Sun/NeXT/DEC/UNIX sound file
AU files contain three parts: the audio data and text for a header (containing 24 bytes) and an annotation block.
MIME type: audio/basic, audio/x-basic, audio/au, audio/x-au, audio/x-pn-au, audio/rmf, audio/x-rmf, audio/x-ulaw, audio/vnd.qcelp, audio/x-gsm, audio/snd
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