The Relaxation Company may disagree, but the gurgling of mountain brooks (''Yosemite National Park'') can easily be mistaken for the drizzle in the rain forest (''Olympic Rainforests'') or the lapping waves along the Massachusetts coast (''Cape Cod Seashore''). Despite this lack of aural distinctiveness, David & Steve Gordon's Sounds of America: Musical Portraits of Natural Wonders is genuinely soothing and often quite lovely. B

