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

Ingraham to Zuckerberg: Time for Open Borders at Your Mansion
2014 09 19
Talk radio host Laura Ingraham re-iterated her challenge to debate Facebook co-founder and CEO Mark Zuckerberg and criticized him for securing his property while demanding the US allow illegal immigrants to remain in the country on Monday. “In the end, borders work for these guys. Right, I would not want to be on [Facebook board member] Marc Andreesen’s household staff if ...
MasterCard tests Orwellian national ID card on Nigeria
2014 09 19
The march toward enslaving the world’s population by a handful of globalist statists and corporations continues, with the latest chapter unfolding, of all places, in Nigeria, compliments of MasterCard. According to the website GovtSlaves.info, the credit card giant is rolling out a card in Africa’s most populous country that has the ability to retain all personal, health insurance, tax payment and ...
Doctor: Gov’t ‘Tight-Lipped’ on Respiratory Virus, May Be From Illegals
2014 09 19
Dr. Jane Orient, Executive Director of the Association of American Physicians and Surgeons, reported that the government has been “real tight-lipped” about the mysterious respiratory illness that has struck children in the United States, expressed concern that the illegal immigrant minors from Central America could be the source, and argued that the government should devote more resources to border security ...
Breaking—CDC whistleblower: “I’ve stopped lying”
2014 09 18
Explosive…explosive…explosive… What more could anyone want in the way of evidence for an ongoing crime? There is a video posted at the autism media channel/YouTube, and at Age of Autism: “William Thompson’s call to Congress.” It is a recording of a telephone call between CDC whistleblower Thompson and Brian Hooker, PhD. No date is given. Presumably, the call was recorded before August 27, when ...
Ebola patients buying survivors’ blood from black market, WHO warns
2014 09 18
As hospitals in nations hardest hit by Ebola struggle to keep up, desperate patients are turning to the black market to buy blood from survivors of the virus, the World Health Organization warned. The deadliest Ebola outbreak in history has killed at least 2,400 people in Guinea, Liberia and Sierra Leone -- the countries most affected by the virus. Thousands more are ...
More News »