THIS DISCUSSION OF THE BASIC FUNCTION OF ACOUSTICAL MATERIALS--THE CONTROL OF SOUND BY SOUND ABSORPTION--IS BASED ON THE WAVE AND ENERGY PROPERTIES OF SOUND. IT IS STATED THAT, IN GENERAL, A MUCH LARGER VOLUME OF ACOUSTICAL MATERIALS IS NEEDED TO REMOVE DISTRACTING NOISE FROM CLASSROOMS AND OFFICES, FOR EXAMPLE, THAN FROM AUDITORIUMS, WHERE A CERTAIN AMOUNT OF REVERBERATION AND SOUND REFLECTION IS BENEFICIAL. IMPORTANT PROPERTIES OF MATERIALS SUCH AS MAINTAINABILITY, FLAME SPREAD, AND FIRE RESISTANCE ARE DISCUSSED, AS WELL AS PROCEDURES FOR REDUCING SOUND TRANSMISSION FROM OUTSIDE SOURCES. APPENDICES INCLUDE DEFINITIONS OF SCIENTIFIC TERMS, CHARTS, AND SOUND ABSORPTION COEFFICIENTS OF BUILDING MATERIALS AND FURNISHINGS. THIS DOCUMENT IS AVAILABLE FOR $0.50 FROM ACOUSTICAL MATERIALS ASSOCIATION, 335 EAST 45 ST., NEW YORK, N.Y. 10017. (JO)