“Admit a small number of hospital personnel to the band--but not those of great ability. The more varied the instrumentation, the more gratifying the result to the participants.” _Mental deficiency_ means the incomplete development of the mind which makes independent living impossible for the victims. The degrees of deficiency are classified according to the results obtained in intelligence tests: 1. Idiot--mental age of less than three years. 2. Imbecile--age of three to seven. 3. Moron--above the age of eight, but deficient. The treatment for these groups consists of custodial and hygienic care plus any education which can be attained, and of course music will play its part in this in a purely academic manner. SUMMARY Music can be used in psychiatry for its value in listening, group participation, and creation of sound, as follows: 1. _By listening_ A. To improve attention. B. To maintain interest. C. To influence mood (to produce exhilaration, etc.). D. To produce sedation. E. To release energy (by tapping of foot, etc.). 2. _By participation_ (in group singing, bands, etc.) A. To bring about communal co-operation. B. To release energy. C. To arouse interest. 3. _By creation of sound_ (playing of instruments) A. To increase self respect by accomplishment and success. B. To increase personal happiness by ability to please others. C. To release energy. _CHAPTER FIVE_ BACKGROUND MUSIC The average mind is incapable of engaging effectively in two thought processes simultaneously, but it can in the course of daily routine accept a multitude of mental stimuli at any one moment. If one of these stimuli is sound, it may be the natural complement to the visual experience without which a feeling of incompleteness may result. The observer at the sea-side is intrigued by the cyclic rolling of the waves, and the periodic crashing of the breakers is an integral part of the pleasure of watching waves. Yet, that same series of sounds might be very disturbing to the same person who is trying to work out his income tax return in the quiet of his study. The importance of complementary sound becomes more apparent when one studies the reaction of an audience attending the “movies” during periods of faulty mechanical silence. Sound as a background to mental or physiologic processes may be natural or undesirable but can be very important. If carefully selected, there are few situations in which music cannot be used advantageously as a background to improve the quality or pleasure of activities and living. At this point it must be repeated that the importance of music in the lives of people is not uniform and that, for those few who dislike music, background music is not recommended.