New smell discovered: It’s ’olfactory white’ as in white noise
2012 11 21

By Stephanie Pappas | CSMonitor.com

Scientists have discovered a new smell, but you may have to go to a laboratory to experience it yourself.

The smell is dubbed "olfactory white," because it is the nasal equivalent of white noise, researchers reported Monday (Nov. 19) in the journal Proceedings of the National Academy of Sciences. Just as white noise is a mixture of many different sound frequencies and white light is a mixture of many different wavelengths, olfactory white is a mixture of many different smelly compounds.

In fact, the key to olfactory white is not the compounds themselves, researchers found, but the fact that there are a lot of them.

"[T]he more components there were in each of two mixtures, the more similar the smell of those two mixtures became, even though the mixtures had no components in common," they wrote.

White smell

Almost any given smell in the real world comes from a mixture of compounds. Humans are good at telling these mixtures apart (it’s hard to mix up the smell of coffee with the smell of roses, for example), but we’re bad at picking individual components out of those mixtures. (Quick, sniff your coffee mug and report back all the individual compounds that make that roasted smell. Not so easy, huh?)

Mixing multiple wavelengths that span the human visual range equally makes white light; mixing multiple frequencies that span the range of human hearing equally makes the whooshing hum of white noise. Neurobiologist Noam Sobel from the Weizmann Institute of Science in Israel and his colleagues wanted to find out whether a similar phenomenon happens with smelling.

In a series of experiments, they exposed participants to hundreds of equally mixed smells, some containing as few as one compound and others containing up to 43 components. They first had 56 participants compare mixtures of the same number of compounds with one another. For example, a person might compare a 40-compound mixture with a 40-compound mixture, neither of which had any components in common.

This experiment revealed that the more components in a mixture, the worse participants were at telling them apart. A four-component mixture smells less similar to other four-component mixtures than a 43-component mixture smells to other 43-component mixtures.

Categorizing compounds

The researchers seemed on track to finding the olfactory version of white noise. They set up a new experiment to confirm the find. In this experiment, they first created four 40-component mixtures. Twelve participants were then given one of the mixtures to sniff and told that it was called "Laurax," a made-up word. Three of the participants were told compound 1 was Laurax, three were told it was compound 2, three were told it was compound 3, and the rest were told it was compound 4.

After three days of sniffing their version of Laurax in the lab, the participants were given four new scents and four scent labels, one of which was Laurax. They were asked to label each scent with the most appropriate label.

The researchers found that the label "Laurax" was most popular for scents with more compounds. In fact, the more compounds in a mixture, the more likely participants were to call it Laurax. The label went to mixtures with more than 40 compounds 57.1 percent of the time.

Another experiment replicated the first, except that it allowed for participants to label one of the scents "other," a way to ensure "Laurax" wasn’t just a catch-all. Again, scents with more compounds were more likely to get the Laurax label.

The meaning of these results, the researchers wrote, is that olfactory white is a distinct smell, caused not by specific compounds but by certain mixes of compounds. The key is that the compounds are all of equal intensity and that they span the full range of human smells. That’s why roses and coffee, both of which have many smell compounds, don’t smell anything alike: Their compounds are unequally mixed and don’t span a large range of smells.

In other words, our brains treat smells as a single unit, not as a mixture of compounds to break down, analyze and put back together again. If they didn’t, they’d never see mixtures of completely different compounds as smelling the same.

Perhaps the next burning question is: What does olfactory white smell like? Unfortunately, the scent is so bland as to defy description. Participants rated it right in the middle of the scale for both pleasantness and edibility.

"The best way to appreciate the qualities of olfactory white is to smell it," the researchers wrote.


Article from: csmonitor.com










Related Articles
Humans Smell Fear, and It’s Contagious
Psychopaths Have Poor Sense of Smell, Study Finds
Swallowable Perfume Makes Your Sweat Smell Nice
Growing body of research says dogs really can smell cancer
Space Sights and Smells Surprise Rookie Astronauts
The Scent of a Lie
European study says scent can reveal details about personality
Unravelling the Science: Science behind scent


Latest News from our Front Page

U.N. sending thousands of Muslims to America
2014-12-19 0:44
The federal government is preparing for another “surge” in refugees and this time they won’t be coming illegally from Central America. The U.S. State Department announced this week that the first major contingent of Syrian refugees, 9,000 of them, have been hand-selected by the United Nations for resettlement into communities across the United States. The announcement came Tuesday on the State Department’s ...
CIA torture is reason for France to exit NATO – Le Pen
2014-12-17 20:20
The shocking revelations of CIA torture techniques give France a reason to exit NATO, National Front party leader Marine Le Pen said on Saturday. The report on the CIA’s former interrogation practices has drawn wide criticism since its release. “If indeed everyone is outraged by the tortures used by the US then, let’s leave NATO,” Le Pen said during an interview ...
900 Documented Examples of Obama's Lawbreaking, Lying, Corruption, Cronyism, Hypocrisy & Waste
2014-12-17 20:00
Our friend, Dan from Squirrel Hill, has updated his list to 900 documented examples of Barack Obama's lying, lawbreaking, corruption, cronyism, etc. He began with 252 examples, then quickly grew to 504 and later to 694. Recently, he added more than 200 more examples of the usurper-in-chief's unlawful acts. Every President, every politician, and every human being tells lies and engages ...
A Step Closer to the Mysterious Origin of the Viking Sword Ulfberht
2014 12 16
The universe is full of mysteries that challenge our current knowledge. In "Beyond Science" Epoch Times collects stories about these strange phenomena to stimulate the imagination and open up previously undreamed of possibilities. Are they true? You decide. Ulfberht was like a Medieval luxury brand for swords—but unlike your Gucci purse, the swords were of such high quality they were almost ...
Israel proposes natural gas pipeline to Southern Europe
2014-12-16 12:39
Israel is pushing for the European Union (EU) to approve the construction of a pipeline running from the Middle Eastern country to supply Cyprus, Greece and Italy with natural gas. The proposed EastMed pipeline will carry gas from the Tamar and Leviathan gas fields located in the Mediterranean Sea, to Southern Europe. As the Times of Israel reported in an ...
More News »