If you get a pass at the kiosk down the hill, you do get an audio guide - along with admission to other sights in Granada.
I have to confess I only picked up my pass there because I arrived in town without any reservations. I travel without a set itinerary and book hotels (from a list I prepare before the trip) as I go. I couldn't commit to a reservation because I wasn't sure which days I'd be in Granada. The only thing I normally know for sure is the flight to Europe and back, and the lodging for the and last night there.
For this trip, I wanted to ride the AVE so booked a ticket 60 days in advance and added hotel reservations before and after that as well.
To see the Alhambra without reservations, I followed the advice in Rick's book, I first went to the bookstore. They had nothing, not even a night tour. Next option was the kiosk which was perfect, they gave me admission for 9 AM the next morning. You pay a little more at the kiosk but, as I said, it includes an audio guide and admission to many other sights.