Laurel or Yanny?

Supposedly, the audio clip was recorded from a vocabulary website (vocabulary.com), from a male voice pronouncing the noun “laurel”, but playing through speakers. But how come some people hear “Yanny”, when it should be “Laurel”?

Hearing high and low frequencies

This may have to do with the ‘technical’ properties of the sound, says Hans Rutger Bosker, psycholinguist and phonetician at the MPI. Analysis of the frequencies in the sound suggests that the higher frequencies (>1000 Hz) are more like “Yanny”, but the lower frequencies (<1000 Hz) are more like “Laurel”. It could be that playing “laurel” over speakers and re-recording it introduced high frequency noise in the recording, which emphasized the higher frequencies. Now some listeners (for instance, young adults vs. older adults) are simply better at hearing these higher frequencies, or weigh them more heavily in perception than others, leading ‘high-frequency’ people to report Yanny, where ‘low-frequency’ people hear Laurel.

Not quite Yanny or Laurel

Interestingly, this social media hype is a great example of the kind of stimuli Bosker and fellow psycholinguists use in their experiments. “The sound is ambiguous: it is not quite Yanny and it’s not quite Laurel; it’s kind of in between”, Bosker explains.  Series of ambiguous speech sounds are used very often in psycholinguistics to understand the acoustic cues people use to perceive the ‘letters of speech’. Often researchers take one word (a clear Yanny) and another word (a clear Laurel) and artificially create sounds that fall in between those two endpoints. This is called a phonetic continuum, typically varying one particular acoustic dimension (for instance, the intensity of some frequencies, the duration of segments, etc.).

Here’s how this would work for the Laurel/Yanny sound. First reducing the higher frequencies, and then gradually step-by-step emphasizing the higher frequencies, leads to a continuum from more Laurel-like (step 1; reduced higher frequencies) to more Yanny-like (step 6; emphasized higher frequencies).

Listen to the succeeding steps:

Step 1    (most Laurel-like)

Step 2   

Step 3   

Step 4   

Step 5   

Step 6    (most Yanny-like)

A similar continuum can be created for many speech sounds. To demonstrate this especially for our readers from the British Royal Family, here’s a 3-step continuum from Harry-to-Meghan. It combines the higher frequencies from Harry with the lower frequencies from Meghan. Step 1 is more Harry-like because most of the high frequencies are from Harry. Step 2 is kind of in between, and Step 3 is more Meghan-like, with the high frequencies mostly from Meghan.

Step 1    (most Harry-like)

Step 2   

Step 3    (most Meghan-like

Surrounding acoustic context

But can we actually make a person listen to the same clip twice and make her hear Laurel once, and Yanny the next time? Yes, that’s possible. “We know that the perception of speech sounds is influenced by the surrounding acoustic context. The same sound can be perceived differently when, for instance, the acoustics of a preceding sentence are changed,” Bosker says.

To demonstrate this with the Laurel/Yanny sound, Bosker designed a short online experiment in which listeners heard the same Laurel-to-Yanny continuum as before, but this time preceded by a 7-digit telephone number (496-0356). So people heard things like: “496-0356 Laurel”. Sometimes the higher frequencies in the digit sequence (>1000 Hz) were attenuated (filtered out; low-pass filter at cut-off frequency of 1000 Hz), sometimes the lower frequencies were attenuated (high-pass filter at cut-off frequency of 1000 Hz).

Bias by previous sounds

The results from more than 550 listeners from all across the globe show that on the side of the continuum with reduced higher frequencies, most people report Laurel (low proportion Yanny responses), and on the opposite side of the continuum (emphasized higher frequencies), most people report Yanny - in line with what Bosker argued about the continuum.

The acoustics of the lead-in telephone number can actually bias participants’ perception: when the phone number has the higher frequencies attenuated, this makes the higher frequencies in the Laurel/Yanny continuum stand out more, leading to slightly more Yanny responses in the low-pass condition (i.e., the blue line is above the red line). Similarly, when the lead-in precursor has the lower frequencies attenuated, this makes the lower frequencies in the Laurel/Yanny continuum stand out more, leading to more Laurel responses in the high-pass condition.

So what did Bosker conclude? Artificially emphasizing the higher frequencies leads to more Yanny responses (as evidenced by the continuum). Moreover, making people more sensitive to the higher frequencies in the Laurel/Yanny word by attenuating higher frequencies with an introductory sound also leads to more Yanny responses. But maybe the most striking conclusion of the entire the Laurel/Yanny hype is that it shows that even psycholinguistics can be a trending topic on Twitter.

More information

•  Want to try this online test yourself? Visit: https://www.psytoolkit.org/cgi-bin/psy2.4.3/survey?s=NEUE6

Questions? Contact:

Hans Rutger Bosker

Phone: +31 24 3521373

Email: HansRutger.Bosker [at] mpi.nl (HansRutger[dot]Bosker[at]mpi[dot]nl)