Yiri is in the key of G♭major.
Most of the music is hexatonic (based on a 6 note scale).
The balafons play short patterns that fall from high to low and tend to emphasise the notes G♭ and D♭.
During the choruses, the group sings together and, much like the balafon, they sing short, falling phrases that emphasise the G♭ and D♭ notes.