Weizmann Institute scientists apply the principles of white color and white noise to create a white smell
You can see the color white; you can hear white noise. Now, Weizmann Institute researchers show that you can also smell a white odor. Their research findings [1] appear online this week in the Proceedings of the National Academy of Sciences (PNAS).
The white we see is actually a mixture of light waves of different wavelengths. In a similar manner, the hum we call white noise is made of a combination of assorted sound frequencies. In either case, to be perceived as white, a stimulus must meet two conditions: The mix that produces them must span the range of our perception; and each component must be present at the exact same intensity. Could both of these conditions be met with odors, so as to produce a white smell? That question has remained unanswered, until now, in part due to such technical difficulties as getting the intensities of all the scents to be identical.
A research team in the Neurobiology Department, led by research student Tali Weiss and Dr. Kobi Snitz, both in the group of Prof. Noam Sobel, [2] decided to take up the challenge. They began with 86 different pure scents (each made of a single type of odor molecule) spanning the entire “smell map,” diluted them to obtain similar intensities and then created blends. Each blend contained a different mixture of odors from various parts of the smell map. These blends were then presented in pairs to volunteers, who were asked to compare the two scent-blends.
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The team discovered that the more odors that were blended together in the paired mixtures, the more the subjects tended to rate them as similar – even though the two shared no common components. Blends that each contained 30 different odors or more were thought to be almost identical.
The researchers then created a number of such odor blends, giving them a nonsense name: Laurax. Once the subjects were exposed to one of the Laurax mixes and became accustomed to the smell, they were exposed to new blends – mixtures they had not previously smelled. They also called some of these new blends &