Because normally we would have names for voices such as, Bass, Tenor, Alto, Mezzo-Soprano, Soprano.

I believe these terms are used to refers to tenors and baritones respectively, either that or how the voices are structured in group choruses at least. Take the Maison Mere Dream Team Dream Band, for example. Ferre and Lacoste are 1ere voix singers with a tenor voice, while Serge Mabiala and Baby are 2eme voix singers who are baritones. In a chorus, you'd probably make out the 1ere voix/tenors louder than the 2eme voix/baritones, who usually provide background to the choruses. Listen to Robert Basende or Cresois (Solola Bien) so you can catch my drift.

You have tenor (Aimelia, Evoloko, Ferre Gola, Heritier), 1ere voix (Alain Mpela, Oxygene, Fally Ipupa..) and 2eme voix (Pepe Kalle, Werrason, Serge Mabiala, Emeneya,..)

Because normally we would have names for voices such as, Bass, Tenor, Alto, Mezzo-Soprano, Soprano.

The voices on Congolese music are based on Italian Orchestra that's why Wenge was called Musica and groups are called Orchestre in refering to Italian Orchestras and why bands have so many bandmembers because they are trying to replicate Italian Orchestra. 1er voix and 2eme voix are just distinction to differentiate between who has a really deep natural voice and a deep "soft" natural voice

1ere voix is for those who can't do tenor for a long time or their voice being to soft for it. a singer like Aimelia can do 1ere and 2eme voix, but he will never be reffered as 1ere voix singer, because his voice is to high for it. He and musicfans will always refer him as tenoriste. The same for guys like Mustapha Nkori of Quartier Latin, Celezino, Papy Jah and the young Papa Wemba of the Niekesse Miguel-era.