In this paper we consider an in-ear headphone equipped with an external microphone and aim to minimize the sound pressure at the ear drum by means of a fixed feedforward ANC controller. Based on measured acoustic paths to predict the sound pressure generated by external sources and the headphone at the ear drum, the FIR filter coefficients of the ANC controller are optimized for different sound fields. Due to the acoustic feedback path between the loudspeaker and the microphone, a stability constraint based on the Nyquist stability criterion is introduced. Performance degradations due to reinsertions of the headphone and intra-subject variations are addressed by simultaneously optimizing the controller for several measurement repetitions of the acoustic paths. Simulations show that the controller optimized for an ipsilateral excitation produces an attenuation of at least -10 dB that extends approximately to +45{\deg} and -65{\deg} from the ipsilateral DoA. The controller optimized for a diffuse-field excitation achieves an attenuation of at least -10 dB over a wider range of DoAs on the ipsilateral side, namely +90{\deg} to -90{\deg}. Optimizing the controller for several measurement repetitions is shown to be effective against performance degradations due to reinsertions and intra-subject variations.
翻译:在本文中,我们考虑的是装有外部麦克风的内耳耳机,目的是通过固定的进料ANC控制器,最大限度地减少耳鼓的声压。根据测量的声学路径,以预测外部源和耳鼓耳机产生的声压,ANC控制器的FIR过滤系数为不同声域优化。由于扩音器和麦克风之间的声学反馈路径,根据Nyquist稳定性标准引入了稳定性限制。由于耳机和内部变异的重新安放而导致的性能退化,通过同时优化控制器,对声道的多次重复进行测量。模拟显示,优化的控制器优化后,将至少 - 10 dB 降至 +45 deg} 和 - 65 deg} 用于不同音响响音室的音效反馈路径。 用于扩散场振动的控制器优化使至少 - 10 dB 的性能退化, 相对于更大范围的DoA的重复性能, 即+90 和显示的自动变压至 内部变等。