As in any world, Middle Earth has music. While mentioned at many points during the trilogy, J. R. R. Tolkien does not really discuss it.
However Appendix F, “On Translation”, provides a variety of evidence to try and reconstruct his views. In this essay, he describes the differences between the languages of the various races present in Middle Earth in terms of the various predecessors to modern English. English is the spoken language in the Shire, Gondor, and in Rohan – although slightly different dialects seem to be used. The speech of the Stoors and Bree-men, and therefore the Dunlanders, is Celtic. Tolkien states that the Elven languages play the role of Greek and Latin, but even the untranslated songs in Sindarin and Quenya follow his Germanic patterns exactly.
In 597 Pope Gregory sent missionaries to convert the Germans to Christianity. While doing so, they also educated them to write and translate their spoken language into writing. Before 597, these Germanic peoples had maintained a spoken literature, which they chanted or sang to the accompaniment of small harps. These songs told stories that commemorated heroic deeds. They were made up of unrhymed rhythmical verses joined together within by alliteration. "Lament for Theoden" and "Song of the Mounds of Mundberg" are good examples of this style of song and by correlation can be taken to characterize the earliest appearance of music – apart from birds and the like - in Middle-earth.
Tolkien was particularly fascinated by Old English literature from "Beowulf" to "Gawain and the Green Knight," which stand at each end of the Middle Ages. In "Gawain" the change to metrical rhyme isn’t yet absolute. The main stanzas are alliterative, followed by short rhymed stanzas. In LOR, although most lines are rhymed, they are not yet completely metrical. Nearly all have pauses – caesurae - near the middle of each line, even when they are fairly metrical otherwise. The caesurae split each line into half lines. "Galadriel's Song" has two caesurae per line, dividing each line into thirds.
The music not having metrical form and the presence of the caesurae create particular difficulties in trying to compose or recreate true music for Middle-earth.
In the earlier times in our world, the style of music formed to deal with the Germanic poetry and verses was Gregorian chant, one of several types of plainsong. This was a Monophonic chant in unmeasured or free rhythm – very different from the more modern measured music, which sets the notes into regular bars of same duration. Monophonic music means a single line, or melody/tune without an accompaniment that was part of the work itself. Examination of the irregularity of the verse, there is little doubt that the music in LOR was almost completely sung in free rhythm, probably chants, though there is some evidence that some of the verses could have been set to a Ballad style melody. Ballads, however, correspond to a different era in our own history, and also would have mostly had an accompaniment, however simple it might be.
Careful examination of the text by Tolkien also reveals that in almost all cases songs were sung without musical accompaniment. One of the very few exceptions to this rule is the music of the Dwarfs in Bilbo’s house. Perhaps this style of music is purely from that race – or perhaps more likely, it is simply an inconsistency between the earlier, and the later, more carefully considered work.
In the words of Tolkien, everyone was “"intent upon the music of the voices and the instruments" and "the beauty of the melodies and the interwoven words." When Bilbo begins to sing, the "dream of music" changes "suddenly into a voice." These observations suggest that the instrumental and vocal music were identifiably separate and probably did not occur at the same time.
Supposing that polyphony was – multiple lines of melody at the same time - at most very uncommon in Middle-earth at the time of LOR, a valid reconstruction of a song should be a single melody line without instrumental accompaniment. However, for those who are so used to homophony – a melody line accompanied, at the least, with instrumental chords – to completely appreciate an ongoing length of unaccompanied voices, some compromise with authenticity may be made
As for musical instruments in Middle-earth, the Dwarves play "little fiddles," "flutes," "clarinets," "viols," "drums," and a "harp." "Durin's Song" mentions "harps" and "trumpets." There is also mention of the elves performing on harps, and flutes as well. Vocal seems to be more common.
In the Middle Ages, the harp was a basic instrument that was strummed between lines in Germanic verses.
The fiddle was a bowed stringed instrument, played on the shoulder or arm, but sometimes played upright in the lap like a viol.
A viol was simply a larger version of the fiddle, held upright on the knee. It is not an ancestor of the Renaissance instrument and it is a contemporary, not an ancestor of the early violin.
The flutes were most likely recorders or "blockflutes," the flute most commonly used in the Middle Ages for the accompaniment of dance and song.
The clarinet was probably slightly bigger than the recorder and distinguished from it primarily because it used a reed.
Trumpets were not musical instruments, since, like the bugle, they could produce only a limited number of notes and were therefore used primarily for fanfare.
Percussion instruments could be anything and started in folk music with the banging of pots and pans, though they developed rapidly into more complex instruments – eg Tambourine.
Overall, the music in Middle-Earth, while not being hugely discussed, shows a lot about the culture and history of its people. Although it is completely different to modern music, it shares extreme similarities with our own Middle Ages music. Perhaps this indicates that Middle-Earth, and Our Earth, had similar cultures at some time. Because of the differences between the style of music, and our own music, there are many difficulties in composing music inspired by it. One must decide whether the music is to be authentic to the style, or modern day but inspired by Tolkien. It seems that most inspired composers have tried compromises between the two.