The Palm Beach Post: Very unscientific measure finds train horn levels higher than reported

Posted on April 13, 2015

The Federal Railroad Administration reported this past week that new locomotives running on the Florida East Coast Railway tracks are sounding at 103.6 decibel levels — louder than a jet flyover at 1,000 feet, but quieter than a riveting machine up close.


With a federal mandate that train horns range between 96 decibels at 110 decibels, FECR’s engine horns are well within required levels. But making a comparison is difficult because neither the Federal Railroad Administration or Florida East Coast Railway will release the decibel level produced by the old locomotive horns.


Residents who live along the FEC line say without a doubt the horns are louder. Whether it’s a difference in frequency or the number of chimes — reasons given by the railroad for the perception that the horns are louder — residents say noise they once slept through now wakes them at night.


“I can’t think it’s an aberration when we have hundreds of people up and down the corridor saying the horns are louder,” said Brent Hanlon, general manager of Hobe Sound’s Loblolly community, which is adjacent to the FEC tracks. “People are not making this up.”


Sound experts consulted by The Palm Beach Post said the smallest incremental change a human ear can hear is three decibels, while an increase of five decibels would be classified as “clearly audible.”


Mark Sheplak, a University of Florida professor of electrical and computer engineering who specializes in acoustics, said a six-decibel level increase is a doubling of the sound.


“Depending on the frequency, the threshold of pain is 120 decibels, so you are marching closer to that at 103.6,” Sheplak said.


The Palm Beach Post conducted its own very unscientific decibel level measure of various environmental noises with a $40 device purchased at a local electronics store. The loudest measures came from the horns of passing Florida East Coast Railway trains. Two passes by the new locomotives registered 106 decibels and 108 decibels at their peaks. One of the old locomotives topped out at 106 decibels.


Airplane noise just east of Interstate 95 under the flight path of Palm Beach International Airport registered between 82 and 85 decibels, while the highest traffic noise reading was a passing cement truck at 83 decibels.


Experts caution that a $40 decibel level reader taking measurements without proper controls or consideration for variables such as wind and building echoes is likely inaccurate.


“The equipment we use ranges in price from $8,000 to $12,000,” said Keely Siebein, a consultant with Gainesville-based Siebein Associates Architectural and Environmental Acoustics. “Keep in mind train horns are designed so the guy in his car with the windows up, the air conditioning on and the music blaring, will hear them.”


Also, Siebein said a change in noise level may be noticeable at first, but that people usually adjust.

“A change in noise happens and everyone is up in arms, but after a while people do habituate,” Siebein said.

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