Active Noise Cancellation (ANC)

Active Noise Cancellation (ANC)

Active Noise Cancellation (ANC) is an advanced acoustic control technology based on the physical principle of "destructive interference", using electronic systems to actively generate anti-phase sound waves to cancel out specific in-cabin noise. In the era of intelligent vehicles, ANC technology captures cabin noise in real time via in-car microphones. Following high-speed processing by a Digital Signal Processor (DSP), it generates sound waves with identical amplitude but opposite phase to the original noise, which are then broadcast through the vehicle's audio system to neutralise sound pressure levels, significantly enhancing cabin quietness and NVH refinement. Once an exclusive feature in high-end luxury models, this technology is rapidly proliferating into mid-to-high-end new energy vehicles (NEVs), serving as a defining benchmark of the smart cockpit acoustic experience.

Core Technical Architecture and Working Principle

The technical architecture of an ANC system primarily comprises a noise acquisition module, a reference signal input module, a digital signal processing unit, and an in-car audio speaker output system.

On the noise acquisition front, multiple high-sensitivity noise-cancelling microphones are strategically positioned across the headlining, around the seats, or near the headrests to capture residual low-frequency cabin noise in real time. Concurrently, the system obtains engine speed signals, ignition pulses, or wheel vibration data via the CAN bus or dedicated sensors to accurately track the frequency characteristics of the noise source, providing vital reference inputs for precise anti-phase sound wave calculations.

The signal processing layer serves as the core computational hub of the ANC system. Upon receiving error signals from the microphones and reference signals, the DSP chip executes spectrum analysis and adaptive filtering calculations within milliseconds. Current mainstream algorithms include Filtered-x Normalized Least Mean Squares (FxNLMS) and Filtered-x Recursive Least Squares (FxRLS). By continuously tuning filter coefficients, the system dynamically tracks noise source frequency fluctuations to generate optimal anti-phase cancellation signals in real time. The processed signals are then amplified by a power amplifier and delivered through the in-car speakers, creating destructive spatial interference with incoming noise to achieve effective cabin noise reduction.

Key Application Scenarios and Technological Evolution

Automotive ANC technology primarily addresses two major noise scenarios. The first is Engine Order Cancellation (EOC), where the system captures engine speed signals to targetedly neutralise periodic, low-frequency booming noise at specific engine orders; traditional solutions such as BOSE can reduce low-frequency noise by 10 to 15 dB during engine idling. The second is Road Noise Cancellation (RNC). With NEVs lacking the masking effect of internal combustion engines, road and wind noise have become far more noticeable. To tackle broadband road noise generated by tyre-road friction, acceleration sensors mounted on the chassis or suspension capture vibration signals, which are analysed by dedicated algorithms to generate anti-phase sound waves. ZF's newly developed damping technology utilises chassis and integrated acceleration sensors to detect tyre roar in the ~200 Hz frequency range, deploying anti-phase signals via cubiX software through Continuous Damping Control (CDC) damper valves to achieve around 3 dB of road noise reduction, with potential gains of up to 10 dB in the future. In China, Huayan Huisheng's RNC system boasts an ultra-low latency of 3 ms and a peak noise reduction exceeding 10 dB, having already entered series production on models from SAIC IM, FAW Hongqi, and Ford, with fitments surpassing 50,000 units in 2024.

Industry Trends and Standards

ANC technology is transitioning from standalone hardware modules towards integrated cockpit domain control platforms. While traditional solutions relied on dedicated ANC hardware, the prevailing trend integrates ANC algorithms directly into the smart cockpit domain controller, utilising existing in-car sound systems to execute noise cancellation, which cuts hardware costs while bolstering system flexibility. CATARC Engineering Institute has developed a full-stack ANC solution spanning core algorithms to mass-production delivery; its proprietary ANC 3.0 version fully supports EOC and RNC, cutting development cycles by over 50% via the AI-powered ANC Flow toolchain. On the regulatory front, the national standard GB/T 46098—2025 "Performance Requirements and Test Methods for Automotive Active Noise Cancellation Systems"—drafted under the leadership of CATARC Engineering Institute—was issued in August 2025 and takes effect in March 2026, establishing a standardised evaluation framework for ANC performance and stability. Driven by carmakers' escalating demands for cabin quietness and the roll-out of new national standards, ANC is rapidly evolving from a premium option into standard equipment on mainstream models, establishing itself as a vital frontier in the smart cockpit acoustic experience.