Hey, are you looking book "The Road Goes Ever On: A Song Cycle"?

With Tolkien's approval, Donald Swann wrote the music for this song cycle, and much of the music resembles English traditional music or folk music. The sole exception is the Quenya song "Namárië," which was based on a tune by Tolkien himself and which has some affinities to Gregorian chant. This book has been valued even by those uninterested in the music, since it helps Tolkien's readers to better understand the cultures of the various mythological beings presented in Middle-earth, and helps linguists analyse Tolkien's poetry. For example, it contains one of the longest samples of the language Quenya (in the song "Namárië"), as well as the Sindarin prayer "A Elbereth Gilthoniel" with grammatical explanations. Also, in addition to the sheet music, the book includes an introduction that contains additional information about Middle-earth. Prior to the publication of The Silmarillion, this introduction was the only publicly available source for certain information about the First Age of Middle-earth.[1]