THE CUTTING EDGE: COMPUTING / TECHNOLOGY / INNOVATION : Listen Up: That Really <i> Is</i> a Ringing Sound

That occasional annoying ringing in the ear, common to half the adult population, is an actual sound. It can even be recorded by a tiny microphone planted in the ear canal, because it is created by the ear itself. The ringing or whistling is the result of amplification of a wave in the fluid of the inner ear and is associated with certain mild cases of tinnitus.

Now a researcher at Los Alamos National Laboratory has described these waves, explaining why, under certain circumstances, the ear whistles. Physicist George Zweig built on his 1975 discovery of the continuous wavelet transform, a mathematical method of describing sound waves that is now widely used to remove “noise” from many different kinds of sound. Explaining why ears ring could open new directions in acoustic research, and that in turn could lead to better hearing aids, improvements in the technology of cochlear implants and further development of speech-recognition machines.

The ear can amplify faint sound waves generated by soft noises and send this information to the middle ear, where it is then sent to the inner ear. But wave energy not transferred to the middle ear is reflected again and amplified again, setting up a resonance in the fluid-filled tubes of the cochlea. If the process runs away with itself, the ear begins to whistle spontaneously. A better understanding of how the ear responds to the broad dynamic range of sound it naturally encounters should help improve cochlear implants, which substitute electrical stimulation of the ear for the lack of inner hair cells that is often associated with deafness.

*

Wisdom of Bees: People who possess a lot of common sense are often said to have “horse sense.” But new research into how bees forage for nectar in a field of flowers suggests that having “bee sense” might be a higher accolade.

In a study published in a recent issue of Nature, a team that included a researcher from the Howard Hughes Medical Institute at UC San Diego described how they combined computer theory and computer simulations to create a “virtual bee” capable of flying from flower to flower in search of nectar.

In the past, how a bee decides to land on a given flower was thought to be the result of some strategic thinking mechanism or sophisticated calculation. But the virtual bees, constructed of neural networks and an algorithm that enabled them to learn from experience, suggest that a system based on a set of neurons found in the brain are designed to help the bee make quick decisions--better known as common sense.

With the help of the neural net and a simple guidance system that simulated bee eyes, the bees were set free onto a three-dimensional simulated field of yellow and blue flowers. Flower color was the only predictor of how much nectar a bee might receive. In most cases, the bees learned to fly to the color that contained the most nectar, even when the colors were switched.

The research could help those interested in artificial intelligence. Thus far, scientists have been able to design machines that solve complex problems of logic, problems that humans also find difficult. But things that humans generally take for granted, such as seeing and rendering judgment, have confounded the fastest and most powerful computers. Virtual bees seem to offer a clue as to how nature solves this problem.

*

Less Smoke in Air: Smoke is a major cause of injuries and deaths in airplane crashes--which is why the Federal Aviation Administration has awarded Case Western Reserve University $1.92 million over five years to continue research on a new plastic that burns more slowly and emits less gas, providing passengers with extra time to escape an airplane following an accident.

Preliminary tests show that only 15% of the new material, polybenzoxazine, burns or goes up in smoke, compared to half to nearly three-quarters of other fire-resistant plastics--called phenolic resins--that were first synthesized around the turn the century.

The new material can be produced from abundant, low-cost raw materials and appears flexible enough to be used in a wide range of molded parts, including computer housings. Such a broad range of applications should lower production costs. The FAA funds will be used to study how plastics burn and what is happening inside the molecules.

Schneller Inc., a Kent, Ohio, manufacturer of decorative plastic laminates for aircraft interiors, has been conducting additional tests on the new plastic. It could be in use within the next five years if the material is available in commercial quantities from two reliable sources and meets aircraft manufacturers’ specifications.

*

Supercritical Solvents: A process currently used to decaffeinate coffee may also be useful in removing organic waste from soil, according to researchers at Ohio State University, the University of New South Wales in Australia and the Georgia Institute of Technology.

Manufacturers now use a “supercritical” fluid to remove caffeine from coffee beans. A supercritical fluid is created when the pressure and temperature of a compound are increased beyond the “critical point,” where gas and liquid physical states can no longer coexist. At this point, the compound is in a single state and will not boil or condense; it becomes a solvent capable of dissolving organic materials.

But instead of caffeine, the researchers are looking at how well supercritical carbon dioxide could dissolve different types of organic waste in soil. One study found that carbon dioxide was capable of removing almost 60% of DDT from a sample of activated carbon, a common charcoal absorbent that acts as a model for soil.

While the use of supercritical fluids has been studied since the late 1970s, the high cost of building a pressure vessel has prevented its use in environmental cleanup. But David Tomasko, an assistant professor of chemical engineering at Ohio State, says the operating cost of using carbon dioxide is competitive with other contaminant removal technologies and that he is looking at ways to make the technology even more cost-efficient. Tomasko is also looking at the potential use of supercritical fluids as a replacement for toxic organic solvents used by companies that manufacture products such as pharmaceuticals.