The CD to get is The J.R.R. Tolkien Audio Collection. Here's a description:
Of historic note, these selections from The Hobbit and The Lord of the Rings are based on a tape recording Tolkien made in 1952, which inspired him to continue his own quest to see his vision in print. Also included is a never-published poem, "The Mirror of Galadriel," originally intended for inclusion in the trilogy, yet edited out. And, finally, Tolkien's son, Christopher, reads selections from his father's The Silmarillion, the epic foundation upon which rests the whole of his work.Below are materials free online. A few clips from interviews, followed by several readings, recitings by Tolkien of his own material.
A 47-second clip of an interview about how The Hobbit began in Tolkien's mind:
From a 1968 interview, discussing the Rings mythology:
A nearly 10-minute audio interview (transcript here), broadcast on BBC Radio 4 in January 1971:
Tolkien reads from chapter 5 of The Hobbit:
Tolkien reciting the Ring Verse from "The Shadow of the Past" (LOTR):
Tolkien reading from chapter 4 of The Two Towers:
Tolkien singing "Troll Sat Alone On His Seat Of Stone," the poem recited by Sam Gamgee in "Flight to the Ford" (LOTR):
Tolkien recites an Entish Chant (LOTR):
Tolkien in 1952 reciting the Quenya poem "Namárië," sung by Galadriel in the chapter "Farewell to Lórien" (LOTR):
Tolkien recites the poem "The Hoard" from The Adventures of Tom Bombadil: