The inaudible voice may be the next frontier in wildfire defense

A decade ago, two college students built a fire extinguisher Turn off the fire Using nothing more than a booming 10-inch subwoofer. The Internet has taken over, and Jimmy Fallon even booked a demo for it Tonight show.

But since that brief viral moment, there has been little more than a whisper about the technology.

Not for lack of trying. College students were not the first to prove this concept. DARPA was on the case In 2012; A search in the scientific literature reveals dozens of researchers studying the idea.

One startup now claims to have solved the problem. Sonic Fire Tech She built an audio fire suppression system that doesn’t just put out fires; It may also protect homes and other buildings from wildfires. The startup has raised a $3.5 million seed round from investors, including Khosla Ventures and Third Sphere, TechCrunch has learned exclusively.

Wildfires cost the United States as much $424 billion annually. It has become the problem Very sharp In places like California where insurance companies are located Refusal to renew policies After repeated fires turned large areas of the state into ashes.

Sonic Fire Tech has been developing its technology over the past several years. Michael Thomas, the startup’s CEO, was toying with the idea of ​​using sound to fight fires, and when he hit a wall, he reached out to Jeff Broder via LinkedIn. Broder worked at NASA, where he focused on heat and acoustics.

“This is kind of the founding story of a new era,” Browder, the startup’s CEO and CTO, told TechCrunch.

Broder was fascinated by Thomas’ idea and began building a prototype. “I got an amp and some parts from Home Depot and AutoZone and said, ‘Hey, let’s see if we can do anything better than what everyone else did,'” Broder recalls. “We put out a fire from seven feet away in my driveway.”

The startup quickly abandoned the subwoofer and moved to lower frequencies. The problem with audible frequencies, Browder said, is that any system powerful enough to suppress a fire would damage people’s hearing. “You basically have to throw the speaker design in the trash and start from scratch,” he said.

There are competing theories about how sonic energy could disrupt the combustion process, but the silent demonstrations certainly indicate that Sonic Fire Tech is onto something.

The new system uses a reciprocating piston very similar to the piston inside a car engine, but much larger. An electric motor drives the crankshaft, which pulses the two-foot-long piston to produce infrasound, the technical term for sound that is below the range of human hearing, or about 20 hertz.

“Because we designed everything ourselves, we lowered the frequency to where we are below the audible range, which helps us transmit more, and makes it safer,” Browder said.

Sonic Fire Tech’s current record is 25 feet. The larger system can operate up to 330 feet away, Browder said. The company plans to sell and install its system for about 2% of the home’s value, and is in talks with insurance companies to qualify this technology.

To protect the home, Sonic Fire Tech directs ultrasonic waves from a single generator through solid channels located at the edge of the roof and under the eaves. On the hills, they fire into the field to ignite any fires that might start in the debris in the gutters. Under the eaves, they are directed towards the ground to suppress any flames emerging near the walls. The system is triggered when sensors detect the presence of a flame.

The home system consumes about 500 watts of electricity, and in the event of a power outage, Sonic Fire Tech has plans to use lead-acid batteries for backup. Unlike sprinkler systems, it does not require a water source, which may be a shortage in wildfire country.

The startup is working with PG&E and Southern California Edison to demonstrate the technology in homes, and has signed a letter of intent with a chemical storage facility.

“The natural progression is that if we get certified as a sprinkler replacement, you can just run a pipe in your house and protect your kitchen and everywhere you need to protect it,” Browder said.