An audio book is a work recorded by one or more people in different voice expressions and recording formats according to the manuscript. Common audio book formats include audio tapes, CDs and digital files (such as MP3). The word "audio books" appeared in about 1980' s, which means books with sound to express content. Audio books are mainly published by audio book publishing house or blind book club. A book with sound depends on the speaker's voice. The speaker is the medium of the audience and the manuscript, and the speaker's voice has the essence of attracting and fascinating the audience. The content of audio books can be reading aloud, broadcasting dramas, or special reports.