This is a joke! It’s Yanny (or Yammy) every time. Without fail.

I was interested in this joke too. I downloaded the sound to the sound editor (Adobe Audition) and tried various filters on it: Equalizer of low and high frequencies, change of speed, change of tone and pitch - no doubt: all the time Yanny (without any additives Laurel) and only where the allegedly "pitch up 30%" - is really recorded Laurel (without any additives Yanny). So this is just a science-like joke.