The Noise-Reduction Manual was prepared under the auspices of the U.S. Office of Naval Research and was originally intended to constitute the introductory sections of a more extensive study of noise-reduction problems encountered aboard ship. There is a sustained emphasis on the practical techniques for the reduction of airborne noise, the treatment of each problem tacitly deprecating the need for, and even the practical value of, mathematical investigation of noise sources and noise fields as compared to the greater importance of careful acoustical measurements designed to direct the proper use of acoustical materials and relatively simple noise-reduction techniques. Careful distinction is made between the various techniques of noise reduction at the source and the various methods of noise and vibration isolation and dissipation, greatest emphasis being devoted to the latter. After basic definitions and analysis of several causes of noise, entire chapters are devoted to absorption of airborne sound, insulation against airborne sound, vibration damping, and vibration isolation. Each chapter contains extensive discussions of the evaluation and application of the various types of acoustical materials, including selection rules, performance data, and instrumentation. The straightforward exposition should make the manual equally valuable to both the novice and expert in the field of noise reduction.