Question

关于英文音乐术语的问题！急！~

请务必用中文（英文更好）解释清楚一点！要特别短！
这是明天音乐考试的内容啊，求求各位大虾帮帮偶啦……
第一个词：Layering
第二个词：One Drop
还有一题是：西非（非洲的西边）的音乐文化在西方世界有很大的影响，How did this happened?
注：最后一题的问题我因为表达的可能不太清楚所以用英语表达了，应该是“怎么会发生”

PS：因为是用英文简答，给的Line才有三行，所以请各位写的短一点，O(∩_∩)O谢谢！

Answer 1

One drop rhythm is a drumset playing style of reggae, popularized by Carlton Barrett (long-time drummer of Bob Marley and the Wailers and The Upsetters), in which the backbeat is characterized by the dominant snare drum stroke (usually a rim shot) and bass drum both sounding on the third beat of every measure in 4/8 time (counting in 4/4 time, the drummer would leave beats one and three open), while beat one is left empty. The high hat becomes the predominant instrument in this style, creating a clean sound that leaves large open musical space for the rhythmic and improvisational contributions of other instruments such as guitar and organ.