The clip is an auditory illusion in which more than 50% people heard the Laurel while the rest heard Yanny.
The latest head-splitter however is one step ahead. It is this small toy and what you hear is based on what you think.
Between the words ‘brainstorm’ or ‘green needle’, the toy speaks what your brain first picks.
Check here:
You can hear the words ‘Brainstorm’ or ‘Green Needle’ based on which word you think about. Try it.
How does the audio clip waver between the choice your mind thinks of ?
The set-up functions on the laurel-Yanny principle.
With very precise change in pitch and every individual’s sensitivities to certain pitches, different people heard different words in the Laurel-Yanny audio.
In the brainstorm-green needle case, the selection of frequencies are so closely balanced along the pitch line that just a thought about it makes the listener hear one or the other word as long as the brain is primed to think of the options.
Also you must have noticed that the quality of the audio is not very crisp. The noise in the clip helps disguise the pitch fluctuation.