The internet is freaking out over an audio “illusion” that went viral after appearing on Reddit. Dubbed the audio version of the blue-or-gold-dress debate, it asks whether people hear the word “laurel” or “yanny.” Twitter users are baffled over the divide. “My wife heard yanny. I hear laurel. How is it possible that people can hear one word or the other? What’s the science behind that?” one confused listener wrote. According to the Verge, it’s not actually an illusion–the secret is frequency. Yanny is in higher frequency, while laurel is in lower frequency. You will hear one of the words depending on which frequency your ears pick up on. Older adults tend to start losing their hearing at the higher frequency ranges, so it’s likely that most children will hear the word yanny. What do you hear?