Sound Oasis Sound Cards are the world's first memory cards that allow Sound Oasis owners to expand their collection of available sounds. By simply inserting the patent pending sound card into a conveniently located slot on top of the Sound Oasis, users can supplement their unit's built'in sound offerings with 12 additional digitally recorded sounds. Thunderstorm, crashing waves, forest rain, waterfall, gentle surf, ocean rain, wind, secluded lake, caribbean surf, jungle stream, summer night & amazon lagoon.