Lotus, the British performance carmaker, has introduced a new device that makes hybrid cars louder. Since hybrid cars first hit the market, concerns have been raised about the potential risk to blind pedestrians—as well as children and cyclists—who may not hear hybrids, which can be very quiet. Citizen organizations, such as the National Federation of the Blind, have pushed for legislation to address the issue.

Lotus engineers believe they have a solution. The new system, dubbed “Safe and Sound,” was designed to generate artificial noise mimicking a gas-powered combustion engine. It utilizes an external waterproof speaker positioned next to the car’s radiator which emits fake engine noise during electric-only operation. The sound also changes frequencies based on the car’s speed to simulate common engines. And because the speaker faces to the front, the noise is virtually inaudible to occupants of the vehicle. Lotus used the Toyota Prius to demonstrate the device.

“Our advanced external sound synthesis technology increases pedestrian safety, while retaining the car’s environmental benefits,” said Mike Kimberly, chief executive officer of Group Lotus, in a company press release. “We hope that legislators introduce minimum noise requirements for vehicles to encourage the adoption of technologies such as ours.” There is no indication when Lotus might bring its technology to market, or how much it would cost.

Earlier this year, Lotus created a new research group solely for developing electric and hybrid technology—but has not announced production plans for its own hybrid vehicle.