Contact microphones are a tool used by many sound artists/new musicians to record normally unheard sounds. They do not record airborne sound, but only structure-borne sound – such as the sound the wind makes inside a tree or a phone mast. The sounds discovered in this way are then are either showcased on their own, making an intriguing sub-category within the already fascinating field-recordings genre, or are processed and layered in with other sounds to make composite pieces. Either way, it is as if we are eavesdropping on the secret talk of objects in languages beyond our knowing. The results are often both beautiful and terrifying. Below are a few examples to give a taster. Read more about contact microphones here, and about how musicians make use of them here.