The rich and varied tradition of Latin American music, with roots in the earthy rhythms of Africa, haunting melodies of Andean Indians and percussive dances of Spain, was barely discernible in the slick new songs presented Saturday night at the OTI International Song Festival in Constitution Hall.

The sold-out concert was the 12th annual international competition for song writers and performers from Spanish- and Portuguese-speaking countries.

While a few of the performer-contestants, representing 21 countries, tried to recall the authentic sounds of Latin America, only the guest artist, opera singer Placido Domingo, in his performance of a medley of Ibero-American standards, was faithful to the musical heritage of the region.

While most of the singers, some of whom had written their own songs, seemed to be emulating Wayne Newton, Domingo's medley of a pasodoble ("Te Quiero Porque Te Quiero"), a tango (Cuesta Abajo) and four other traditional songs brought cheers from the audience. The simple and effective arrangement by music director Hector Garrido contrasted sharply with the overblown orchestration of the other songs.

Two of the top three winners were among those who had managed to incorporate some traditional elements into their songs.

First-prize winner Jesse Florentino Santos' lyrical and soaring tenor expressed modern Brazilian melodic ideas. His winning song, "Paper Star," was written with Elifas Vicente Andreato.

The third-place song, "Your Land and My Land," written by Colombians Santander Di'az and Victor Garci'a (Manoello), bounced among many strong rhythms, eliciting the first strong audience response of the evening.

The Colombian song, interpreted by Jaime Mora, was the only one in the competition with even a hint of the strong political folk protest music that has emerged recently in Latin America. At that, its message was a bland one: "Why don't we love instead of killing? . . . Latin America wants peace."

The second-prize winner, Taty Salas of the Dominican Republic, turned in an energetic performance with the song "Forget, Forget," by Cheo Zorrilla.

Another finalist, Claudius Phillips of the Netherlands Antilles, took his song, "In Each Note Your Voice Will Ring ," in the direction of the English-speaking Caribbean. The audience clapped along with the calypso beat. The song, sung in Spanish, was written with Ricardo del Carmen Gonzalez.