What is an AU File?
An AU file stores audio content in 3 parts; a header, an annotation block, and the actual audio data. .AU Files are mostly used on Sun or other Unix-based operating systems and have gained popularity that some audio programs have also incorporated support for .AU files natively.
The .AU file type is not to be confused with the AU files used with Audacity software, where any audio file imported by the program is automatically converted into Audacity’s proprietary format.
Download AU Sample Files
From here you can download .AU sample files to test out that are available in different file sizes and audio lengths.