But the light poles are listening. In seconds, small sensors determine the location of the sound and send it to police headquarters. Microphones throughout the neighborhood begin eavesdropping. Cameras swivel and focus. Squad cars close in.
It's a staple scene from any science-fiction thriller: a city so wired that a citizen's every move is monitored. Now the technology looks to be on its way to Miami-Dade.
County Commissioner Joe Martinez set the surveillance ball rolling. This past May 26, he requested a report on procuring a "gunshot detection system" for the Miami-Dade Police Department. The commission will likely vote on whether or not to buy a system this summer.
If Martinez has his way, microphones and cameras will soon be perched atop buildings around town. Every time a gun goes off, the system will notify police of the location, number of shots, and even the caliber of bullet.Martinez, a former cop, says the idea has been floating around for a couple of years, but the price was simply too high. Then this spring, ShotSpotter -- one of two leading gunshot detection companies -- approached him. Instead of an up-front fee of several million dollars, the company could install a system for $50,000 per year for every one-mile radius covered. Martinez was intrigued.
"This is something that can save lives," he says, pointing out that similar systems have been installed in dozens of cities and counties across the nation in recent years.
Not everyone is convinced.
"It's not far-fetched that this equipment will also pick up conversations," fellow county Commissioner Barbara Jordan says. "On the one hand, I am very much positive about the fact that they are being proactive by tracking gunshots in neighborhoods, but I'm very concerned about our personal rights."
"This doesn't go into your home," Martinez counters. But he admits that outdoor conversations could be recorded. "I don't know what your expectation of privacy is if you're walking down the street or in a public park."
Accuracy is another issue.
"It could be a car backfiring" that triggers unwarranted surveillance, Jordan says. In fact, she's right: Systems around the country have been stymied by fireworks and other false alarms.
Even the cost is questionable. Martinez says the system would cover "the area where we have the highest concentration of gun violence," namely Overtown and Liberty City.
But that would run roughly $250,000 a year -- enough to put five cops on the street -- and would require coordination between Miami-Dade and Miami police.
Then again, with the number of police-involved shootings in the past year, maybe spying on Miamians is safer after all.