The effect of sound duration on annoyance

The purpose of this study is the investigation of the dependence of the duration effect on the level of noise and/or the duration itself, as well as the measurement of the duration effect expressed as a trading relation between the level and the duration. The stimulus was white noise whose duration ranged from 30 ms to 90 s for each of four levels of noise. Ten male and ten female subjects judged the annoyance of those sounds by means of the method of magnitude estimation. Results indicate that the annoyance increases in linear proportion to the duration up to 90 s in log-log co-ordinates. The slope of the duration effect is dependent on the level of sound and the result is most appropriately expressed by a multiple regression equation which contains an interaction term between the peak level and the duration. Contours for equal annoyance are drawn from the equation and the curves appear to show that the slope of the duration effect is dependent on the duration. This proves to be so, however, because of the dependence of the duration effect on the level of noise. If the interaction term between the peak level and the duration in the above equation is neglected, then the average slope of the duration effect can be obtained as 3·4 dB per doubling of the duration.