General Comments

In the manuscript, the authors conduct an extensive systematic study of wind turbine noise in various terrain scenarios. The computational approach combines the mean velocity from LES with sound propagation using linearized Euler equations. The authors consider no terrain, a wind turbine upwind of a hill, and a wind turbine atop a hill. The analysis is extensive, the conclusions are consistent with prior work, and the authors are careful to make comparisons to similar work in the past. Overall, the authors demonstrate the utility of the linear Euler equations approach. However, there are a few issues that need to be addressed.

Specific Comments

1. The authors use the mean velocity field from LES but do conduct analysis that is inherently unsteady with the single blade sound. What is the influence of using the mean velocity on the single blade analysis? Furthermore, what is the influence of using the mean velocity altogether? Could there be any additional focusing/defocusing of sound due to the unsteady flow field?

2. To assess the influence of the wind speed, which the authors deem to be less important, the LES results are simply scaled. How accurate is this scaling on even the mean velocity profile? For such a strong conclusion, the mean velocity scaling needs to be validated.

3. Only a single hill is considered whose height is the same as the wind turbine rotor diameter and hub height. What is the role of the hill characteristics in the conclusions? Would a smaller/larger hill change the conclusions? Would a less steep hill change the conclusions? These would be very welcome additions to a revised manuscript.

pls see the attached report.