Wind Turbine Noise
Do wind turbines make noise?
Yes, wind turbines generate two types of noise: aerodynamic noise and mechanical noise.
The aerodynamic noise is generated from the blades as they pass through the air. The loudness of the aerodynamic noise is related to how fast the tip of the blades are spinning, the size of the blades, and the wind speed. The greater the wind speed, the faster the blades spin, and the louder the aerodynamic noise will sound. The aerodynamic noise of a wind turbine is usually described as a whooshing, buzzing, or pulsating sound.
Mechanical wind turbine noise is generated from the inner working components and rotating gears of a wind turbine. More expensive, utility size wind turbines are usually very well insulated to prevent any mechanical noise from leaving the nacelle or wind tower. Smaller, more economy size wind turbines may be less insulated which will sometimes result in more noticeable mechanical noise outside of the wind turbine.
Are these noises loud enough to be a disturbance?
The amount of disturbance that wind turbine noise will likely cause can be closely related to other ambient noises in the area. Depending on the surroundings of the wind turbine, often times other noises like nearby traffic, ocean waves, or other natural ambient noises will mask any noise produced by the wind turbine. At low wind speeds and without other noise production nearby, the noise from a wind turbine is more noticeable, but at higher wind speeds, the noise from the wind can easily be loud enough to mask any noise from a wind turbine.
Perhaps the most important measurement of wind turbine noise is if it is more than 5dB louder than any background or surrounding ambient noise. If a wind turbine starts to bypass the 5dB level of loudness over surrounding ambient noises it will start to become noticeable. More than 10dB above, it is more noticeable and may begin to cause an annoyance. More than 15 dB above and it could be very irritating.
It is important to remember here that ambient noises change at different times of the day, usually being lower a nighttime, and depend on the surrounding natural environment and the habits of the local inhabitants. If, for example, the surrounding livable area was occupied by people who made little noise and valued peace and quiet, then the noise from a wind turbine could be a disturbance at lover decibel levels. But if the surrounding areas were occupied by farmers or other workers who frequently used loud machinery, then the wind turbine noise would have to reach a much higher decibel lever to be louder than the surrounding ambient noises and become a disturbance.
Can Wind Turbine Noise cause a psychological disturbance?
There have been cases of the aerodynamic “whooshing” noise of a wind turbine causing psychological stress, loss of sleep, fatigue, and emotional stress. The “whooshing” noise, which is usually easier to hear at night due to lower ambient noise levels, is a pulsating noise that occurs simultaneously with the spinning of the blades. The faster the blades are spinning, the more frequent the pulse of the sound becomes.
Without other ambient noise to block out this whooshing noise, there have been many cases of nearby residents being very irritated by the wind turbine. There have also been a few cases of people going “crazy” from the constant pulsating whooshing noise of a nearby wind turbine.
Conclusion
The amount of potential noise disturbance of a wind turbine is subjective, with a huge factor being the decibel level of nearby ambient noise. The amount of irritation caused by wind turbine noise is decided by the beholder. There also, however, may be an incalculable disturbance from the “whooshing” sound, or the low-frequency infrasound noise levels produced by a wind turbine that can cause psychological stress.