Within the next two years, the US and Europe will require all new electric and hybrid vehicles to make noise at low speeds so pedestrians hear them coming. But automakers and regulators are still not settled on what that noise should sound like. Nissan thinks the car should “sing.” Others think the sounds should be customizable. Now, Ayax — an independent Toyota manufacturer and distributor in Uruguay — has an even wilder idea: make the cars emit a sound that encourages plants to absorb nutrients and grow.

The idea was developed in cooperation with digital innovation firm The Electric Factory, a professional sound designer, and a “smart cities expert.” The group doesn’t go into too much detail on the website for the project, which is called Hy (an abbreviation of “harmony”), but a press release accompanying the announcement explains that they chose certain bandwidth and frequency ranges that are supposed to generate “improvements in growth, biomass, stomata (which favors water absorption and light use), and favoring cell division, fluids in cell walls, and protective enzymes.”

It’s a kooky idea, but it’s already rolling out in Uruguay

It’s a kooky idea, especially when viewed through the Hy Project’s promotional video, which could nearly be mistaken for parody. But as other automakers hesitate to share their low-speed noise plans, or in some cases even lobby for delays in the regulations, Ayax president Alejandro Curcio sees an opportunity for both his company and his country. As the first company in Latin America to assemble Toyota’s Hilux pickup truck in the 20th century, Curcio says the Japanese automaker (along with other companies) has continued to use Uruguay as a test bed for new ideas.

Curcio says Ayax is already retrofitting its car-sharing fleet of Prius C hybrids in Uruguay with electronics that let them emit the dynamic sound, and that Toyota has okayed spreading the pilot to similar fleets in Brazil and Argentina later this month. After that, he wants to present the idea to top Toyota executives in Japan. (The idea has been “very well received” by Toyota corporate in the early going, he says.)

Electric Factory co-founder Juan Ciapessoni is similarly optimistic about the group’s head start, and also the support it’s garnered from the Uruguayan government. “The whole idea of all of this is to go global,” he tells The Verge. “We took advantage of something that is going to be a must in the next few years worldwide.”

“We see ourselves within the Toyota ecosystem as upgraders, helpers, contributors, and this is a totally different angle that other brands were missing, and we’re happy to share it with Toyota,” he added.

While there is some evidence that acoustics have an effect on the growth of plants, the kind of big change that the Hy Project is aiming for sounds unfathomable; after all, the group calls the project the “world’s first sonic solution to heal the planet” in the press release. Reaching the scale required to back up that grandiose claim would require a lot more work than went into developing the sound in the first place — so will proving out any early results.

The Hy Project’s sound is more of a hum and thrum

Still, the sound the Hy Project group created is notably benign, almost soothing. For the most part, other automakers have so far tried to craft sounds that match the natural whine of electric motors without abandoning the way the audible feedback scales up in an internal combustion engine as the car goes faster — in other words, still loud and kind of brawny.

But the Hy Project sound is more of a low hum and thrum, with an oscillation that increases in frequency along with the car’s speed. I haven’t heard it in person, but in the sample videos it seems at the same time loud enough to alert pedestrians, but tranquil enough to placate others. It probably won’t please everyone, but then again, it seems no one in the industry has cracked what EVs and hybrids should sound like, so that’s to be expected.

For what it’s worth, Curcio says the early reactions to the noise in his own car have been kind. “I already put the Hy [technology] in my hybrid car and I feel fine, and everyone that gets into my car, they hear the sound and they go, ‘Wow. This is crazy!’,” he says. If other automakers continue to drag their feet on exactly how to meet the coming regulations, and Curcio’s headstrong rollout continues, perhaps more people outside Uruguay will get to experience the same thing.