Centre for Audio, Acoustics and Vibration, University of Technology Sydney, Sydney, Australia.
Sci Rep. 2020 Nov 27;10(1):20784. doi: 10.1038/s41598-020-77614-w.
One enduring challenge for controlling high frequency sound in local active noise control (ANC) systems is to obtain the acoustic signal at the specific location to be controlled. In some applications such as in ANC headrest systems, it is not practical to install error microphones in a person's ears to provide the user a quiet or optimally acoustically controlled environment. Many virtual error sensing approaches have been proposed to estimate the acoustic signal remotely with the current state-of-the-art method using an array of four microphones and a head tracking system to yield sound reduction up to 1 kHz for a single sound source. In the work reported in this paper, a novel approach of incorporating remote acoustic sensing using a laser Doppler vibrometer into an ANC headrest system is investigated. In this "virtual ANC headphone" system, a lightweight retro-reflective membrane pick-up is mounted in each synthetic ear of a head and torso simulator to determine the sound in the ear in real-time with minimal invasiveness. The membrane design and the effects of its location on the system performance are explored, the noise spectra in the ears without and with ANC for a variety of relevant primary sound fields are reported, and the performance of the system during head movements is demonstrated. The test results show that at least 10 dB sound attenuation can be realised in the ears over an extended frequency range (from 500 Hz to 6 kHz) under a complex sound field and for several common types of synthesised environmental noise, even in the presence of head motion.
在局部有源噪声控制（ANC）系统中控制高频声音的一个持久挑战是在要控制的特定位置获得声学信号。在某些应用中，例如 ANC 头枕系统中，在人的耳朵中安装误差麦克风以提供安静或最佳声学控制环境是不切实际的。已经提出了许多虚拟误差感测方法，通过使用四个麦克风和头部跟踪系统的阵列来远程估计声学信号，以实现高达 1 kHz 的单个声源的降噪。在本文报道的工作中，研究了将激光多普勒测振仪的远程声学感测纳入 ANC 头枕系统的新方法。在这种“虚拟 ANC 耳机”系统中，在头和躯干模拟器的每个合成耳中安装了一个轻量级的背反射膜拾音器，以在最小侵入性的情况下实时确定耳朵中的声音。探索了膜的设计及其位置对系统性能的影响，报告了各种相关初级声场中耳朵中没有和有 ANC 的噪声谱，并演示了系统在头部运动期间的性能。测试结果表明，即使在头部运动的情况下，在复杂声场下和几种常见类型的合成环境噪声中，耳朵中的声音衰减至少可以在扩展的频率范围内（从 500 Hz 到 6 kHz）实现 10 dB。
