It's all got to do with the frequency. As we get older, we tend to start losing our hearing at higher frequency ranges. In the audio clip, the word "Yanny" is being created by acoustic information which is at a higher frequency than "Laurel" is. Lars Riecke, assistant professor of audition and cognitive neuroscience at Maastricht University, told The Verge the audio clip was ambiguous. "The input can be organised in two alternative ways," he said. So if you pitch shift the audio clip a little bit to hear more of either the higher and lower frequencies, you should be able to hear the two words.
