This week social media users got into a heated debate over a four second audio file that originated on Reddit and made its way to Twitter:
What do you hear?! Yanny or Laurel pic.twitter.com/jvHhCbMc8I
— Cloe Feldman (@CloeCouture) May 15, 2018
Don’t let the debate get between you and your friends, NIU Audiology professors Danica Billingsly and Charles Pudrith explain what’s happening here is a combo of things:
Your perception of a recorded word is influenced by the language you are exposed to on a regular basis, and the sound system creating the word. A vowel or semi-vowel (such as “r” and “l”) are made up of a group of pitches. When we listen to someone talk, we evaluate how the pitches within a sound are related to another and interpret them into letters. The relationships of these sounds are fairly consistent, but they do vary based on dialects. In this recording, the “y” or “l” is made up of a group of pitches that are close to the middle of where we may expect the pitches for “y” and “l” are to be found based on population averages, which is partially why it is hard to differentiate them.
Regarding the audio quality, those with more high-pitch speakers are more likely to hear “Yanny,” and those with more low-pitch speakers are more likely to hear “Laurel.” This is because we need the high pitches of the “L” to hear it. Filtering out the high frequencies plays with another aspect of interpreting sound called co-articulation. With this phenomenon, not only does our brain compare the pitches within a letter, but it evaluates how these pitches change as we switch letters to help us label them appropriately. Co-articulation is specifically affected by these two words because the highest of the three pitches in “Laurel” shifts it’s pitch over time in a way that is nearly identical to the second highest pitch in “Yanny.” If we don’t have a good audio system, then it is hard to identify the highest pitch in “L”, thereby leading us to be more likely to identify it as an “Y”. Our (sub-conscious) decision to label the first sound is based on how we organize the pitches. Once we make up our minds about the organization of the pitches of the first sound, it forces our brain to evaluate the relative pitches of the second sound in a certain way. Specifically, we will label the second sound in as a “a” in “Yanny” if we hear the first sound as a “Y” or the “aw” of Laura if we hear the first sound as an “L”.
We love this phenomenon because much like the “what color is this dress” challenge, it forces us to realize that our interpretation of something is not the same as everyone else’s. If we can accept things we believe to be true, like the color or a dress or the word in a recording, are open to interpretation, then hopefully we can appreciate how important it is to re-evaluate many of our other pre-conceived truths.