Audiobooks are distributed on CDs, cassette tapes, downloadable digital formats (e.g., MP3 (.mp3), Windows Media Audio (.wma), and Advanced Audio Coding (.aac)).

 

In 2005 cassette-tape sales were 16% of the audiobook market, with CD sales accounting for 74% of the market and downloadable audio books accounting for approximately 9%. In the United States, a sales survey (performed by the Audio Publishers' Association in the summer of 2006 for the year 2005) estimated the industry to be worth 871 million US dollars.

 

Current industry estimates are around two billion US dollars at retail value per year. In recent years, the Internet has introduced another powerful means of delivery for audiobooks and many titles are now available on-line, as downloads and as audio streams. Sometimes audiobook format is available simultaneously with book publication. There are 50,000 titles on cassette, CD or digital format.