Simplify the following text for a Grade 7 native English-speaking person.
Original: In 1994 , an edited version was released as the four cassette audiobook Pop Chronicles the 40 's : The Lively Story of Pop Music in the 40 's .
Simplified: In 1994 , Gilliland released a shorter version on audio cassette . The title of this audiobook was Pop Chronicles the 40s : The Lively Story of Pop Music in the 40s .