There a number of questions that you didn't answer. For instance, where are you recording where the GPS has been? How are the two Arduinos communicating? What is the criteria for "I've been here before"? The exact same lat/lon value, or some threshold? How big? 10 feet? 10 miles?
Do you know how to read data from the GPS? How is it connected to the Arduino? Which pins does it use?
Do you know how to make the Wave shield play a file?
I'm using two Arduinos due to noted conflicts between the libraries of the GPS and Wave Shields.
Noted by whom?