The "hal" prefix in the file name is an internal categorization used by developers, alongside others like "calm," "nuance," and "piano," to help the game engine identify and trigger different styles of background music.
C418 - Subwoofer Lullaby [hal1] | Minecraft — In-game Music Minecraft — In-game Music YouTube• Oct 19, 2020 minecraft_in_game_music_hal1
The in-game music file corresponds to the track "Subwoofer Lullaby" composed by C418 . This piece is featured on the album Minecraft - Volume Alpha and is one of the iconic ambient songs that play during general gameplay. The "hal" prefix in the file name is
You can listen to the full version of Subwoofer Lullaby here: alongside others like "calm