I hear Laurel. I played the original clip over and over again and I only hear "Laurel." Then my friend Josh, who's on our sister station in DC, broke down HOW YOU CAN HEAR BOTH!
The difference seems to arise because the voice that says "Laurel" is deeper than the one that says "Yanny". So people will be predisposed to hearing one or the other, for a variety of reasons.
Younger people, for instance, are generally better at hearing higher sounds. So younger people will be more likely to hear the Yanny voice.