The always interesting Ask Metafilter has a post asking the question, Are there any extant recordings of Samuel Beckett's voice?. So far there's no answers that excite me, although there's a link to a 150 MB .avi of Not I.
I've previously written about my search for Beckett recordings here, here, here, and here.
The most exciting bit of information I've turned up in a long time was actually found in my own damn comments about twenty minutes ago. In the next to the last post I mentioned above, I just saw an anonymous comment I'd overlooked left by someone in 2004 with a UK email address:
There is a recording of Beckett's voice on VHS: "Peephole Art: Beckett for Television" it was put out by Global village NY telephone 212 925-7751Beckett for Television is available, but for a terrifying $45. (Don't the people who put these things out realize that cheapskates want this stuff, too?) The description doesn't seem to mention a recording of Beckett himself. It's also available (and described) here.
I don't know if this still works
The British library in London also had (has?) a sample from this film on its Voicebox in the foyer