Bernie Krause of Wild Sanctuary in Glenn Ellen, California, studies the composition and interplay of sounds in natural soundscapes. He classifies the sounds we hear into geophony (non-living sounds of the Earth produced by wind, water, etc.); biophony (the sounds of life); and anthrophony (the sounds produced by human technology).
He has recorded soundscapes from all over the world and maintains a growing archive of habitat and species-specific acoustic recordings. He has collected and published these sounds in a number of CDs. He is the author of several papers on the niche hypothesis, an argument that in order to be heard, each animal in a soundscape occupies an acoustic niche characterized by a unique combination of frequency, time and timbre.