Affective response to amplitude modulated wind turbine noise

Residents living adjacent to wind farms are exposed to a combination of turbine noise and background noise with all its environmental and local constituents. As the amplitude modulation character in turbine sounds is thought to specifically contribute to the annoyance response listening tests were conducted in a controlled laboratory environment with the aim to find annoyance ratings as a response to modulated wind turbine sounds. The stimuli were 20 s noise samples systematically changing in LAeq level and estimated modulation depth. They were presented to 20 participants in random order. The participants rated the annoyance of the noise samples on an absolute scale and adjusted an unmodulated reference sound in volume to be equally annoying as the noise samples. In agreement with a previous study by Lee et al. (2011) annoyance rating trends are shown to increase significantly with sound level and not statistically significantly with modulation depth. A clear on-set of annoyance at a modulation depth threshold was not observed. The results are interpreted in the context of the study limitations and comparisons between the LAeq and LA90 metric are drawn