John mayer 3x5 sound?

In the song 3x5 by John Mayer what is that sound in the backround of the song? Its not guitar and its not the drums. It goes da na na na da na na na da na na na da na na na. It sounds something like a harmonica, i looked at his live shows of the song and the sound isn't there. Maybe its an computerized sound, idk please tell this is my fav song from him.