In this laboratory study of annoyance due to traffic noise, the equivalent sound levelLeqwas found to correlate more highly with subject's annoyance measured on a subjective scale than a number of other noise descriptors and subject variables. Although regression analysis showed that a number of other variables was also statistically significant (among them subject's sex, number of truck gear changes, standard deviation of the sound level, and subject's sensitivity to noise), these were not thought to add appreciably to the variance explained byLeqwhen the complexity of considering them in real life is considered. The experiment therefore confirms the use ofLeqas a single, governing variable in determining the annoyance due to traffic noise.