Pittsburgh City Council today began weighing the purchase of a system that can identify the site of a gunshot down to the street address -- at a cost of a few hundred thousand dollars per square mile.

ShotSpotter, a product of a Mountain View, Calif., company of the same name, has put its system in parts of 47 cities nationwide. A grid of 16 sensors in a given square mile pick up "snap, crackle and pop" sounds, differentiate gunfire and explosions from other noises, triangulate the sounds to pinpoint the location of the event, and within five or 10 seconds send data to law enforcement computers.

"This is a priority, because this is about stabilizing communities that are in trouble," said Council President Doug Shields, who is pushing for the prompt purchase of ShotSpotter. It could be deployed in city hot spots, he said. "That may involve the Hilltop communities, that may involve the Homewood-Brushton area, or Larimer."

Gregg Rowland, senior vice president of ShotSpotter, said the system allows police to respond quickly and appropriately to shots fired even if there was no 911 call. It then allows them to build a case, and its data is admissible in court.

At a special council meeting today, Mr. Rowland played a recording of a two-minute exchange of gunfire, which ShotSpotter was able to interpret.

"You've got a couple of different shooters and a vehicle is involved," he said during a break in the shooting. "A gun battle on the other side of that wall breaks out," he said, referring to a computer-generated map, "between two different shooters and two different guns.

"In less than two minutes, all of those rounds were fired . . . with, would you believe it? No 911 calls." Despite that, police and ambulances were able to arrive promptly, and prepared for multiple shooters and injuries. "No surprises."

Boston put in 120 sensors in a 6.2-square-mile area, Lt. Harry Cataldo of the Boston Police Department told council by phone. He downplayed any crime reduction effect, but said ShotSpotter helps police respond quickly and collect evidence.

"You have to look at it as a dispatch tool," he said. It gets appropriately equipped officers started on the way to a shooting scene "one to two minutes prior to the 911 call, which is a huge benefit."

The city's plan for an emerging system of anti-crime video cameras contemplates a ShotSpotter system, said Public Safety Director Michael Huss. He said the city already has a quote of $379,000 for a two-square-mile area gunshot detection network.

"That's not too bad of a price when you consider two square miles," said Mr. Huss. "I think it's a technology that could really help us."

Mr. Huss, though, said he didn't want to enter into a separate contract with ShotSpotter, but rather will work through the city's camera vendor, Maryland-based Avrio Group.

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