本稿では不快な騒音を音で制御・低減するアクティブノイズコントロール（ANC）について，これまでの技術の変遷を展望するとともに最近の動向について解説する．ANCはスピーカ（二次音源）からの制御音により騒音源（一次音源）からの騒音を制御・低減する技術であり，近年ではノイズキャンセリングヘッドホンなどを通じて一般にもその技術が広く知られるようになった．しかしながら，オフィスやイベント会場などの公共空間や車内や住宅内などの交通・住環境において，三次元的に騒音を制御することは未だ広くは実用化されていない．このような音空間において三次元的に騒音制御を実現するためには乗り越えるべき課題が多々残されている．本稿では，まずANCシステムを実装する上で重要となる消音領域（ZoQ）を任意の位置に移動させるバーチャルセンシングについて，代表的な3手法を紹介するとともに，それらの性能比較を示す．また，フィード...

We propose an active noise control (ANC) system for reducing periodic noise generated in a high field area such as noise generated from magnetic resonance imaging (MRI) devices (MR noise). The proposed ANC system utilizes optical microphones and piezoelectric loudspeakers, because specific acoustic equipment is required to overcome the high-field problem, and consists of a head-mounted structur...

Background and Aim: Exposure to impact noise (short-term, high intensity) higher than permitted levels results in injury to the auditory system. Armed forces are one of the occupational groups exposed to these types of noises resulting from gunshots. In this study, relevant articles and research on the adverse effects of impact noise, hearing loss, and tinnitus in armed forces and effective con...

Active noise control is gaining popularity in recent years. Especially, active control of impulsive noise is of great interest. Due to specific nature of such noise, standard approach to active control is not satisfying. This paper reviews existing algorithms specifically developed for impulsive noise control. Performance of the algorithms is verified using computer simulations and several nois...

An important step for active noise control (ANC) systems to be practical is to develop model independent ANC (MIANC) systems that tolerate parameter variations in sound fields. Reliabilities and stabilities of many MIANC systems depend on results of online system identifications. Parameter errors due to system identifications may threaten closed-loop stabilities of MIANC systems. A self-learnin...