There’s a new kind of police siren you don’t hear – as much as feel.  That’s because it emits low-frequency vibrations, literally making sound waves.  It’s called The Howler – it debuted in Florida – and is expanding quickly to other areas.

And even though people on the street find it unpleasant and irritating, officers think it's a safer and more effective means of announcing their presence. 

The Howler works by sending out a low-frequency vibration people can feel from up to 200 feet away. So why do vibrations work better than sound? Because there’s so much noise pollution in our lives – adding vibration to the lights and audible siren really gets people’s attention.  Hundreds of police departments around the country have started using the system, including the NYPD.

While officers think the Howler is a great improvement, not everyone is on board – particularly noise control groups. They call the Howler "disorienting." Because it easily triggers an involuntary stress response. That results in spikes in heart rates, muscle tension, and blood pressure. For example, NoiseOFF is a coalition aimed at reducing noise pollution. They say infrasound – as it’s called – is a sound energy that affects the nervous system and prolonged exposure can lead to progressive medical conditions.

But even though police officers and noise-control groups don’t not agree on the Howler, they do agree on one thing: You know when a police car is coming.