Smallest Arduino which can play WAV files and read values from sensors

Projects General Guidance
2

Get an MP3 module and control it from Arduino.
examples:
http://www.mdfly.com/index.php?main_page=advanced_search_result&search_in_description=1&zenid=255505053fe0061f376e9f48682ccd03&keyword=mp3&x=0&y=0