The file extension ASND identifies so-called Adobe sound or sound documents. It is a format used only by some Adobe products. Asnd files are not audio files but a kind of container that contains the original audio files of a project as well as the changes, effects and other audio settings. The original files are not changed, which is why this procedure is also called non-destructive.
ASND files are mostly used for editing as well as effect editing audio data before adding to video files. It should be noted that ASND files can only be edited in Soundbooth, all other programs can only process them.