Mikkel Christensen
A nearly silent car moving through a parking garage or crowded street might seem like a sign of modern engineering.
A nearly silent car moving through a parking garage or crowded street might seem like a sign of modern engineering.
But that quietness has forced regulators to rethink how vehicles signal their presence.
Hybrid and electric vehicles are now required to emit sound at low speeds under the Pedestrian Safety Enhancement Act of 2010.
According to the U.S. Department of Transportation, the rule was phased in in recent years to reduce risks linked to quieter vehicles.
In an article by BGR, the sound is described as most noticeable when a car is reversing or moving slowly, often heard as a steady hum.
The requirement reflects a broader shift in how electric-powered vehicles are experienced in everyday environments.
A new kind of warning
Electric propulsion has changed a long-standing assumption of road safety: that approaching vehicles can be heard.
At low speeds, these cars produce very little natural noise, making them harder to detect in places like parking lots and residential streets.
To address this, regulators mandated built-in sound systems that activate automatically, giving pedestrians an audible cue without driver action.
These tones are designed to be consistent and noticeable rather than loud or disruptive.
Safety by design
The reverse hum works alongside other safety technologies now common in modern vehicles.
The BGR report notes that features such as automatic emergency braking, blind-spot monitoring and lane departure warnings are widely used in hybrids and newer models.
Together, these systems replace what was once a passive safety cue, where engine noise alone helped signal a vehicle’s presence.
As quieter cars become more common, this combination of alerts and driver-assistance systems is playing a growing role in reducing low-speed accidents.
Sources: BGR
