Neither pleasant nor foul-smelling, and in no way overwhelming: this is how researchers sum up the smell they are calling “olfactory white”.
The smell was uncovered during experiments that mixed aroma molecules from across the scent spectrum. Even if two mixtures had no components in common, they tended towards having a similar scent as more aromas were added. By the time they contained about 30 components, most mixtures smelled alike1, and could mask other distinctive smells.
The researchers say that the resulting smell, which is unlikely to occur naturally, has parallels with both white light and ‘white noise’. These are produced by combining the wavelengths of the visible spectrum and different sound frequencies, respectively.
Given that our noses contain hundreds of different odor receptors, the phenomenon is counterintuitive, says Noam Sobel, an neuroscientist at the Weizmann Institute of Science in Rehovot, Israel, who led the work, published today in the Proceedings of the National Academy of Sciences. “One might imagine that the more odors are added, the more ‘special’ the odor would become,” he says, “Yet what we show is the opposite.”