Naturalist and sound recordist Dr. Bernie Krause first surfaced during the early 1960s as Pete Seeger's replacement in the legendary folk group the Weavers; by the middle of the decade he was working as a staff producer at Elektra Records, in 1968 teaming with jazz musician Paul Beaver to record the LP The Nonesuch Guide to Electronic Music, a groundbreaking excursion into experimental sounds and textures which made innovative use of early synthesizers. The duo of Beaver & Krause went on to record a series of electronic records before the former suffered a fatal heart attack in early 1975; in the wake of his partner's death, Krause turned to presiding over his company Wild Sanctuary, Inc., an organization devoted to, among other subjects, terrestrial and marine bio-acoustic recording and analysis. In 1979, he also issued his debut solo album, Citadels of Mystery. Krause spent the early 1980s studying the science of bio-acoustics everywhere from Alaska to Kenya, recording environmental sounds from all corners of the globe; in 1985, he earned international attention when his recordings of humpback whale sounds proved successful in luring a lost whale named Humphrey from out of the Sacramento River Delta back to the Pacific Ocean. Bernie Krause also helped develop the Intelligent Sound System, described as "an automated system for public exhibitions and installations that creates non-redundant audio recreations of the natural environment; " he additionally released dozens of environmental recordings spanning from Sounds of a Summer's Evening to Amazon Days, Amazon Nights to Ocean Wonders. ~ Jason Ankeny, All Music Guide