The item changes the background music to chiptune-like rearrangements of the tracks in the area that are similar to the original ones from Pokémon Gold, Silver, and Crystal. Sound effects and radio music are unaffected by the GB Sounds.
Despite the fact that the old-style tracks are supposed to sound like the original tracks from Pokémon Gold, Silver, and Crystal, none of them sound exactly like the originals. This is due to the way chiptunes are handled on the Nintendo DS. The capabilities of the PSG found in the DS line is limited compared to the one found in the Game Boy line. The DS PSG has fixed square wave and noise channels like the Game Boy PSG, but lacks the crucial 4-bit wavetable synthesis channel, which renders the DS incapable of generating the variety of different waveforms the Game Boy could. This meant that parts played using the 4-bit wavetable synthesis channel in the original tracks were approximated using square waves, leading some parts to sound vastly different. In addition, some tracks had their tempos altered somewhat and other notes in various tracks are not even heard at all.
If active during a Bug-Catching Contest, the GB Sounds will not switch to the old-style version of National Park during the contest results; however, it'll perform the switch after the results are announced.
The GB Sounds does not affect the unused SEQ_DUMMY (played in the Mystery Zones) or SEQ_TEST_TITLE tracks, which are mere copies of the regular Route 29.
Trivia
Although the GB Sounds is unable to play certain old-style themes due to them only being able to play during parts of the game where the player would not have access to this item, if the player cheats in the item early, these themes will still be affected accordingly.
