The adverse effects of noise, or unwanted sound, have been the subject of extensive research for many years in the fields of psychoacoustics and physiological acoustics. This research grew out of the desire for scientific understanding of these effects on people, especially because of social problems created by the steady increase in the intensity and prevalence of noise found in living and work environments since the start of the industrial revolution. This is the third manuscript prepared by the author on the subject of noise effects. The first, entitled "The Effects of Noise on Man," was a monograph for the Office of Naval Research in 1950 and was published by the American Speech and Hearing Association. The second, of the same title, was sponsored by the Office of Naval Research, the Surgeon General of the Army, and the National Aeronautics and Space Administration, and was published by Academic Press as a book in 1970. The present volume, except for chapter 12, was prepared for the National Aeronautics and Space Administration with support from the U.S. Department of Transportation and from the U.S. Environmental Protection Agency. Chapter 12 was originally prepared for the City of Santa Monica, California. All these manuscripts were intended to be critical reviews and interpretations of the relevant original source literature for the measurement of noise in terms of its effect on people. Except for a relatively few papers, only English language publications were included. In addition to providing major findings of published research, an attempt is made in the present volume to integrate, where possible, the findings into some theoretical framework. In this process, using data from a number of sources, the author undertook analyses and modeling of certain topics. This was done particularly with respect to presbycusis, sociocusis, and nosocusis, damage to hearing, and reactions to community noise. Because of possible interest to researchers in fields beyond "noise effects," has been published in the Journal of the Acoustical Society of America. There has been a particularly significant increase since 1970 in the store of knowledge about noise and its effects, and today many of the seeming conflicts among research findings of the past are found to be more apparent than real. However, the state of the art on certain topics remains best represented by findings published prior to 1970. Although a number of research questions remain, objective methods now exist for measuring noise environments that predict, with considerable accuracy, the effects of noise on people and communities. The first four chapters are concerned with some definitions of terms and research on the fundamentals of noise, hearing, and auditory perception. The last eight chapters are concerned with research on noise effects on more complex human behavior and the application of this research to the regulation of noise in work and living areas.