"阳春白雪" 与 "下里巴人" 都是古代楚国的歌曲名, 分别指是高雅的宫廷音乐和民间的通俗音乐, 一个高雅清丽, 一个活泼灵动, 都是表达真实感情的曲目,因而得以丰富和发扬至今。请注意“下里巴人”中虽有一个“人”字,但并非是指人,而是指歌曲。
阳春白雪和下里巴人 is a pair of two aspects, being used in many places and translation varies accordingly:
For general, you can say "highbrow" & "lowbrow"
For music/songs, it's "classical" & "pop music/pop song" ("美声"和"通俗"就是一例).
For social groups in western world: noble & populace.
...
If we are just talking about the specific music "阳春白雪", it can be translated into "Sunny Spring & White Snow" or just "The Spring Snow".
I haven't heard the specific music "下里巴人", I'm not sure if it really exists nowadays.
Here is 古筝"阳春白雪":
http://www.chinakongzi.com/2550/music/download/guzheng/hangongqy.mp3
**Note: Please take this as a reference only. Welcome corrections.