Answer:
singer's language
Explanation:
Leonard Bernstein was widely known as a musical personality in the United States. In one of his Television scripts, titled "Folk Music in the Concert Hall" he asserted that, rhythms and accents in folk music reflect the singer's language, how they talk, and specifically in terms of poetry.
Hence, in this case, according to Leonard Bernstein rhythms and accents in folk music reflect the "Singer's Language"