Reading 1

Unit 5- Reading 1

Page 66

Virtual odors?

Movies have successfully captured sights and sounds on film since the 1920s. And today we can enjoy realistic and imaginary multimedia delights even on hand-held devices.

But if such treats for the eye and ear are now commonplace, why is there no machine that can readily incorporate our sense of smell into the experience of a movie or a video game?

Actually, movie makers have tried to add this missing dimension. In 1959, a film called Behind the Great Wall piped odors through the air-conditioning system of a theater.

The I960 film Scent of a Mystery, featuring Smell-0-Vision, opened in a theater equipped to release smells in synch with the movie. Director John Waters gave “scratch-and-sniff cards out to accompany his “Odorama” movie Polyester (1982). And Wait Disney World’s Epcot theme park near Orlando, Florida uses odors to enhance its Journey into the Imagination attraction.

So far, though, Smell-0-Vision-type devices are no more than gimmicks of only marginal interest. Why? No affordable machine can store enough odors to simulate more than a small fraction of what humans can smell.

Sound and color simulation do not face such limitations. Computer monitors, for example, can recreate millions of colors because it really only takes three colors to do so.

A screen that can display tiny red, green, and blue pixels can combine these colors to reproduce most colors that a human eye can see. Sound waves, though quite complex, can be defined mathematically, reproduced by a synthesizer, and amplified electronically.

Odors are different. They cannot be manipulated or defined mathematically. As Jaron Lanier explains in an article in New Scientist.

odors “are not patterns of energy, like images or sounds. To smell an apple, you breathe hundreds or thousands of apple molecules into your nose.” There is no way to amplify them other than adding more odor molecules. Plus, each molecule that triggers smell is unique. This means a machine cannot produce all possible odors by simply mixing three odors.

It is true that odor-causing chemicals can be combined to produce millions of scents, but the minimum number of basic odors required would be in the many hundreds, perhaps thousands, to simulate all the scents that humans can sense.

Several odor parameters can be identified that might be useful. We can talk about the intensity of an odor or the persistence of an odor.

We can label it as pleasant or unpleasant. Non-offensive odors can be grouped into seven general categories: medicinal, floral, chemical, fruity, vegetable, fishy, and earthy. They can also be categorized by how they feel in our nose: tingly, burning, warm, metallic, pungent, itching, sharp, and cool.

But there are simply too many odors in each category to design a practical device that could reference and recreate all the scents we can smell. Jaron Lanier says, “Colors and sounds can be measured with rulers, but odors must be looked up in a dictionary.”

That dictionary is in the brain.

Odors are detected deep in the nasal passage when molecules come into contact with the olfactory epithelium—a patch of tissue covered with neurons. These neurons have receptors3 that can detect a particular molecule. If a molecule fits into a matching receptor, the brain gets a signal. Apparently, the human nose has about one thousand different types of olfactory neurons.

The brain’s “smell dictionary” categorizes odors, but not in a way that a chemistry book would. Instead the brain groups smells according to what they mean in the real world. Things that emit a rotting smell, for example, get very special handling. Interpreting smell also requires help from the other senses, and its meaning may derive from the context.

Whether a smell is good or bad may depend on where you smell it and what you think is causing it. If a bowl of ice cream smells like hard-boiled eggs, you probably won’t eat it even if you like hard-boiled eggs. In other words, smells function a bit like words do.

We know thousands of different words, and the meaning of a word depends on the context in which it occurs. We define a word by pointing to the entity it refers to or by comparing its meaning to other words. With scents, we may say “it smells like a cucumber” or “it has a soapy smell.”

If millions of visible colors can be produced from just three primary colors, is there any hope of finding smell “pixels” that will trigger the perception of smell in our brains? We, of course, see images on computer screens that look real to us even though the objects are not really there. They are optical illusions.

Likewise, sound recordings and even your cell phone create an auditory illusion—the source of the original sound only seems to be present. Is it possible to design a mechanism that could somehow manipulate our brain to create the illusion of smell when no odor molecules are present— virtual odors?

In the near future, this achievement seems remote, but some progress is being made in research on machines that can mimic the sense of smell. These “electric noses” are equipped with olfactory sensors that detect specific odors. In order to design such a machine, scientists and engineers must be able to classify and identify an odor’s distinctive “fingerprint” and design a mechanism that can electronically detect that fingerprint.

The possible value of such a machine in food inspection, medicine, and law enforcement has prompted several dozen companies to develop and sell electronic nose units.

If a machine can digitally detect odors, perhaps the reverse is possible. The Tokyo Institute of Technology is reported to be working on an odor recorder and generator.

The plan is to design a gadget that can be pointed at an object, record its odor through 15 electronic noses, and recreate the odor by mixing together and vaporizing odors from a set of 96 nontoxic chemicals. If this device succeeds, it will move well beyond current odor generators. These emit only a small number of odors and have failed commercially.

If odor recorders and generators prove to be feasible and affordable, Smell-O-Vision may be primed for a comeback, adding a new dimension to the moviegoing experience. It may even require a new film rating system: “Warning: This movie is rated R for Rotten. Contains odors (hat some may find offensive.”