Beren has posted a transcript of an interview with Tolkien on his web site http://www.tolkienlibrary.com/press/8 ... en_1971_BBC_Interview.php and mentioned finding these recordings by looking on the Internet.

A good place to start is the New York Times which has quite a lot of Tolkien material including original book reviews, his obituary and a video interview with Raynor Unwin. Be aware that not all the links still work (sadly the Tolkien Audio link does not work, but I think from memory it is the Interview above) but I recommend you take a look.

http://www.nytimes.com/specials/advertising/movies/tolkien/