I am a fan of MP3 and converted my physical collection to this format . 700 tracks on a usb stick for the car helps drive safely as you don't need to take your eyes of the road to change cd's after 12 tracks or so . However ,I was wondering what is used inside the locomotive to create TTS sound .Is it a mp3 track ?? Maybe somebody knows and can enlighten me and others .I wonder if it can be edited ?