You can use the free audio program Audacity to import, record, modify new/existing audio tracks then save them in 1 channel .ogg format.
Then rename the new .ogg file you made as the "pirate announcement" one in the game or whatever they are coded as.
ARESIV, or modern piracy in the form a bunch of crazies on a skiff wielding RPG's and AK-47's! lol