-
A 64GB sound file would be a bit hefty
Doesn't have to be one file, or any particular type of file. I used to have a set of junk files sized in powers of two for testing, so you could assemble arbitrarily sized groups of files by bundling them together. Anything much over 100MB it's easier to find video files of a suitable size. If you want to be thorough, you need files down to the block size of the disc to ensure that you can keeping adding files until the free space is nominally zero, i.e. all blocks have been overwritten with junk.
A 64GB sound file would be a bit hefty (guess I could find a smaller drive).
It's a work laptop so no admin rights (on the flip side it means I wouldn't personally be sued).