Silent Sound: The Next Frontier in Wildfire Defense

Imagine a fire extinguisher that uses sound instead of foam or water. A decade back, a pair of university students captured public attention by building exactly that, a device employing a powerful subwoofer to blast flames into submission. Their invention earned a viral spotlight and even a demonstration on a popular late-night television program. Yet, despite that initial excitement, the technology largely faded from view.

This disappearance wasn’t due to a lack of interest. Those students weren’t the pioneers; the Defense Advanced Research Projects Agency (DARPA) explored the concept as early as 2012, and scientific journals are filled with related research. Now, a new company asserts it has finally perfected the system. Sonic Fire Tech has developed an acoustic fire suppression system designed not only to douse fires but also to shield homes and structures from the threat of wildfires. The startup has successfully secured a $3.5 million seed investment from notable backers like Khosla Ventures and Third Sphere.

The urgency for such innovation is clear. Wildfires inflict an estimated $424 billion in costs on the United States every year. In states like California, the crisis has grown so severe that insurance providers are increasingly canceling policies in areas repeatedly scorched by massive blazes.

Over recent years, Sonic Fire Tech has been quietly advancing its technology. The company’s chairman, Michael Thomas, had long been experimenting with the idea of using acoustic energy against fire. When he encountered a technical hurdle, he connected on LinkedIn with Geoff Bruder, whose background includes work with NASA on heat and acoustics. Bruder, now serving as the startup’s CEO and CTO, describes the partnership as a modern founding tale.

Intrigued by the challenge, Bruder assembled a basic prototype using a subwoofer and components from local hardware stores. In a driveway test, they managed to extinguish a fire from a distance of seven feet. This early success prompted a major redesign. The team soon abandoned conventional speakers because producing sound loud enough to fight fires would be dangerously deafening. They realized they needed to start from the ground up.

The exact mechanism by which sound disrupts fire is still debated, but Sonic Fire Tech’s silent demonstrations provide compelling evidence that their approach works. Their current system operates like a massive car engine, using an electric motor to drive a crankshaft that moves a two-foot piston. This action generates infrasound, acoustic waves with frequencies below the range of human hearing, typically under 20 Hz.

Designing their own components allowed the team to drop into this safe, inaudible range, which also enables the sound to travel greater distances. Their present setup can suppress flames from 25 feet away, and Bruder believes a larger version could be effective from up to 330 feet. The company aims to price installation at roughly 2% of a home’s total value and is currently in discussions with insurance firms to have the technology officially certified.

For residential protection, the system uses a single generator to produce infrasound, which is then channeled through rigid ducts installed along the roof’s ridge and beneath the eaves. The ridge-mounted ducts direct sound downward to address fires potentially starting in gutter debris, while the eave ducts are aimed at the ground to quell flames near the walls. The entire network activates automatically the moment integrated sensors detect a fire.

A standard home unit consumes about 500 watts of power. To ensure operation during blackouts, the company is developing backup plans that incorporate lead-acid batteries. A significant advantage over traditional sprinklers is that the system requires no water, a critical benefit in drought-prone regions often plagued by wildfires.

Sonic Fire Tech is now collaborating with utility companies like PG&E and Southern California Edison to run demonstrations on actual homes. They have also signed a letter of intent with a chemical storage facility. Looking ahead, Bruder envisions a future where their acoustic system could be certified as a direct replacement for sprinklers, allowing pipes to be run inside a house to protect high-risk areas like the kitchen.

(Source: TechCrunch)