"We're able to broadcast over a great distance. It's clearly underststood. there's no miscommunication. It's more effective than using a bullhorn," said Sergeant Chris Bielfeldt, Chicago Police.
The Chicago Police Department has purchased two LRAD units at $20,000 a piece. Their inaugural use may come NATO weekend as a means of delivering clear messages to crowds. There are 13 recorded messages which are meant to give fair warning to police directives, and an LRAD operator can also give live specific orders.
The LRAD can also emit high pitched alarm tones, which are not fun for the ear.
Police demonstrated the LRAD for ABC7 Monday afternoon at South Shore beach as we stood at water's edge, a football field from the speaker.
Pittsburgh police used the LRAD's alarm tones as a crowd attention getter when that city hosted the G20 in 2009. At least one lawsuit was filed by a resident claiming the LRAD damaged her hearing.
Chicago police say they will use the LRAD as a communications tool.
"We're using this as a messaging device," said Bielfeldt. "We're not using an alarm tone. We're using this to communicate messages. So alarm tones to those people who might think this is going to be used to bring people down by using alarm tones ... We're here to broadcast messages with the device."
The LRAD will be on stand-by Sunday when the largest permitted march arrives at Cermack and Michigan. The city is providing a stage and will permit roughly 45 minutes of speeches at that location before asking the crowd to disperse.
That 45 minutes will belong exclusively to Iraq and Afghanistan veterans like Aaron Hughes who intend to leave their NATO ribbons in protest of what they consider misguided wars.
"We want our voices to be the main message, and we want to be working with the police and everyone there because we think it's absolutely the human toll of this war which is on all sides," said Hughes.
The vets - perhaps three to four dozen - say they're intent upon a dignified ceremony, concluded by leaving their medals at a makeshift memorial at the intersection. After that, the crowd will be asked to disperse.