Date of Award


Degree Type


Degree Name

Master of Engineering Science


Civil and Environmental Engineering


Dr. Hesham El Naggar


World interest in power generation from renewable resources has been increasing rapidly in recent years. The rapid increase in the number of wind turbines installed worldwide has dramatically increased the number of people living near to large modern wind turbines. Many common concerns raised about wind turbines are related to the noise produced by their operation. Unwanted noise can cause annoyance in people. Various types of noise are generally acknowledged to be subjectively more annoying than others, and some research suggests that wind turbine noise is more annoying than other types of noise, at similar sound levels. One factor proposed to explain this possible increase in annoyance is related to the amplitude modulation which is inherent in wind turbine noise. The principal objective of this thesis is to develop a practical approach to the detection and quantification of amplitude modulation of the noise from wind turbines. The method involves analysis of the signal envelope of individual 1/3 octave band signals, and is described in detail. By comparing the detected rate of modulation to the blade pass frequency derived from turbine operational data, it is shown that the method can successfully detect modulation. Many researches have identified a connection between wind profile and the degree of modulation, but there is controversy in the literature. The precise meteorological conditions leading to elevated degrees of amplitude modulation in wind turbine noise are 111 difficult to define, measure, or predict, but it is generally known or suspected that variation in wind speed over the rotor area (wind shear), and turbulence in the air arriving at the rotor affects amplitude modulation. In this study, the degree of modulation calculated by the method described is compared to wind speed data recorded at various heights, and to the degree of wind shear. Although the correlation is imperfect, the data indicate a connection between amplitude modulation and wind shear.



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