Page 51 - Fall 2006

Acoustics in the news
􏰀 Researchers at the University of Illinois and the University of Missouri-Rolla have built an ultrasound version of a laser, according to a story in the June 12 issue of NASA Tech Briefs. Called a uaser (pronounced WAY-ser for ultrasound amplifi- cation by stimulated emission of radiation), the instrument produces ultrasonic waves that are coherent and of one fre- quency. The device consists of piezoelectric auto-oscillators mounted on a block of aluminum, which serves as an elastic acoustic resonator. When an external acoustic source is applied, the oscillators synchronize to the frequency of the source. The device demonstrates, according to the inventors, that “the essential nature of a laser can be mimicked by clas- sical mechanics–not quantum mechanics–in sound instead of light.”
􏰀 It is now possible to hear what the voice of the Mona Lisa would have sounded like, according to a story in CNN.com dated June 2. The chart of any individual’s voice, known as a voice print, is unique to that person, and a Japanese researcher believes he has achieved 90 percent accuracy in recreating the quality of the enigmatic woman’s speaking tone. In the Mona Lisa’s case, the lower part of her face is quite wide (which suggests a low voice) and her chin is pointed (which adds tones in mid-frequency).
􏰀 When it came out in December, the high-frequency sound of a device called Mosquito was supposed to be the sonic equivalent of a “no loitering” sign (see Acoustics in the News in the summer issue of ECHOES). Its annoying sound, which many adults can’t hear but most young people can, would act as a teen repellent. Now, according to a story in the June 14 issue of The Washington Post, teens are getting back at adults. Downloading the sound, or another ring tone in the same frequency range (around 17 kHz), allows them to hear their cellphones ring when their parents and teachers cannot. Traffic at one website which markets the tone, spiked as 100,000 kids tried to download the sound.
􏰀 “Balancing the art and science of sound” is the title of an article in the advertising supplement to the June 14 edition of International Herald Tribune that deals with opera houses. “It’s a myth that there’s a perfect acoustics” is a statement by an opera conductor with which many acousticians would agree. However, the definition of acoustics as “basically air vibrating in a cavity” is one with which there would be less agreement.
􏰀 Last year, according to the 11 July issue of the Institute, more than 1500 people joined the IEEE Women in Engineering (WIE) group, the largest annual growth in its history, bringing the total number of WIE members to about 12 000. Last year also saw the formation of 43 WIE Affinity Groups and Student Affinity Groups, the most ever estab- lished in one year, for a total of 103. Student IEEE member- ship increased by more than 8% last year, while membership in regular grades increased only 0.5%.
􏰀 Scientists at the University of Tromso in Norway are inves- tigating the “strange musical sounds” practiced by violinist
Mari Kimura, according to a story in the 6 July issue of the World Science home page. ASA members may recall that Roger Hanson and Fred Halgedahl explained these “anom- alous low frequency” (ALF) violin sounds some 15 years ago, and Mari demonstrated them at an ASA meeting.
􏰀 A $30 million Air Force memorial just west of the Pentagon which reaches 300 feet into the air required a spe- cial vibration damper, according to a story in the 17 July issue of the Washington Post. Early in the design process, wind-tunnel tests revealed that the wind could send the silver spires into a series of oscillations that could lead to cata- strophic failure. The solution involved an exotic trick of physics. Hidden high inside the elegant metallic spires designed by James Ingo Freed, who also designed Washington’s Holocaust Museum, are 13 steel boxes, a stack of six in the tallest spire, four in the next and three in the last, which, although it is the shortest, still rises 201 feet above the ground. The boxes are about 2 1/2 feet on each side, and each contains a single, free-rolling, metal ball that is 20 inch- es in diameter and weighs nearly a ton. Those balls in boxes provide a unique energy-damping system that, although invisible to visitors, promises to keep the monument's sway- ing within tolerable limits well into the 22nd century.
􏰀 Although the world seems to get noisier all the time, the hearing of Americans is not worse today than it was 35 years ago, according to a government study reported in the 30 June issue of Science. The study of some 5000 subjects reports that blacks have better hearing than whites, and women hear better than men.
􏰀 A dark horse has jumped into the race to solve the mystery of dark energy, according to a story in the August 12 issue of New Scientist. NASA has decided to fund the ADEPT probe, which will probe this unknown force by looking for the imprint of primordial sound waves. Until now, the front run- ners were missions that planned to study dark energy by looking for ancient supernovae, which is hardly surprising, since it was the study of supernovae in the 1990s that led to the discovery of dark energy. The ADEPT (Advanced Dark Energy Physics Telescope) probe, however, will look for sound waves that permeated the infant cosmos and helped to trigger the formation of galaxies. Astronomers have noted a repeating pattern of slight excesses of galaxies in the cosmos having a wavelength of a few 100 million light years.
􏰀 It’s a myth that there is a perfect acoustic,” Kent Nagano, the new music director at Munich’s Bayerische Staatsoper, is quoted as saying in the June 14 issue of the International Herald Tribune. Nagano, who succeeded Zubin Mehta, con- siders the Munich opera house to be “fantastic” for opera but not for symphonic concerts. When the orchestra leaves the pit to go onstage a specially designed acoustic shell is employed. Nagano says that the only way to know what the audience hears is by going into the seats oneself.
􏰀 Wavelets are being used to transform the haunting calls of whales into movies, according to a story in the August 1
Excerpts from Echoes 49