AST files contain PCM16 sound data. They're used in Super Mario Galaxy for musics, and possibly in other games.
They contain an header followed by a BLCK chunk. All the data in those files are big-endian, except where mentioned. All the offsets are absolute (from begining of file), except where mentioned. All the sizes are in bytes, except where mentioned.
The header is 64 bytes long.
|0x0004||4||Size of the BLCK chunk|
|0x0010||4||Sampling rate in Hz|