, whereas it is present in 58% of a sampling of patients in a mental hospital.6. Hyperactivity of vocal musculature in the psychotic appears related to the presence of verbal hallucinations.7. The electromyogram of the vocal musculature offers a laboratory method for determination of presence of verbal hallucinations and for the graphic portrayal of change of tension following treatment.8. A theory of verbal hallucinations is tentatively reaffirmed concerning involuntary intensification of the psychomotor mechanism of speech.9. A study of muscle tension patterns by means of simultaneous electromyograms is suggested.Abstract Teaser