If you're ever in Williamsburg ten minutes before the sun sets on a Friday night, you'll have heard the eerie sirens that wail far and wide throughout the neighborhood. It isn't a test or drill, it's the warning that Shabbat will be starting soon, and it's time to go home (if you're Orthodox Jewish).

It's not just one siren, but several, installed on different Yeshivas in South Williamsburg, a neighborhood that's predominantly ultra-Orthodox Jewish. The sirens are controlled independently, which is why they can sound overlapped and echoed. The Torah says that the start of Shabbat is announced with the blowing of a "shofar," a ram's horn. The noises you hear are from STH-10 model mechanical sirens... close enough. I found two of them: one on 152 Rodney Street and one on 163 Clymer Street, and was surprised at how far south they were. They're easily heard as far up as Greenpoint.

These things are loud . In 2004, a Yeshiva in Midwood, on Avenue N, received five noise code violations from the Environmental Protection Department for their siren, the Daily News reported. Technically, the city exempts religious institutions from this code, but neighbors complained that the volume was too extreme. The noise decibel level accepted by the city is 45 decibels, and the yeshiva's siren was at 127. In the end, they agreed to lower it. In particular, war veterans were most agitated by the noise, which reminded them of another time in New York's history when sirens blared weekly.

New York City's history with the air raid siren dates back to WWII. The city's first siren was installed on February 19, 1942 at Gerritsen Avenue and Avenue U, in Brooklyn. Mayor La Guardia purchased 435 sirens, due to fears of an air raid from Japan. He authorized $200,000 in total for enough sirens to cover the whole city. Starting on August 1st, 1942 every siren went off every Saturday at noon for a weekly test.

As the war raged on in Europe, air raid mania gripped New York. La Guardia and Police Commissioner Lewis J. Valentine bought ten "monster" air raid sirens built by Chrysler. The New York Times in July 1942 described them as "so powerful that they will carry for eight miles and will break the eardrums of any one standing within 200 feet." They hoisted one to the top of the RCA building in Rockefeller Center in six pieces. It weighed 5,300 pounds and had a 115 horsepower engine.

La Guardia's Civilian Defense team, with 418,000 members at its peak, listened for the sirens, knew the differences on signals and were ready to escort pedestrians to air raid shelters, if needed.

The sirens were important for the patriotic volunteers of the defense team, but regular New Yorkers soon grew dreary of the weekly drills and did what New Yorkers do best: they ignored them. An article in the New York Times about one of the first drills is titled, "City Nonchalant as Sirens Wail; Incidents Serious, Comic."

"Reactions throughout the city were as varied as the communities themselves. Times Square immediately adopted a 'so what?' attitude and went right on reading news bulletins. The Bronx, where Borough President Lyons loudly led the call for stronger sirens, was baffled. Brooklyn was just a bit tense. Queens was cool but alert. The lower East Side was both indifferent and confused; Harlem was nonchalant, and Little Italy was voluble about the whole business.

But in Times Square itself, crowds assembled to read the news bulletins were glassily indifferent to the siren that sounded the first alarm or to police orders to get off the streets.
No one in the midtown area seemed to rush for the subways. Shelter seems to be the last thing in the crowd's mind.

At Clinton and Grand Streets a character known as 'Yussel the Pretzel Peddler' got into an argument with an Irish patrolman. Yussel didn't want to go indoors because he had a basket of fresh pretzels to sell and Yussel won the argument."

Three years later, in 1945, when it became clear that the US would not be a target, the mayor disbanded the Civil Defense team, and tried to sell back all of its sirens. The city spent $75,000 to remove them and then put them on the market. The first bid was so low, they had to reject it, and the sirens were on sale a year later for as low as $95 each. Some were sold to fire houses in the outer boroughs and Long Island, but most were stripped for engine parts.

The blog Failed Messiah claimed that the sirens used today are leftover government property, as do several other blogs that have opposed the siren's wail. Because of how they were used in the past, the noise of the siren can be easily associated with an emergency or the drills from the 1940s. Older generations in particular find the noise to be disturbing; the website Jewniverse said the alarm was switched to orchestra music in some parts of Kensington and Midwood to appease neighbors.

The men outside of the Yeshivas that carry the sirens in Williamsburg assured me they are not government property, and shouldn't be associated with WWII.

"These weren't installed until 20 years ago," one man said. "I probably know the guy that made them. People come up with myths about us."

When I asked another man if their sirens were historical, he said, "These are not old. They run on a computer from the basement. It has nothing to do with the wars. Or the Pentagon."

So the sirens we hear aren't the same as their weekly WWII-era predecessors. But New Yorkers' characteristic indifference to the sound of the sirens appears to be the same as it was in the 1940s. As I waited on Bedford and Broadway, where the alarms blare loudly, pedestrians continued on their walks home without pause. I stopped into Motorino, on the corner, and asked if they could hear the alarms.

"Yeah, we hear them all the time," a bus boy said. "Whatever."