The city is poised to purchase a $1.5 million audio monitoring system that would allow the police department to track gunshots in sections of Boston most affected by violent crime. The city council was expected to approve a budget supplement at a meeting mid-day Wednesday to buy the system from a California-based company called SharpShooter Inc. Installation of the technology, which will include about 100 audio sensors stationed atop buildings over a six-square mile section of the city, will likely occur during the next two to three months.

City and police officials met with SharpShooter representatives at the police department's firing range on Moon Island in Quincy on Saturday morning for a system demo. As police officers fired shotguns and other weapons on the range, audio sensors stationed around the island picked up the gunfire, pinpointed the origin of the shots by triangulating information from several sensors, and transmitted data back to computer monitors inside an adjacent building. The shots showed up as red dots on a map of the range within feet of the spot where each weapon had been fired.

SharpShooter currently operates 16 systems in 13 cities across the United States, including Gary, Indiana, Minneapolis, Minnesota, and Washington D.C. Boston Police Commissioner Ed Davis said Saturday that Boston's version of the system is likely to cover parts of Dorchester, Mattapan, and Roxbury where a majority of the city's firearm crimes occur.

The epicenter of that zone will be the Bowdoin-Geneva neighborhood, which Davis has identified at several recent community meetings as the site of some of his most proactive attempts to curb shootings and violent crime.

When a shooting occurs, information is sent back to the emergency response center at police headquarters, where dispatchers can deploy officers to the scene. According to Gregg Rowland, senior vice president for ShotSpotter, the whole process takes just half a minute.

The sensors, which record sound continuously on a five-second loop and save that data when a noise registers as a shooting, can be used later to analyze more specific data, including the number of weapons, the caliber, and even the angle at which the shots occurred.

At community meetings stretching back over the last six months, residents in Meetinghouse Hill and Bowdoin Geneva have expressed their frustration not only with the frequency of gunfire in their neighborhoods, but also with what they say is a unnerving increase in the use of fire crackers. Particularly during the summer months, they say firecrackers are frustrating to residents who are eager to call 911 to report gunfire.

According to Rowland, the system has the sophistication to discern between gunfire and fireworks.

"The only sound that registers at over a mile is a gunshot," said Rowland.

He said that after a short adjustment period, the city's sensors will be calibrated to distinguish between a cacophony of urban disturbances such as gun shots, fireworks, or the backfire of an automobile.

"Every city sounds a little different," said Rowland.

If the system proves itself as a valuable tool, Davis said he may opt to supplant it with video cameras, a technique he used in high-crime sections of Lowell during his tenure as police commissioner there. He stressed that such a technique is not illegal in public places.

Asked if the audio and potential visual equipment infringed on the rights of Bostonians living under the system, Mayor Thomas Menino's response was firm.

"For people who illegally use guns, there are no privacy concerns whatsoever," he said. "I'm going to make the streets safe."

Davida Andelman, a Bowdoin-Geneva activist who works at the Bowdoin Street Health Center, agreed that thinking creatively about preventing crime should take precedent over personal privacy.

"In the absence of people making phone calls, I think it gives police a much clearer idea of where this activity is taking place and allows them to disperse police without waiting for community calls. It deals directly with people's own fear about calling and then facing retribution."

But some community leaders cautioned that the system would only be useful if integrated into a larger strategy to reconnect with community residents.

"It has to be part of an overall community policing strategy where your relationship with a community will inform what you're learning from the technology," said Michael Kozu, a community organizer at Project Right in Grove Hall.

The system was first proposed by City Councillor Rob Consalvo, who was approached by ShotSpotter representatives last year after he suggested the city use GPS technology to track shootings. On Saturday, Consalvo described the system, as a "mission-critical tool" and defended its cost, which includes a 15 percent annual maintenance fee on top of the initial purchase price.

City Council President Maureen Feeney, who will preside over the Wednesday meeting to approve the purchase, agreed that the purchase was a prudent expenditure. She said that the system seemed particularly suited for addressing a problem that impacts only a small percentage of the city; the system will cover just six square miles of Boston's nearly 90 mile spread.

"Unlike violence in a lot of other cities, the violence here is really centralized, so we'll get maximum use out of a focused system like this," said Feeney. "This takes responsibility off the shoulders of residents and puts it back on the shoulders of the police department."