Birdsong, for example, is a sound which most people find reassuring.  There is a reason for that. Over hundreds of thousands of years we've learned that when the birds are singing, things are safe.
例えば鳥の鳴き声、これは多くの人に 安心を与えます これには何十万年もの間に我々が 鳥が鳴いているのは安全な証拠だということを学んだからです