This archive contains a few seconds of absolute silence encoded as MP3.
As you can see the archive is only 1k but it expands to a fair size suggesting
that MP3 doesn't compress, it just represents the sound in a different way.

 PERMSSN    UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 1004  213450   0.5% -lh5- 0c78 Feb  6  1998 test.aiff.mp3
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         1 file     1004  213450   0.5%            Feb 14  1998