To measure reactions of people to levels of aircraft noise in residential areas. Variables Both social surveys and physical aircraft noise measurement programmes were carried out. The social surveys measured the effects of the aircraft noise on people's lives and characteristics of people which might have an influence on people's reactions to aircraft noise. Data on reactions were collected from three groups of cities. Somewhat different questionnaires were used for each of the groups of cities. The physical aircraft noise measurement data were used to determine the noise level at each respondent's residence.