An MP3 player is a piece of technology made by the Tau'ri which plays music and other recorded sounds. According to Dr. Rodney McKay, a company on Earth produced recordings specifically for the foetus to listen via their mother, allowing the baby to learn music or science. McKay used the idea to record at least two hours worth of his reflections on some of his more ground-breaking accomplishments and theories, afterwhich he gave it to Teyla Emmagan as a "pre-baby present" for her then unborn son. (SGA: "The Kindred, Part 1")