The Canadian city of Winnipeg is trying some new sirens on for size – and these ones are having a big impact.

The Winnipeg Fire Paramedic Service outfitted several of their vehicles with a new siren system from Whelen Engineering that can send vibrations into cars via a low-frequency tone. The idea is that the sirens will be seen, heard, and now felt by other motorists who can allow emergency vehicles to pass more easily.

Tom Howards, the light fleet manager of the Winnipeg Fire Paramedic Service, says it will keep emergency teams safe as they drive through traffic on their way to a call.

Speaking with the Canadian media outlet CBC News, Howards said the device, a Whelen Howler, is “essentially a product somewhat like a big bass speaker.”

“The feedback from the operators is that it’s making a difference in their safety,” said Howards. How does it work? The frequency of the siren tone is slowed down by the Howler, thus creating vibrations that can be felt by other motorists.

The Winnipeg Fire Paramedic Service took the Howler for a spin in 2016 and liked it so much they decided to install the siren in all six of the chief of paramedic operations vehicles. The item looks like a black can of coffee grounds and is mounted behind the front bumper.

And while it is incredibly effective, the sound took some getting used for the people behind the Howler-fitted vehicles.

Michelle Bessas, a district chief of paramedic operations, also spoke with CBC News about her feelings towards the Howler. Bessas typically turns the siren on several times during her shift.

Bessas will turn on the Howler by pushing on the horn, and uses it most when entering an intersection, as this is the most common site of an accident for emergency vehicle drivers, where they may hit other cars not paying attention to the sirens.

“When the Howler goes off, we notice that everybody takes notice — they’re looking around and wondering what’s going on,” Bessas told a CBC reporter who accompanied her during a ride-along.

The Howlers are outfitted to the vehicles driven by the district chiefs, people like Bessas, who do not arrive at every call but rather the calls that are the most serious, calls that involve children, and calls that require advanced life support and bigger crews to handle the situation. They are not outfitted to every ambulance in the Winnipeg fleet, but one day they could be.

Not only are the vibrations difficult to ignore, but the Howler can also send signals and sounds twice the distance of a traditional siren. This, says Bessas, helps her get to scenes safely and quickly.

“A delay in our response in certain situations can really make a difference in the outcome of a patient — it can mean the difference between life and death or a permanent disability or making a full recovery,” said Bessas.

“We all want to go home safe at the end of the day, and we don’t want to cause anybody else to have a collision or to get injured.”

The Howlers were first used by ambulances in the Canadian city of Corner Brook, Newfoundland and are also being used by Calgary Police Service vehicles. Winnipeg is hoping to expand the use of Howlers but outfitting the rest of their rigs with the $1,500 apiece model, though the police force has only agreed to a test run of the device.