But natural sound is not merely a profession for Krause. Aural wonders are Krause's obsession, and he has become a veritable missionary of naturalism and sound. He equates the loss of a vibrant soundscape with the loss of a natural habitat, and he says that nowadays he has to record about 2,000 hours to produce one hour of usable sound; when he first started three decades ago, it only took 15. And, he adds indignantly, 25 percent of the habitat in his audio library no longer exists because of environmental degradation by humans.