Leafcutter John is a one man recording studio, mixing improvisation and acoustic guitar with special effects.Rarely can the Burgage Hall have heard such weird and wonderful sounds before.A half-empty water bottle, borrowed from a member of the audience, an opening beer can and even a "slinky" spring were used to create good acoustic approximations of trees and sea on Saturday evening.The sounds were fed into a computer, doubled up, distorted, repeated and echoed.He took to the stage with singer Alice Grant, who has an unusual but attractive voice, somewhere between rock and the classical music world.A hard place to be.At times I was reminded of Flamenco and the tradition of "deep song".Their songs were about a journey through a forest, ending at a beach.Musically, they were a little overwrought in places, as though top notes and heavy strummings were standing in for passion.But it was a most interesting experience, and enjoyable too.This was especially so when a member of the audience asked the couple to improvise a song about two adventurous pet rats.You won't hear this song on Classic FM, nor in the charts.But it made people smile, all the same.