サウンドプレイヤー (Sound Player) is an original song produced by tilt-six with vocals by バル (Baru), first introduced to the rhythm game scene via CHUNITHM AIR in December 2016. The track joined the maimai song library nearly nine years later as part of maimai でらっくす PRiSM PLUS on July 11, 2025, continuing the long-running content collaboration between Sega's maimai, CHUNITHM, and ONGEKI franchises. tilt-six, a composer known for vocaloid-driven electronic pop and contributions to the BMS (Be-Music Source) doujin scene, handles composition, arrangement, and lyrics. The song's upbeat tempo and energetic vocal delivery revolve around a central theme of musical compulsion, the narrator describes themselves as a "sound player" who cannot stop dancing and playing music, caring little for the gaze of others. In maimai, the track features DX-only charts across all four standard difficulties. The Expert chart (level 10) was designed by 鳩ホルダー (Hato holder), while the Master chart (level 13+, constant 13.7) was designed by サファ太 (Safata), the latter packing 837 total notes with a particularly dense concentration of Touch notes (107) and Break notes (33), making it a technical challenge within its level bracket.