电视剧《回响》里徐山川在KTV里唱的歌是《What a wonderful world》，中文译作《多么美好的世界》。

这首歌是美国歌手路易斯·阿姆斯特朗(Louis Armstrong)于1967年9月作为单曲发行。该曲的意境感人，它告诉世人，只要肯付出一点爱和关怀，就会发现世界的美丽，爱可以改变一切。

《What a wonderful world》歌词

I see trees of green, red roses too
我看见绿树和红玫瑰

I see them bloom for me and you
我看见他们为你我开放

And I think to myself, what a wonderful world
我情不自禁地想到，这是一个多么美妙的世界

I see skies of blue and clouds of white
我看见蓝天和白云

The bright blessed days, the dark sacred nights
明亮而幸运的白天，深邃而深沉的夜晚

And I think to myself, what a wonderful world
我情不自禁地想到，这是一个多么美妙的世界

The colours of the rainbow, so pretty in the skies
天上的彩虹的颜色如此美丽

Are also on the faces of people going by
照映在过往人们的脸上

I see friends shaking hands, saying' "How do you do?"
我看见朋友们握手问好

They're really saying "I love you"
他们真的在说：我爱你

I hear babies cry, I watch them grow
我听见婴儿哭泣，看着他们长大

They'll learn much more than I'll ever know
他们学到的东西将远胜于我

And I think to myself, what a wonderful world
我情不自禁地想到，这是一个多么美妙的世界

Yes, I think to myself, what a wonderful world
我情不自禁地想到，这是一个多么美妙的世界