For this week's episode we're back in the Forest of Dean for a different kind of captured quiet. Quiet that transforms from one thing to another. A kind of sonic metamorphosis. 
The segment from this overnight recording begins at around 4am when the space around the oak tree holding the microphones is still pitch dark, and pristine quiet. Intimate. A clearing, deep within an expansive forest, where the night air carries so little sound that only the trickling stream can be heard. It reflects narrowly off the trunk of the tree, like the flickering light of a campfire. But when a woodcock flies by, on its *roding flight, the sense of pristine space is temporarily revealed.
This sense of closeness, of being beside an old oak tree and a trickling stream, surrounded by dense and tangled undergrowth, continues, occasionally graced by the distant hooting of an owl, and a passing high altitude passenger plane.
But then, something in the forest changes. Strange new sounds, floating in, from far beyond. Fragments of distant birdsong. Filtered through countless trees, countless empty voids. Echoing, and reverberating. The intimate space, thinning, giving way, opening out, and lightening, through the gathering sound.
A song thrush, heard left of centre of scene, sings out and becomes the first real soloist of this newly evolving place. Widening. Expanding as each new bird joins in song. The proportions of the space growing, from an amphitheatre. Then, to a cathedral. 
* In late spring male woodcocks make roding flights to attract females. Just after dusk and just before dawn, they fly at speed through the treetops making a combination call that sounds like a quack that ends with a squeak. This recording captures the roding flight in 3d spatial audio and so reveals the way the bird is moving.