The total length of the audio book versions of the immensely popular ?Harry Potter? series, for instance, is 117 hours and four minutes. According to officials at Listening Library, the Random House division that publishes the audio books, it would take five days to listen straight to all seven books. The final audio book in the series, ?Harry Potter and the Deathly Hallows,? alone, s 21 hours, 38 minutes long and consists of 17 CDs or 12 audio cassettes.

The narrator for all seven ?Harry Potter? audio books is English actor Jim Dale, who has won Grammy awards for his performances of more than 200 characters in the fiction series. He holds the record for creating the most voices in an audio book in the Guinness Book of World Records. Recording audio books is tricky, says Dale, who only saw his material two or three days before his recording was to begin. And he never knew where the story was going as he never got the chance to read the entire book before he started. On a good day, Dale read the audio books at a rate of 18 to 20 pages an hour, from 9 a.m. to 4 p.m. with several breaks to protect his voice. It usually took ten days to complete the audio book recordings. The published print version of ?Harry Potter and the Deathly Hallows? is 784 pages, and it required almost two and a half weeks to record the audio book.

The publishers kept digital files of all the voices Dale used so that he could recreate them for each audio book. But he had to take into the account the aging of the main characters Harry, Ron and Hermione, who started out as 10 and 11 in ?Harry Potter and the Sorcerer's Stone? and who are now 17 and 18 in ?Harry Potter and the Deathly Hallows.? For new characters, Dale used a tape recorder to record one or two sentences in a new voice and noted the place in the text. At the studio he would rewind until he found the right voice and play it back to refresh his memory before recording the audio book.

The producers were great sticklers to being absolutely verbatim to the text of the audio books, and Dale admits there were many mistakes, especially when he stumbled on words not on the author's list. He would have to record it in context in several ways to account for every possible pronunciation. ?If she says ?someone laughs, ha, ha, ha, and I do four ha's,? I am stopped and told, ?Just do three,? says Dale.