The preferred way of reporting the relationship between annoyance and noise exposure in a community noise situation is by so-called exposure-response functions (ERF). These functions express the percentage of the respondents that are annoyed to a certain degree as a function of the noise exposure levels. ERFs can conveniently be constructed using the CTL method as defined in the standard ISO 1996.Differences between the results from different surveys, or between different sub-groups within the same survey can be expressed as differences in CTL values, expressed in decibels. This difference shows how much more (or less) noise one community will tolerate to express a certain degree of annoyance compared with another community. A high CTL value indicates that the community is very tolerant to noise, whereas a low CTL value indicates the opposite, a low tolerance to noise. The CTL method thus provides a convenient way of quantifying differences between communities.The CTL method was used in the FAMOS project to quantify the effect certain non-acoustic factors on community reactions to road traffic noise.