You may have heard of Kenny G, but what do you really know about jazz? Jazz is a genuinely American art form that has blossomed into a worldwide phenomenon. It is certainly much more than mere background music.

Jazz comes in a wide variety of styles, and has several defining features. The most important of these is improvisation. Jazz musicians do not follow a set piece of music note by note, but make up melodies and chord changes as they play. Such improvisation is based on a musician's creative impulses, and is often inspired by interactions with the other players or the audience. It is this energetic feedback and element of anticipation that gives jazz its incredible dynamism. A piece is never played the same way twice.

The originators of jazz were African-Americans in the early 20th century who fused African rhythms with European ideas of harmony and melody. Jazz's use of rhythm is unique in that it is “syncopated”; that is, the rhythm is irregular. Jazz is also polyrhythmic, which means many rhythms revolve around one basic one.

Another musical genre created by African-Americans, the blues, has heavily influenced jazz as well as rock and roll. About one third of jazz is in blues form with twelve measures in a song and uses ---blue notes,” the flatted third, fifth, and seventh notes of the musical scale.

Jazz has inspired everything from slang such as “cool” and “jazzy”; to dance styles such as tap and swing; to art forms such as filmmaking and beat poetry. Its dynamic nature and strong individual performers have also given rise to different branches of jazz.

Early jazz was centered in New Orleans and had trumpeter Louis Armstrong as its first great soloist. The '30s and '40s saw jazz's sound grow more forceful and invigorating, inciting people to dance. The master of this “big band” or “swing” style was Duke Ellington, thought to be one of America's greatest composers in any genre.

“Bebop” appeared in the 1940s. It introduced more complex melodies, harmonies, and rhythms, as well as more expressive drumming. In the late '40s, Miles Davis ushered in “cool jazz”' s smoother, more harmonic sound. The last of the classic jazz styles, “hard bop,” was more soulful, and sometimes borrowed from R&B and gospel themes.

Later strains of jazz include “fusion,” “bossa nova,” and “funk.” “Smooth jazz,” with Kenny G at its forefront, has proved the most commercially viable form of jazz, although purists scoff at its slick production and lack of improvisation. Regardless of the jazz you have been exposed to, a wealth of it still awaits you. In this era of boy bands, jazz reminds us of what a sublime and rewarding experience listening to music can be.

1. improvisation n. 即兴演出或创作

2. impulse n. 冲动，兴致

3. fuse v. 结合

4. measure n. （此指）小节

5. invigorating a. 令人振奋的

6. strain n. 家系、曲

7. purist n. 纯粹主义者

8. sublime a. 卓越的

你也许听说过凯丽·金，但是对爵士乐你真的了解多少呢？爵士乐是一种地道的美国艺术形式，它已经发展成为一种风靡全球的现象。爵士乐绝不仅仅只是背景音乐。

爵士乐以多种风格出现，具有几种可用作定义的特点。其中最重要的一种是即兴演出。爵士乐手不会按照固定的乐谱一个音符一个音符地演奏，而是在演出的时候自编旋律及变化和弦。这样的即兴演出基于乐手的创作冲动，通常是由与其它乐手或与观众间的互动激发起来的。正是这种充满活力的回应和充满期待的成分赋予了爵士乐不可思议的活力。一首乐曲绝不会有两次相同的演奏。

爵士乐的创始人是20世纪初期的非洲裔美国人，他们将非洲的节奏融入欧洲的和声和旋律的概念中去。爵士乐采用“切分”的演奏是很独特的；也就是说，节奏是不规则的。爵士乐也是多重节奏的，即多种节奏围绕一个基本节奏而进行。

非洲裔美国人所创的另一种音乐类型──蓝调，对爵士乐和摇滚乐都有深远的影响。大约有三分之一的爵士乐采用蓝调形式，一首歌有12小节，使用“蓝音”，即把第三、五、七个音阶降半音（如Ｃ大调的Ｅ、Ｇ、Ｂ）。

爵士乐激发了各种灵感，如：从俚语中的“酷”和“奔放”两个词，到舞蹈风格中的踢跶舞和摇摆舞（即兴爵士舞），以及电影制片和节拍诗等艺术形式。爵士乐富有活力的性质和有很强感染力的个人表演者也导致了不同流派爵士乐的产生。

早期的爵士乐以新奥尔良为中心，并有出色的首席独奏者小号手路易斯·阿姆斯特朗。30和40年代的爵士乐的乐音变得更加强有力、更加振奋人心，把人们跳舞的情绪调动起来了。“大乐团”和“摇摆乐”的大师艾灵顿公爵，被公认为美国各种音乐类型中最伟大的作曲家之一。

“咆哮爵士”出现在20世纪40年代。它引入了更复杂的曲调、和弦与节奏，还有更富有表现力的爵士鼓。40年代后期，迈尔士·戴维斯开创了乐音更流畅、更和谐的“酷派爵士乐”。最新风格的古典爵士乐“硬式咆哮爵士”就更加热情洋溢了，它有时还会从节奏蓝调和福音书中取材。此后的爵士曲调包括“融合爵士乐”、“波萨诺瓦爵士乐”，以及“方克”。

尽管纯粹主义一派嘲笑它的作品媚俗且缺乏即兴创作，凯丽·金为先锋的“轻柔爵士乐”却证明了它是最具商业竞争力的爵士乐类别。除了你曾接触过的爵士乐，它还有大量的爵士等待着你去发掘。在这个男孩乐队当道的年代，爵士乐让我们记起在聆听音乐时，那种超凡而愉悦的体验是多么美好。