"This is an excerpt from the record Years, created by Bartholomäus Traubeck, which features seven recordings from different Austrian trees including Oak, Maple, Walnut, and Beech. What you are hearing is an Ash tree’s year ring data. Every tree sounds vastly unique due to varying characteristics of the rings, such as strength, thickness and rate of growth.
Keep in mind that the tree rings are being translated into the language of music, rather than sounding musical in and of themselves." (more here)