Many manmade sounds we are listening to every day, like traffic, aircraft, lawnmowers, construction, etc., can be unnerving and stressful, even when we don't realize the effect they're having on us. At times like this, spending as little a six minutes a day listening to recordings of birdsongs (or better birdsongs in nature if you can get access) will calm our nerves, relieve anxiety and put us in a better mood. Our ancestors lived in nature for thousands of generations and we're hardwired to want to be there as well.