tolkiens legendarium - How did they determine the music for the songs sung in Peter Jackson's "The Lord of the Rings" and "The Hobbit" film trilogies?

The novels The Lord of the Rings and The Hobbit by J.R.R. Tolkien both contain a number of songs, mostly sung by Hobbits, with fully fleshed out lyrics. A few of these songs even made it into the Peter Jackson movie trilogies, The Lord of the Rings and The Hobbit.

However, as far as I can tell, the actual notes and music to each song never appeared in any of the original books.

Did the production crew for The Lord of the Rings and The Hobbit trilogies make up their own music for these songs? Or was there some reference in a book, letter or transcript to how the songs should be sung?

I'm looking for an answer specific to the movies. This answer to a similar question shows that there was someone writing scores for the songs other than Tolkien, but not whether or not they were used in the movies.

Answer

Ziff-Davis' gaming news website IGN.com conducted an interview with Howard Shore, the composer of the scores for both trilogies, in 2003 in which this very question was asked. IGN concludes that

while the books admittedly provided the initial inspiration, coupled with Jackson's vision, Shore really didn't have any kind of musical source, other than the descriptions contained in the texts and the historical music of European culture some thousands of years ago.

Shore himself stated, when asked what his inspiration was,

"The inspiration of the book ... and Peter and Fran Walsh [screenwriter]'s take on the book. That was the inspiration to me. Richard Taylor from WETA Workshop and Alan Lee [Set Decoration]. Those were the great sources."

In other words, it appears that there was no direct musical instruction for any of the songs; Shore used his own judgment as a composer, in collaboration with Peter Jackson, the script writers, and the set decorators.

(Note: The set decorators and the script writers were consulted in particular because, in addition to the songs, there were particular leitmotifs for many of the characters and props appearing in the movie. But again, there was no actual direction in terms of musical notation that can be traced back to Tolkien himself.)