Conventional multiple-point active noise control (ANC) systems require placing error microphones within the region of interest (ROI), inconveniencing users. This paper designs a feasible monitoring microphone arrangement placed outside the ROI, providing a user with more freedom of movement. The soundfield within the ROI is interpolated from the microphone signals using a physics-informed neural network (PINN). PINN exploits the acoustic wave equation to assist soundfield interpolation under a limited number of monitoring microphones, and demonstrates better interpolation performance than the spherical harmonics method in simulations. An ANC system is designed to take advantage of the interpolated signal to reduce noise signal within the ROI. The PINN-assisted ANC system reduces noise more than that of the multiple-point ANC system in simulations.

The development of spherical sector harmonics benefits the sound- field decomposition and analysis over a spherical sector region. However, research on the soundfield radial extrapolation from one spherical sector region to another concentric sector region with a different radius is still insufficient. This paper presents a radial extrapolation method for spherical sector soundfields. Based on the extrapolation error and error sensitivity ratio, the performance and robustness of the proposed method is analyzed with different setups. Results show that the proposed method can achieve good performance, especially with a dual array sensor placement, a large angle range of the measurement region, and a small wave number.

This article proposes multiple circular arrays of vector sensors for analyzing the three dimensional sound field. By exploiting the fact that a finite number of spatial basis functions can represent the sound field within a region, the designed arrays allow the analysis of the sound field around the arrays sequentially by either a frequency-domain method or a time-domain method. The arrays are compact and thus are suitable for integrating with small-sized devices. The time-domain method is of low latency and computationally simple, and thus are suitable for providing the devices with spatial acoustic features in real-time. The effectiveness of the proposed arrays and the sound field analysis methods are confirmed by simulations, and compared with another array.

Active noise control system has been actively researched over the past half century, and implemented to reduce noises in ducts, headsets, and inside several automobile models. However, active control of noise fields, and specifically broadband noise fields, in rooms is still a barely explored topic due to the difficult of obtaining the reference signals, the challenge of online secondary path estimation, and the causal control constraint. In this paper, an active noise control system is developed that can cancel outgoing broadband noise fields in rooms. The proposed system decomposes the noise field on a sphere surrounding the noise sources into spherical harmonic modes, exploiting their directionality to generate the reference signals and remove the need for online secondary path estimation. A time-domain sound field separation algorithm and a time-wave domain adaptive algorithm allow the proposed system to meet the causal control constraint. Simulation results demonstrate that the proposed system can cancel broadband noise field globally in a room without suffering from the secondary source feedback problem.

One major issue of implementing broadband active noise control systems in reverberant rooms is the lack of reference signals. In this work, by exploiting the spatial sound field characteristics, a time-domain sound field separation method is developed to generate the reference signal for broadband active noise control systems in reverberant rooms. The time-domain sound field separation method separates the outgoing field produced by the primary source from the secondary source feedback and room reverberation on a spherical array, based on spherical harmonic decomposition of the sound field and the radial particle velocity measured by the array. Both the effectiveness of the time-domain sound field separation method and the applicability of the separated outgoing field as the reference signal for a broadband active noise control system in a reverberant room are demonstrated by simulations.