Before this set of experiments, the scientists conducted tests that proved blindfolded listeners could accurately describe the shape of foam core objects blocking speakers emitting sound. They could also determine the width and size of a changeable doorway-like frame when sounds from built-in speakers came out of it. Although people are not always conscious of reflected and ambient sound, our brains are always processing such information. "For example, we take into account an individual's distance and surroundings based on reflections as we process their voice," Rosenblum said. "We do the same when we are determining the simple position of a sound source." Another team led by Osaka University's Takahisa Furukawa will announce at the Paris meeting that detection of background noise appears to be affected by genetic or cultural differences. Furukawa and his colleagues discovered Japanese, American and German people in an office setting heard background noises -- in this case, the sound of a copy machine -- differently, although all listeners were annoyed by the machine. Japanese participants complained of the "impulsiveness" of the sound, while the American and Germans found it to be too "sharp." In another related study, published in Physical Review Letters, University of Illinois at Urbana-Champaign researchers found that silent objects really do emit noise at the nano level. Using special equipment, they picked up tiny vibrations of thermal energy that exist naturally in all objects, alive or not. The resulting mini-sound waves were named phonons. Richard Weaver, a professor of theoretical and applied mechanics at UI, described them as being "like BBs rattling inside a box" that bounce off the object's walls. In the future, detection of phonons could be used to identify random vibrations from distant earthquakes, Weaver said. Related Links: |
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