Shield Harvest With Sound

October 24, 2015 02:41 AM

Sonic net technology casts blanket over crops to keep out birds

Birds cost U.S. farmers more than $1 billion every year in crop losses and damage control. Grain, fruit, berries, aquaculture and other facets of agriculture take tremendous financial hits in an avian war of attrition from blackbirds, crows and European starlings. By casting a net of sound, researchers at the College of William & Mary might have found a means to shield farmers from a tremendous segment of bird damage.

John Swaddle, professor of biology, and Mark Hinders, professor of applied science, developed a system that projects sound through directional speakers aimed into a crop field. The sound occurs in the same frequency range birds use to communicate. Essentially, the sonic net serves as a blanket of sound, preventing birds from hearing each other, causing them to leave the area. 

Hinders is working with Midstream Technology to develop the sound system for commercial use. The intellectual property is the sound itself, which  uses a range of frequencies to cover multiple bird species. A combination of directional speakers shape the sounds and are positioned to contain noise within a given area. 

What does the sonic net sound like? “I liken the sound to a combination of natural gas escaping and alien cicadas,” says Sam McClintock, CEO, Midstream Technology. “We shape it so birds hear it and people don’t. The sound is benign, and the birds leave.” 

“If you stand inside the sound field, it sounds like a buzz,” Swaddle says. “Human and bird hearing overlaps a lot. However, if you stand outside the field, you can hardly hear much because the field contains the sound due to the speaker setup.”

Hinders and McClintock are working on speakers powered by solar panels and equipped with sensory microphones, only pumping out sound when birds are detected. In addition, they’re developing triggering mechanisms that respond only when particular bird species are present.  

In open field tests on starlings, sonic net technology has reduced overall bird presence by 80% for four consecutive weeks, Swaddle says. Pared down, the effect lasts, and the birds don’t habituate. “Birds get used to other prevention methods,” he notes. “The birds don’t get used to the sonic net because they can’t hear each other, and there’s no way to get around the risk of not hearing a predator.”

Sonic net is best suited for high-value crops, but Swaddle says any scale is possible, provided directional speaker access. For large farms, the sonic net patent application includes drone technology. The drones aren’t equipped with speakers but emit sound frequency based on drone material and propeller rotation. “The same sound from a speaker will come from the drone,” McClintock notes. “We want to develop a drone that performs its normal functions, yet produces the bird-deterring sound at the same time.”

Other sound technologies rely on an annoyance principal to fight bird presence, but sonic net technology stops communication. “It’s like humans in a pitch black room. We want out because we can’t see what’s happening,” Swaddle describes. “If a room next door has lights on, we’ll go there instead.” 

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