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.