Recently, the story with a white-gold or blue-black dress received its unexpected continuation, but only in the form of sound perception. An audio fragment synthesized by schoolchildren using a web dictionary was posted on reddit and in Instagram. The essence of the snippet is that different people hear different words while listening to the same file. 'Yanny or Laurel? How a Sound Clip Divided America '. Evgeny Vildyaev shared this note with me in The New York Times and asked me to comment on what I think about it.
The analysis of the recording was carried out before me by taking a spectrogram and finding out that the word 'Laurel' is pronounced at low frequencies, while the version of the word 'Yanny' stands out most at higher frequencies. The original audio clip presented on the web is an equal mixture of low and high frequencies.
The New York Times even created a tool to remove high or low frequencies. And despite this, many still fail to hear both words.
In this story I was interested in something else – why is this happening? Why do some people hear one version of the word, while others will claim to hear something completely different.
First, let's try to remember what hearing is and how it works.
We know from the school course that hearing is the ability of biological organisms to perceive sounds with the organs of hearing; a special function of the hearing aid that is generated by sound vibrations in the environment, such as air or water. One of the biological distant sensations, also called acoustic perception. Provided by the auditory sensory system. (Wikipedia).
Acoustic (sound) signals, which are vibrations of different media with different frequencies and strengths, excite auditory receptors, which are located in the cochlea of the inner ear. These receptors activate the first auditory neurons, after which sensory information is transmitted to the auditory cortex.
Image via gidmed.com
It is believed that, given the imperfection of human organs of perception, and hearing in particular, we hear much less than we think, and that a significant percentage of acoustic information is lost on the way of conversion into an electrical signal, and as a result, only part of the information received reaches the brain. Why then do we still hear and understand what we hear? Scientists explain this by the fact that our brain completes the missing piece of information on the basis of the existing knowledge base, or, in simple words, comes up with it. This, incidentally, explains why people continue to understand speech even in the late stages of the development of hearing disease. Speech in the native language is the most familiar sounds for most people, and the accumulated baggage of knowledge is enough for the brain to fill and conjecture even tangible losses. This is true not only for hearing.
Here is a well-known example of a similar feature of perception, only for sight (thanks to Andrey Podkin for the tip):
'Did you know that …
According to rzelulattas, Ilsseovadny odongo anligysokgo unviertiseta, do not have a problem, there are bkuvs in solva. Galvone, chotby preavya and psloendya bkwuy bla on msete. Osatlyne bkuvy mgout seldovt in ploonm bsepordyak, all torn tkest chtaitseya without wandering. Pichriony egoto is that we do not chiate every day, but everything is solvo tslikeom. '
But back to the sounds.
It is generally accepted that a person is able to hear sound in the range from 16 to 20,000 Hz.
This range is also called the audible range. However, we are all different, and, as is often the case, the level of development (acuity) of hearing may differ from person to person.
Someone hears this entire range and even a little more, and for someone even half of these frequencies is the limit above which their auditory sensory system will not be able to pick up.
It is for this reason that it is often possible to face the fact that different reviewers and testers of audio equipment give different ratings to the same product, while managing to argue with each other, proving their point of view. If we consider this issue from the point of view of the difference in hearing with them, then everything becomes clear. It is not clear only why.
This may be due to various factors, ranging from congenital features and ending with traumas, diseases and their complications, which affected hearing acuity.
In addition, studies show that not only random factors, such as the diseases and injuries described above, but also quite natural processes, such as common but inevitable aging, can affect the width of the audible range. It is known that hearing acuity decreases with age, and the ability to hear high frequencies is responsible for acuity. No, of course, if you remove the upper frequencies, above 15-20 kHz, you will not stop hearing at all, but the detail … There will be almost no detail. By the way, did you know that only children can hear the 20 kHz frequency? This is so, alas.
But why do we start to hear worse with age?
The cochlea contains fluid and auditory hair cells. The vibrations set in motion the fluid in the cochlea. The fluid sets in motion the hair cells, which already convert the sound vibrations in the fluid inside the cochlea into electrical signals, which are then transmitted by the auditory nerve to the brain.
Image via gorlonosik.ru
With age, many people develop presbycusis, a form of sensorineural hearing loss that occurs as a person ages. The most common form is sensory presbycusis. It is expressed in destructive changes in hair and supporting cells, which is most pronounced at the base of the cochlea, where the cells responsible for the perception of high-frequency sounds are located. It is for this reason that, with age, a person often begins to hear high frequencies worse.
Coming back to our 'Yanny' and 'Laurel', things become a little clearer. It can be concluded that people who hear 'Yanny' have a sharper hearing, since 'Yanny' is recorded in the high frequency range. But people who hear 'Laurel', on the contrary, do not have such a keen ear, so for them the low frequencies, in which 'Laurel' is recorded, become the main ones.
Thus, we can assume that all this hype, supposedly dividing humanity into two parts, hearing different words, has its own rather simple rational explanation, which has nothing to do with the fact that we are all different, unique, etc. And, however, this self-explanatory explanation can be a little offensive to those who only hear 'Laurel'. Perhaps the fact is that only 'Laurel' hearers are not as sharp as those who hear 'Yanny'.
Knowing all this, you begin to better understand the reasons why such 'phenomena' are possible, and you learn to treat them with a fair amount of skepticism.