Listening to iPods at ”jet” volume can make you deaf

April 21, 2010 By Leave a Comment

London, Apr 21 (ANI): Listening to personal music players for several hours a day at high volume could put your hearing at risk, an expert has warned.

Writing in the British Medical Journal, Professor Peter Rabinowitz from Yale University School of Medicine said that personal music devices such as MP3 players and iPods can generate levels of sound at the ear in excess of 120 decibels, similar in intensity to a jet engine, especially when used with earphones that insert into the ear canal.

According to the expert, the use of such devices is high in young people and “has grown faster than our ability to assess their potential health consequences.”

“Personal music players provide a reminder that our hunger for new technology should be accompanied by equally vigorous efforts to understand and manage the health consequences of changing lifestyles,” he concluded. (ANI)

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Invading black holes cause ‘cosmic flashes’

September 19, 2009 By Leave a Comment

Washington, September 19 (ANI): Mathematicians at the University of Leeds, UK, have determined that cosmic flashes, known as gamma ray bursts, are produced by jets of plasma that originate from invading black holes.

Gamma ray bursts are beams of high-energy radiation that are similar to the radiation emitted by explosions of nuclear weapons.

The orthodox model for this cosmic jet engine involves plasma being heated by neutrinos in a disk of matter that forms around a black hole, which is created when a star collapses.

But, mathematicians at the University of Leeds, have come up with a different explanation: the jets come directly from black holes, which can dive into nearby massive stars and devour them.

Their theory is based on recent observations by the Swift satellite, which indicates that the central jet engine operates for up to 10,000 seconds – much longer than the neutrino model can explain.

Mathematicians believe that this is evidence for an electromagnetic origin of the jets, that is, that the jets come directly from a rotating black hole, and that it is the magnetic stresses caused by the rotation that focus and accelerate the jet’s flow.

For the mechanism to operate, the collapsing star has to be rotating extremely rapidly.

This increases the duration of the star’s collapse as the gravity is opposed by strong centrifugal forces.

One particularly peculiar way of creating the right conditions involves not a collapsing star, but a star invaded by its black hole companion in a binary system.

The black hole acts like a parasite, diving into the normal star, spinning it with gravitational forces on its way to the star’s centre, and finally eating it from the inside.

“The neutrino model cannot explain very long gamma ray bursts and the Swift observations, as the rate at which the black hole swallows the star becomes rather low quite quickly, rendering the neutrino mechanism inefficient, but the magnetic mechanism can,” said Professor Komissarov from the School of Mathematics at the University of Leeds.

“Our knowledge of the amount of the matter that collects around the black hole and the rotation speed of the star allow us to calculate how long these long flashes will be – and the results correlate very well with observations from satellites,” he added. (ANI)

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Exploding volcanoes make noise similar to jet engines

April 9, 2009 By Leave a Comment

Washington, April 9 (ANI): In a new research, scientists have suggested that the large-amplitude signals from volcanic eruptions are similar to the noise produced by typical jet engines.

The research was done by scientists from Scripps Institution of Oceanography at UC (University of California) San Diego.

The research team speeded up the recorded sounds from two volcanoes and uncovered a noise very similar to typical jet engines.

These new research findings provide scientists with a more useful probe of the inner workings of volcanic eruptions.

Infrasound is sound that is lower in frequency than 20 cycles per second, below the limit of human hearing.

The study, led by Robin Matoza, a graduate student at Scripps Oceanography, measured infrasonic sound from Mount St. Helens in Washington State and Tungurahua volcano in Ecuador, both of which are highly active volcanoes close to large population centers.

“We hypothesized that these very large natural volcanic jets were making very low frequency jet noise,” said Matoza, who conducts research in the Scripps Laboratory for Atmospheric Acoustics.

Using 100-meter aperture arrays of microbarometers, similar to weather barometers but sensitive to smaller changes in atmospheric pressure and low-frequency infrasonic microphones, the research team tested the hypothesis, revealing the physics of how the large-amplitude signals from eruptions are produced.

Jet noise is generated by the turbulent flow of air out of a jet engine.

Matoza and colleagues recorded these very large-amplitude infrasonic signals during the times when ash-laden gas was being ejected from the volcano.

The study concluded that these large-scale volcanic jets are producing sound in a similar way to smaller-scale man-made jets.

According to Michael Hedlin, director of Scripps’ Atmospheric Acoustics Lab and a co-author on the research paper, “We can draw on this area of research to speed up our own study of volcanoes for both basic research interests, to provide a deeper understanding of eruptions, and for practical purposes, to determine which eruptions are likely ash-free and therefore less of a threat and which are loaded with ash.”

Researchers also hope this new information can improve hazard mitigation and inform pilots and the aviation industry. (ANI)

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