This is the new "blue dress vs gold dress." People are divided on the answer and cannot fathom how the other side would hear anything but what they hear.
People are so obsessed with this, doctors and scientists have gotten involved.
Brad Story, a professor of speech, language, and hearing sciences at the University Of Arizona says this...
"That first waveform is of the actual recording, which features the primary acoustic features of the “l” and “r” sounds. That leads Story to believe that the voice is really saying “laurel.” The fuzzier image below shows that the recording is of the third resonance of the vocal tract. As your vocal tract changes shape to form different sounds, it produces specific resonances, or natural vibrational frequencies. It’s these resonances that encode language within a soundwave (and thus how you can analyze a waveform and determine speech sounds). (via)"
Going even deeper, part of the reason people are incorrectly hearing Yanny in place of Laurel is that the way we hear sound is influenced by our individual lives. What we hear is largely influenced by what our brains expect to hear.