newshour's nsikan akpan and julia griffin explain how one sound can create two different experiences. (sound playing) >> the internet has been set ablaze over one sound and two wordau >> laurel, ll, laurel. so >> which did you hear? yanny or laurel? this audio clip, which first went viral oreddit and then twitter, features a robotic voice saying a specific word, but people's perceptions of that word differ dramatically. even in the newshour oice. how is it possible people are hearing different things? the sound is what's called an ambiguity illusion, and it's nothing new to neuroscientists. >> remember the dress from 2015? some people swore it was gold and white, others, black and blue. that viral photo is a visual version of an ambiguity illusion. >> when a human brain encounters something it can't immediately understand, it tries to fill in the gaps. >> in the case of yanny v. laurel, the frequency, or pitch, of the sound clip is cryptic to our minds. the original poster of the audio clip, 18-year-old reddit user from lawrenceville, georgia, recorded the pronunciation of "laurel" of