The aural richness of a habitat is a direct measure of its biodiversity. Comparing this before and after any human impact on a landscape, we can get an indication of how much biodiversity has been lost.
Bernie Krause has been recording wild soundscapes -- the wind in the trees, the chirping of birds, the subtle sounds of insect larvae -- for 45 years. In that time, he has seen many environments radically altered by humans, sometimes even by practices thought to be environmentally safe. A surprising look at what we can learn through nature's symphonies, from the grunting of a sea anemone to the sad calls of a beaver in mourning.