I don't know a lot about them, I've seen them a few times. Here is a link that has sound bytes, in case you want to hear them.
Originally posted by Estragon
...If you really love this sound, I might mention an English chap who made several recordings of these: one was a CD called Shambala with an entire piece scored for an orchestra of these artefacts.
I believe it's still available here: www.frankperry.co.uk...