European Stars And Stripes (Newspaper) - July 12, 1986, Darmstadt, Hesse                                R v. ". A scientist hat discovered that the accepted Speed of found of 7415 Miles per hour it Moscak United. Slowing Down the Speed of sound a photo by James Gleick new York times a Canadian scientist has discovered thai the Speed of sound in air is nearly a hair Mil per hour slower than physicists acoustic ans and aerodynamic engineers have thought for four decades. The finding confirmed by acoustic ans who have studied it. Reveals a Small but significant error in modern calculations of one of nature s most venerable benchmarks when Charles e. Yeager smashed the sound Barrier in 1947 and the concorde made it a relic of history the Speed of sound was put at 741.5 Miles per hour or 331.45 meters per second. That is the figure Given by the Standard handbooks and textbooks and used for a wide assortment of engineering calculations no one had reason to doubt it. But in the course of trying to calibrate microphones As accurately As possible. Or George . Wong a senior research officer of the National research Council of Canada discovered that the old figure was off. With the help of refined instrumentation and what he called a year and a half of detective work he produced a figure that was slightly but significantly slower 741.1 Miles per hour or 331.29 meters per second Wong said that he had uncovered a 1942 calculation error that steadily  its Way through the scientific literature never challenged. It s quite a Surprise he said. Everybody thought that thing was closed in died years  apart from its role in the folklore of , the Speed of sound in air is a Basic constant in the science of acoustics. It helps to determine the Way aircraft and projectiles move through the atmosphere the Way sound Waves reverberate in different rooms and the Way gases move at High pressure through pipelines. For theorists the Speed of sound and related quantities provide a Bridge Between substances behaviour at molecular Scales and at Large Scales. It s a very fundamental Quantity when it comes to the flow and movement of gases As fundamental a constant for acoustics As the velocity of Light is for optics said Robert d. Finch of the University of Houston a specialist in engineering acoustics. All sorts of calculations use the Speed of sound in Page 16 the stars and stripes air. It s so fundamental that it s hard to avoid " in practice engineering problems that rely on the Speed of sound from the reverberation time of concert Halls to the Onset of turbulence in air Rushing Over an air plane Wing usually have too much built in imprecision to be affected by a refinement As Small As Wong s. His figure applies to dry air at 0 degrees centigrade and at Standard atmospheric pressure at sea level. Outside a Laboratory the vagaries of temperature humidity air pressure and even the composition of air can All raise or lower the effective Speed of sound by Many Miles an hour still some acoustics specialists suggested that As a precise Benchmark Wong s result might help in he calibration of scientific instruments such As micrometers that use the Speed of sound to measure distances to within a thousandth of an Inch. The finding May be just a nuance but it is a nuance with Pedigree. A refinement in the Speed of sound or he Speed of Light or anything that fundamental is not trivial said Daniel w. Martin editor in chief of the journal of the acoustical society of America which published Wong s findings in its May Issue. Other acoustic ans who have examined Wong s technique said that the calculations were careful and methodologically sound. The Fine tuning of standards like the Speed of sound is a habitual Pursuit of scientists an activity that combines scientific gamesmanship with the obsessive Pursuit of perfection. In a wide Range of materials the Speed of sound gives a clue to other important properties. Because it depends on the Basic molecular Spring Ness and density of a substance it provides a tool for exploration. We might measure sound Speed in rubber or plastic or some composite because we want to know How material will behave when put into some sort of system or device said Anthony Rudgers a research physicist at the United states naval research Laboratory. And at the National Bureau of standards the american equivalent of Canada s research Council researchers Are using Speed of sound measurements in purer gases As a Way of determining quantities of More theoretical interest to physicists such As the Universal Gas constant a basis for understanding the general properties of gases. Saturday july 12,1986 the Speed of sound in air is a dirtier problem since it depends on defining a Standard air with appropriate proportions of nitrogen oxygen Carbon dioxide and other gases. There never is Standard air " said Michael r. Moldover of the National Bureau of standards. It s a notorious problem. Ultimately your understanding proceeds to the Point where you can calculate something better than you can measure  a reliable figure for the Speed of sound has been a scientific Quarry since Newton s Era when experimenters would stand on hilltops and measure the time Between the Flash of a Musket Miles away and the arrival of the report. This was Virgin territory for theorists and they struggled with the most Basic questions did it matter which Way the wind was blowing did it matter which Way the Musket was fired and did it matter whether the sound travelled downhill the answers were yes no and no Newton himself in the first edition of the principle mathematics gave a detailed explanation of sound vibrations travelling through various substances in the form of Waves but his calculation of the Speed of sound in air was wrong by More than 15 percent. Lacking Good experimental evidence he presumed incorrectly that sound Waves As they travel through a Gas would not produce temperature fluctuations As the wests and troughs went by. In fact they do and that affects the Speed of the wave. Wong took up the Speed of sound problem As a sideline at Canada s National research Council where he was primarily concerned with standards that required Fine calibration of microphones. The Council s principal research officer for acoustics Tony Embleton said such work was essential for the Sake of Industry. To maintain consistent standards across National Borders for example laboratories Swap actual microphones after calibrating them. People must have Confidence that our 90 decibels n Canada Are the same As 90 decibels in the United states or any other country he said. To make is calibrations As precise As possible Wong needed a precise value for the specific heat of air the amount of heat needed to raise the temperature by a Given amount. He found that the figures available did not take into account humidity s effect so he began to derive new figures