Noise threatens human’s health both physically and psychologically. On the basis of insulation and absorption of sound, traditional passive method sustains poor performance in low frequency. By comparison, active noise control (ANC) technology shows excellent low-frequency properties and is widely investigated.
In the narrowband ANC system where the noise signal is a tonal one, it is very important to track the frequencies of the noise signal, especially when these frequencies change over time. However, conventional algorithms have some disadvantages in one way or another, such as biased results and high computational burden.
In order to track the noise tones, recently, a research team led by Prof. YANG Jun from the Institute of Acoustics (IOA) of Chinese Academy of Sciences proposed a new frequency estimation algorithm based on a parallel notch filter structure. The study was published in Signal Processing.
When combining the advantages of conventional algorithms and rejecting their weaknesses, the parallel notch filter structure presents high accuracy and low complexity.
The researchers first conducted the theoretical performance in detail in both the tracking accuracy of the frequency estimation and the noise reduction value of the active noise control system. The results of the performance analysis are very visual and accurate.
Then they provided simulations to verify the performance analysis of the frequency estimation. Experiments were conducted in an air pipe active noise control system (Figure 1).
Figure 1. Narrowband active noise control system (Image by WANG Han)
The simulations and experiment results revealed that the new algorithm has good performance. “Now, we can predict the noise reduction value accurately in a system with frequency mismatch or frequency estimation algorithm,” said YANG Jun.
Funding for this research came from the national natural science foundation of China (No.11474306) and Youth Innovation Promotion Association, Chinese Academy of Sciences.
This research team from the Institute of Acoustics (IOA) of the Chinese Academy of Sciences, which focuses on the active noise control, is led by Prof. YANG Jun and Prof. SUN Hongling. YANG Jun engages in the researches on sound, vibration and signal processing, especially in sound field control and array signal processing. They also make efforts in other system based on active noise control. They believe that active control will spread widely in the future.
WANG Han, SUN Hongling, SUN Yunping, WU Ming, YANG Jun. A Narrowband Active Noise Control System with a Frequency Estimation Algorithm Based on Parallel Adaptive Notch Filter. Signal Processing (Volume 154, Jan 2019, Pages 108-119), DOI:10.1016/j.sigpro.2018.08.012.
Institute of Acoustics, Chinese Academy of Sciences, 100190 Beijing, China