In the Sydney Airport Health Study, demographic variables (gender, education, and homeownership) were found to influence reaction to noise in areas expecting changes in noise level. Only age was related to noise reaction in steady state low noise areas. These effects of demographic variables may be mediated by the well-recognised reaction modifiers: attitudes to the noise source, and noise sensitivity. Reaction in turn, mediates various negative health effects of noise. We examined whether demographic variables moderate the effect of noise on health outcomes via noise reaction modifiers. Residents in the vicinity of Sydney Airport (N = 1015) were interviewed prior to runway reconfigurations that were expected to increase noise in some low noise areas but not others, and to decrease noise in some high noise areas but not others. Respondents responded to questions about demographic variables and their use of substances (e.g. alcohol, tranquillizers), indicated whether they experienced 9 noise-related symptoms (e.g. headaches, stomach upset), completed the Profile of Mood States, and rated their agreement with statements expressing attitudes to noise. Noise sensitivity was measured by having respondents rate their annoyance with 13 noise situations (e.g. someone rustles papers at the movies). Age was associated with anxiety in all 4 noise change areas, with depression in areas expecting low noise, with symptoms in steady state areas, and with substance use in the high going low noise area. Education level demonstrated associations with anxiety, depression and substance use. Associations of substance use and symptoms with occupation level, home ownership and gender were also observed. There was some evidence for reaction modifiers mediating the effects of demographic variables in the steady state low noise area. The demographic by noise interaction improved the prediction afforded by the demographic variables themselves for noise-related symptoms only. Thus, demographic variables appear to influence the health effects of noise, partly via reaction, particularly in situations where noise changes.