I purchased at a street fair a CD of Peruvian Pan Flute music. It's very soft and airy, no singing or lyrics, nothing dramatic, loud, distracting...no sudden noises, everything flows nicely. Very calm.
It's definitely relaxing and soothing, and makes me more comfortable while I speak. I did, however, decide to rearrange (via burning) the order of the songs to better suit my preference. I found it to be perfect for my relaxation and guided imagery.
Here is an example of similar music (again, the peruvian panflute). This isn't from the CD that I own, but very much like it.
I'm sure you could purchase something like this on amazon.com or a similar website--or maybe even rent something at the library. Or, if this doesn't do it for you, check out your local library and just go to the classical section. Listen to a few CDs/songs and practice at home when you find one or two that you like. You can then purchase your own or bring the library copy with you.