Acoustics, the study of sound, is a fairly well-established discipline, full of descriptions of air particle movements and so on. I won't go into that much detail, mostly because I'm not qualified to. But some understanding of basic principles is needed to fully appreciate how noise regulations are structured, and where their weaknesses might be.

The following sections go into more details on the topics that seem to pertain the most to wind turbines.

• All About Decibels
• How Sound Spreads
• Frequency Weighting
• Averaging Noise