ISP: Monzoon Networks AG
Type of Internet Connection: ADSL2+ Annex M
Internet Connection Speed: 26Mbit/s
Date & Time: 19:30 GMT
Frequency: Sometimes
Character Name: Reih Falon
Race: Miqo'te
World: Ragnarok
Class/Level: Any
Area and Coordinates: Overall
Party or Solo:Solo, in Party, in Instances
In-Game Time: Server Time: 9:30 PM

Steps:
This happens every time I play for longer times. I sometimes leave the game on to play on the remote play feature for PS Vita. When I return to the playstation version of the game the sound is all messed up. It may play a bgm or it may not. Try leaving a PS4 run the game for several hours until the sound is gone.

Only way to solve this is closing the app and restart the app.