1. The hint mentioned [Audacity](https://installati.one/install-audacity-kalilinux/), so use it to open the file.

2. Use a [morse code decoder](http://www.unit-conversion.info/texttools/morse-code/) to decode it (Type in `-` for long long lines, `.` for short ones)

3. Then put underscores in place of pauses
=>`wh47_h47h_90d_w20u9h7`
<hr>
REF: https://www.youtube.com/watch?v=Tqxqh2hej9o
(but it's not much related, since the flag file is prettty clear compared to the audio file in the video)