The article is wrong (edit: it might be more complicated; see discussion below). The reason you can hear both is because someone took the high frequencies of "yanny" and combined them with the low frequencies of "laurel". If you apply appropriate high-pass and low-pass filters, you will consistently hear yanny and laurel respectively (assuming your speakers/headphones are capable of reproducing all the required frequencies and your ears are capable of hearing them). Essentially, it's the audio equivalent of the Einstein/Monroe illusion [1]. So this audio illusion doesn't imply that yanny sounds like laurel any more than the visual illusion implies that Einstein looks like Marilyn Monroe. It might be incidentally true that yanny and laurel do in fact sound similar (and this may in turn make the illusion more convincing), but you could probably do the same trick with any two words that have similar cadences, no matter how different they sound.

[1]: http://www.123opticalillusions.com/pages/albert-einstein-mar...