A study consisting of acoustic measurements at fourteen sites in the London area and 1200 interviews dealing with the effects of the noise conditions prevailing at each of these sites has been carried out with the object of developing acceptability criteria for traffic noise from roads in residential areas. Dissatisfaction with the noise conditions, as expressed by residents at each of these sites, was related to sound levels in such a way that it was possible to predict the mediar level of dissatisfaction at each site by the use of a measure taking into account the mean sound levels exceeded for 90 per cent and 10 per cent of the sampling periods through a whole day. Individual dissatisfaction scores correlated poorly with physical measures. This finding is believed to be the result of wide individual differences in susceptibility to and experience of noise, as well as in patterns of living likely to be disturbed by noise. (TC)