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Tornado Sirens, an Old Technology, Still Play a Vital Role Tornado Sirens, an Old Technology, Still Play a Vital Role
(about 5 hours later)
For residents of tornado-prone regions like Oklahoma, Texas and the southern Plains, the piercing wail of outdoor sirens in May — the most active month — is a warning to seek shelter because a funnel cloud has been spotted or is on its way.For residents of tornado-prone regions like Oklahoma, Texas and the southern Plains, the piercing wail of outdoor sirens in May — the most active month — is a warning to seek shelter because a funnel cloud has been spotted or is on its way.
In an age of text alerts, social media and smartphones, you might think sirens had outlived their usefulness in alerting the public to approaching severe weather.In an age of text alerts, social media and smartphones, you might think sirens had outlived their usefulness in alerting the public to approaching severe weather.
But officials and enthusiasts believe they continue to serve a vital role in public safety.But officials and enthusiasts believe they continue to serve a vital role in public safety.
Logan Shelts, the lead moderator of Air Raid Sirens, an online forum of educators and enthusiasts, said tornado sirens were an outgrowth of the Cold War, when they were installed to alert communities in case of a nuclear attack or an air raid.Logan Shelts, the lead moderator of Air Raid Sirens, an online forum of educators and enthusiasts, said tornado sirens were an outgrowth of the Cold War, when they were installed to alert communities in case of a nuclear attack or an air raid.
Sirens were first used to warn of tornadoes in 1970. That was a big improvement from alerts in times gone by.Sirens were first used to warn of tornadoes in 1970. That was a big improvement from alerts in times gone by.
Plans from the 1800s called for telegraph wires that could snap in high winds, triggering alarm bells and firing a cannon, according to a journal published by the American Meteorological Society.Plans from the 1800s called for telegraph wires that could snap in high winds, triggering alarm bells and firing a cannon, according to a journal published by the American Meteorological Society.
Despite advancements in meteorology, a ban on tornado warnings lasted from 1887 until 1938 because researchers believed they would promote panic, the article noted. Even the use of the word “tornado” in forecasts was discouraged until 1950, when the Weather Bureau officially changed its policy.Despite advancements in meteorology, a ban on tornado warnings lasted from 1887 until 1938 because researchers believed they would promote panic, the article noted. Even the use of the word “tornado” in forecasts was discouraged until 1950, when the Weather Bureau officially changed its policy.
Generally, they can be heard within one mile, but their reach varies by their size and the topography, atmospheric conditions and seasons, said Aaron Wolking, a national sales manager with Sentry Siren in Canon City, Colo.Generally, they can be heard within one mile, but their reach varies by their size and the topography, atmospheric conditions and seasons, said Aaron Wolking, a national sales manager with Sentry Siren in Canon City, Colo.
Larger sirens have a two-mile radius. Sirens should register 70 decibels from 100 feet away, according to a minimum set by the federal authorities, Mr. Wolking said. The company’s largest siren can put out 130 decibels. Larger sirens have a two-mile radius. How do federal authorities determine how loud a siren should be? An effective range is calculated by measuring its decibel output at 100 feet and then applying a formula developed by federal authorities that accounts for how sound waves fade over a given distance, Mr. Wolking said. The company’s largest siren can put out 130 decibels.
The loudness and pitch of sirens “exploit basic principles of human audition to signal danger,” Elizabeth Hellmuth Margulis, a professor of music and the director of the Music Cognition Lab at the University of Arkansas, said in an email.The loudness and pitch of sirens “exploit basic principles of human audition to signal danger,” Elizabeth Hellmuth Margulis, a professor of music and the director of the Music Cognition Lab at the University of Arkansas, said in an email.
In addition, sound is “especially good at carrying emotional resonance,” so the tone you heard as a child during drills will prompt “deep and immediate” feelings later in life, she said.In addition, sound is “especially good at carrying emotional resonance,” so the tone you heard as a child during drills will prompt “deep and immediate” feelings later in life, she said.
Most sirens emit sounds between 400 and 600 hertz, which researchers have found is the best range to get people’s attention, said Scott Yarberry, the chief operating officer and executive vice president of Sentry Siren.Most sirens emit sounds between 400 and 600 hertz, which researchers have found is the best range to get people’s attention, said Scott Yarberry, the chief operating officer and executive vice president of Sentry Siren.
There are mechanical sirens:There are mechanical sirens:
There are electronic sirens:There are electronic sirens:
Sirens can put out an “alert” tone — a three-minute, uninterrupted sound — or an “attack” tone that modulates and sounds like a classic air-raid siren.Sirens can put out an “alert” tone — a three-minute, uninterrupted sound — or an “attack” tone that modulates and sounds like a classic air-raid siren.
Some sirens are stationary, and others rotate; they also come in a variety of shapes and sizes. Some are dual tone, meaning they produce two pitches at once.Some sirens are stationary, and others rotate; they also come in a variety of shapes and sizes. Some are dual tone, meaning they produce two pitches at once.
For out-of-the-way places, such as golf courses, lakes and hiking trails, where cellphone service might be spotty or nonexistent, sirens are an “important redundancy” to alert the public, said Bill Bunting, the chief of forecast operations at the Storm Prediction Center in Norman, Okla.For out-of-the-way places, such as golf courses, lakes and hiking trails, where cellphone service might be spotty or nonexistent, sirens are an “important redundancy” to alert the public, said Bill Bunting, the chief of forecast operations at the Storm Prediction Center in Norman, Okla.
Mr. Shelts said social media can be ineffective in delivering warnings because there is no true management or vetting of what gets posted. Incomplete, inaccurate or outdated information could be shared.Mr. Shelts said social media can be ineffective in delivering warnings because there is no true management or vetting of what gets posted. Incomplete, inaccurate or outdated information could be shared.
Sirens also hold up well: One unit that Sentry Siren installed in Maryland has been in continuous service since the 1920s, Mr. Yarberry said.Sirens also hold up well: One unit that Sentry Siren installed in Maryland has been in continuous service since the 1920s, Mr. Yarberry said.
Fire departments use them to summon volunteers, and some communities use them to warn of the threat of large hail or powerful winds.Fire departments use them to summon volunteers, and some communities use them to warn of the threat of large hail or powerful winds.
Yeshiva Toras Emes Kamenitz in Brooklyn uses Sentry Siren’s largest siren, a model 40V2T with a two-mile radius, to sound the start of the Sabbath, Mr. Yarberry said.Yeshiva Toras Emes Kamenitz in Brooklyn uses Sentry Siren’s largest siren, a model 40V2T with a two-mile radius, to sound the start of the Sabbath, Mr. Yarberry said.