Just how much noise do turbines really make?

Taking a look over at the graph on the right, a wind of 13m/s is considered a strong breeze (umbrellas are hard to use at this speed). This model turbine only gives off about 30 Decibels of noise, which if you look at the chart below, you’ll see falls into less noise than a library background noise – so it’s a reasonably quiet device.
Most of the noise you hearing here is also background noise from the wind.  Comparing this to the noise levels we experience every day measured in decibels (DB), distinguishing the noise from the turbine is difficult at best.

31-45 dB is considered a faint  noise zone
This is the decibel level of quiet sounds. In this range, sounds are audible but you may have trouble distinguishing them from other sounds if you are somewhere noisy.  Soft conversation (like what you might hear in a library) falls into the 35 decibel range.

Turbine Blades have become a science
Over the past few years, turbine blades have become a science of their own, with supply companies owning various patents on their designs. The LX range in particular have patented blades that have been designed for maximum efficiency in mind.  Efficiency equals low noise and maximum power delivery to the generator unit.