A new subband feedback cancellation scheme is proposed, capable of providing additional stable gain without introducing audible artifacts. The subband feedback cancellation scheme employs a cascade of two narrow-band filters Ai(Z) and Bi(Z) along with a fixed delay, instead of a single filter Wi(Z) and a delay to represent the feedback path in each subband. The first filter, Ai(Z), is called the training filter, and models the static portion of the feedback path in ith subband, including microphone, receiver, ear canal resonance, and other relatively static parameters. The training filter can be implemented as a FIR filter or as an IIR filter. The second filter, BI(Z), is called a tracking filter and is typically implemented as a FIR filter with fewer taps than the training filter. This second filter tracks the variations of the feedback path in the ith subband caused by jaw movement or objects close to the ears of the user.
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机译：提出了一种新的子带反馈消除方案，该方案能够提供额外的稳定增益而不会引入可听见的伪像。子带反馈消除方案采用级联的两个窄带滤波器A i （Z）和B i （Z）以及固定的延迟，而不是单个滤波器W i （Z）和一个延迟，代表每个子带中的反馈路径。第一个滤波器A i （Z）被称为训练滤波器，它对第i 子带中的反馈路径的静态部分进行建模，包括麦克风，接收器，耳朵根管共振和其他相对静态的参数。训练滤波器可以实现为FIR滤波器或IIR滤波器。第二个滤波器B I （Z）被称为跟踪滤波器，通常实现为FIR滤波器，其抽头少于训练滤波器。该第二个滤波器跟踪第i 子带中的反馈路径的变化，该变化是由下巴运动或靠近用户耳朵的物体引起的。
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