Bass — How Low Can You Go? Little Earthquakes!

Today’s cops are DJs weaving together a symphony of sirens, with motorists as muses:

There is the yelp, an electronic yodel that grabs attention at intersections or kicks off chases. There is the wail, more traditional; it sounds like the windup police sirens of yore. There is the “hi-lo,” dubbed the “European” siren by some, because it evokes the police chases seen — and heard — in French and Italian films.

The air-horn siren works well, officers say, for clearing intersections of pedestrians and getting the attention of speeding drivers. And the fast, or priority, siren sounds like an asteroid blaster from an old video game, and feels like a jackhammer assault on the ears.

That is the menu of sirens available to New York City police officers, each one making a specific impression, each at an officer’s fingertips. The sirens allow officers to choose sounds with a personal touch, like the conductors of a screeching, sound-bending orchestra.

And there is something new. Christened with a tantalizing name, the Rumbler, it sends out low, bone-rattling vibrations, so it is not only heard, but also felt. One has been tested on the streets of New York, but the jury is out on whether it is effective, offensive or terrifying.

. . .

Every time you hear that distinct and invasive wail, which may not technically be a wail, chances are the police officer behind it has made a deliberate, even aesthetic choice.

The decision is wholly subjective; there are no guidelines. Officers are simply told to mix the sirens up.

On a recent spin around Manhattan, up the Franklin D. Roosevelt Drive and then down the West Side Highway, Officer Spiros Komis, who has been with the highway patrol for 20 years, offered up an aural palette of what sirens he uses, and when. What would he do if he were chasing a speeding driver?

“I go through the whole mode,” he said, his fingers hovering above a dash-mounted keyboard that controls a police car’s lights and sounds.

“But I might start with a wail,” he said, pressing a button. The air filled with a familiar nasal drone. “And then I’d go to a constant yelp,” he said, and the car began bleating. A red Acura driving ahead promptly pulled right, into the center lane, its driver nervously checking his speed. “Then I’d give a little bit of the air horn; I’d give it a little toot,” he said, and gave it a little toot.

And then there’s the Rumbler:

To experience it is to feel a little earthquake beneath one’s feet.

Robert S. Martinez, director of the department’s fleet services unit, says the Rumbler has brought pedestrians and traffic to a dead stop every time he has tried out the test model. Departments in Alexandria, Va., and elsewhere in the Washington area already have Rumblers, according to Tom Morgan of Federal Signal, a leading siren supplier. It works like a bass-heavy boombox, sending out vibrations through two woofers.

But though the Rumbler is bound to grab the attention of even the most jaded New Yorker, it may frighten too many people, Mr. Martinez said.

“It’s debatable whether this would be good or bad for New York City,” he said. “You don’t want to hurt people’s ears. Even though it’s a lower decibel, it almost seems offensive.”