Events in the Landscape and their Acoustic Shadows

While writing the previous post, about sound and warfare in Iraq, I came across a brief description of something called an acoustic shadow and its occurrence during the American Civil War.
An "acoustic shadow" is when the sounds of an event—here, a battle—cannot be heard by people nearby—say, in the neighboring valley or a parallel city street—but those same sounds can plainly be heard over much larger distances. This effect is caused by "a unique combination of factors such as wind, weather, temperature, land topography, forest or other vegetation, and elevation," we read. For example, "battle sounds from Gettysburg fought on July 1, 2, and 3, 1863 could be heard over one hundred miles away in Pittsburgh, but were not heard only ten miles from the battlefield."

BLDGBLOG