Because of the distance that low-frequency sound waves can travel under water, a set of four ships emitting sound at 235 decibels could monitor 80% of the world's oceans for submarines.
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Soil is a highly attenuating material, meaning that it is difficult for sound waves to travel far in it.
Throughout its life Amtrak has made the argument, repeatedly, that rail is the most cost-effective and environmentally sound form of travel.
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"Inside stars it's a very noisy environment, and that noise sets up sound waves that travel all the way through the star, " said Birmingham astrophysicist Prof Yvonne Elsworth.
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The NOAA ship Okeanos Explorer mapped the locations between Nov. 2 and Nov. 20 using multibeam sonar, which produces detailed images of the seafloor by calculating the amount of time and distance it takes for sound waves to travel from the ship to the seafloor and back.
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The doctor does not mean to sound alarmist about air travel.
It takes only a few minutes, and it gives you an opportunity to sound off about the Asia travel experiences you deem best--and worst.
These waves travel at the speed of sound, but when a jet travels at Mach 1 and above these waves merge into one single shock wave as they cannot get out of the way of each other quickly enough.
NASA, America's space agency, is paying for an experimental version of Inductrack that will travel at half the speed of sound.
Viewing the Atlantis orbiter perched on the launch pad and protected by the service structure made it seem very fragile, even though it was made to travel over 100 times the speed of sound.
However, the sound waves themselves become attenuated in different ways as they travel through different people.
After a couple of days spent chugging through the landscapes of the Old West, the well-worn travel adage about the journey being as important as the destination starts to sound a lot less trite.
They need to travel to interview people all over the country, pay for archival footage, add sound, music and graphics, and complete a thousand other small but costly tasks.
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