‘It’s true: The sound of nature helps us relax’, https://www.sciencedaily.com/releases/2017/03/170330132354.htm, University of Sussex, ScienceDaily (March 30, 2017)
Outward-directed focus
When listening to natural sounds, the brain connectivity reflected an outward-directed focus of attention; when listening to artificial sounds, the brain connectivity reflected an inward-directed focus of attention, similar to states observed in anxiety, post-traumatic stress disorder and depression. (…) This research is first to present an integrated behavioural, physiological and brain exploration of this topic.