Apparently it's actually to do with different frequencies, the one going around that says yanny is super high while the one that sounds like laural (which is where this thing comes from) is normal.
Basically someone just screwed with their equilizer settings, recorded the outcome and put it online. Depending on your devices speaker you'll have different results.
This is where it came from:
Different devices: you should be able to hear yanny and laurel
On that note if I were to play it through my headphones I'd probably end up hearing laurel, but given a majority of people are using phones through their speaker, you'll be able to see which phones speaker settings are different
Except the dress was clearly blue, and was proven to be blue, people seeing it as gold had severe issues.
This is basically just a speaker test for everyones devices, if your speaker says yanny then it's playing the sound as whoever edited their eq designed, if it says laurel then your speaker is bass boosting or w/e it is