Natural sounds such as birdsong and the sound of water have been used in stressful situations like surgical procedures, and have demonstrated stress-relieving effects via the autonomic nervous system (Annerstedt et al., 2013).
A randomized study by Bauer and colleagues (2011) found that nature sounds and music, compared to no sound, had the potential to reduce pain and stress significantly in cardiovascular surgery patients.
One study found that nature sounds, compared to noise, facilitate recovery from stress after a stressful mental arithmetic task. Stress levels were measured by people’s skin conductance levels (Alvarsson et al., 2010).
Another study found that sounds of a soft wind and a twitter during epidural anesthesia, compared to no sound, reduced stress. Reductions in stress were reflected by a decrease in salivary amylase activity (Arai Y-C et al., 2008).
A recent experiment by Annerstedt and colleagues (2013) found that participants, exposed to natural sounds in a virtual natural environment, showed enhanced stress recovery after a virtual stress test.
The authors used cardiovascular and saliva cortisol data, and they found that natural sounds, combined with a virtual natural environment, increased stress recovery by activating the parasympathetic nervous system.