Introduction -- 1. Overview -- 2. Extent of problem ; Changing scope of problem -- 3. Effects of noise. Medical -- Psychological -- Social. Although many of the findings related to noise lend themselves to a variety of interpretations, there is general agreement on a number of factors: 1. Noises of sufficient intensity have caused irreversible hearing damage. 2. Noises have produced physiological changes in humans and animals that in many instances have not resulted in adaptation. 3. The effects of noise are cumulative and, therefore, the levels and durations of noise exposure must be taken into account in any overall evaluation. The recognition of this fact has been translated into legislation specifying limits of total permissible noise exposure in industrial settings. 4. Noises can interfere with speech and other communication. 5. Noise can be a major source of annoyance by disturbing sleep, rest, and relaxation. 6. When community noise levels have reached sufficient intensity, social action has occurred to reduce their effects, This has often taken the form of creating new organizations (or using existing ones) to press for regulation by means of laws, ordinances and standards. - Overview.