It's back-masked into last year's audio tour. What you're basically gonna wanna do is get a vinyl record pressed of the '07 audio tour, and bring it along with a record player. As you wander along in the desert, wind the record backwards with your finger. The old-style Victrolas work great for this, with their built in speaker... you're just going to need to prepare your arms for their awkward girth and immense weight. And keep the record out of direct sunlight.