Active Noise Control Strategies and Systems

Active Noise Control (ANC) employs secondary sound sources to generate anti-noise that destructively interferes with unwanted sound, reducing overall acoustic energy in targeted zones. Core strategies include feedforward systems that predict incident noise using reference microphones; feedback systems that sense residual noise at error locations; and hybrid approaches combining both for improved stability and bandwidth. Advances in adaptive filtering—most notably the filtered-x least mean-square (FxLMS) algorithm and its variants—allow real-time adjustment of control filters to varying acoustic paths and signal characteristics. Virtual sensing techniques estimate acoustic pressure at inaccessible or moving locations, creating zones of quiet beyond physical sensor placement. Distributed sensor networks further extend control regions by sharing processing across multiple nodes. Practical applications span vehicle cabins, architectural openings, personal headrests and construction-site barriers, addressing both broadband and narrowband noise across the frequency spectrum. Ongoing challenges include managing algorithmic delays, ensuring causality, maintaining convergence under low signal-to-noise conditions and dynamic environments, and balancing computational complexity with real-time performance.

Research from Nature Portfolio

Recent studies have demonstrated the integration of head-tracking with local active control, using an array of external microphones and optical position sensors to maintain robust noise attenuation at ear positions up to 1 kHz despite listener movement. An active window system has been implemented on a full-sized domestic aperture, wherein optimally distributed loudspeaker modules and a single reference microphone achieve up to 10 dB global reduction of broadband environmental noise while preserving natural ventilation. In addition, a virtual ANC headphone concept has been explored using laser Doppler vibrometry to sense acoustic signals remotely via lightweight membranes in a head-and-torso simulator, realising over 10 dB attenuation across 500 Hz–6 kHz under complex sound fields and head motion.

Active Noise Control Strategies and Systems publication trend

The graph below shows the total number of articles in active noise control strategies and systems across all publications each year (not limited to Nature Index journals).

Technical terms

Feedforward control: A strategy that uses an upstream reference signal to anticipate and cancel incoming noise before it reaches the target zone.

Feedback control: A strategy that continuously measures residual noise at an error sensor and adjusts the anti-noise to minimise it.

Hybrid control: A combination of feedforward and feedback approaches to enhance bandwidth and stability.

Adaptive filter: A digital filter whose coefficients are updated in real time (e.g. via FxLMS) to track variations in the noise and acoustic path.

Virtual sensing: The estimation of acoustic pressure at uninstrumented or moving locations through models or auxiliary measurements.

Acoustic sensor network: A distributed arrangement of microphones and processors that collaboratively execute control algorithms.

References

1. A Review of Virtual Sensing Algorithms for Active Noise Control. Algorithms (2008).
2. Head tracking extends local active control of broadband sound to higher frequencies. Scientific Reports (2018).
3. Active control of broadband sound through the open aperture of a full-sized domestic window. Scientific Reports (2020).
4. A Hybrid Active Noise Control System for the Attenuation of Road Noise Inside a Vehicle Cabin. Sensors (2020).
5. Ultra-broadband local active noise control with remote acoustic sensing. Scientific Reports (2020).
6. Affine Projection Algorithm Over Acoustic Sensor Networks for Active Noise Control. IEEE Transactions on Audio Speech and Language Processing (2020).
7. Adjustable Structure for Feedback Active Headrest System Using the Virtual Microphone Method. Applied Sciences (2021).
8. Suitability of Active Noise Barriers for Construction Sites. Applied Sciences (2020).