Active Road-Noise Control and Active Noise Cancellation
Active noise cancellation (ANC) uses microphones, sensors, signal processing, and loudspeakers to create a controlled sound that reduces selected unwanted noise inside a vehicle. Active road-noise control (ARNC) is the automotive form aimed specifically at noise transmitted from the road, tires, and chassis.
Main forms
- General active noise cancellation: an umbrella term for systems that counter selected cabin noise with an electronically generated cancellation signal.
- Active road-noise control: detects road- and chassis-related input, often with accelerometers, and uses cabin microphones plus the vehicle audio system to reduce the resulting sound at occupied positions.
- Harmonic cancellation: targets repeating tones associated with rotating components such as an engine, driveline, or electric motor. It is related technology, but it is not the same task as broadband road-noise control.
What the system can and cannot do
ARNC can reduce parts of the low-frequency and broadband noise that become prominent as road surface, tire, and speed change. Bose describes a production approach using chassis sensors, microphones, an adaptive algorithm, and the vehicle sound system. Bose Automotive: active sound management and road-noise control
The technology does not make the cabin silent. Its result depends on sensor placement, loudspeaker coverage, processing delay, seat position, cabin calibration, tires, and road input. Short impacts, wind noise, and sound outside the system's useful range may remain. Passive measures such as seals, glazing, insulation, and structural design still matter.
For the audio signal chain, processing, and listening considerations, see Audio Systems in Electric Vehicles.