Freed Daniel J
Department of Human Communication Sciences and Devices, House Ear Institute, 2100 West Third Street, Los Angeles, California 90057, USA.
J Acoust Soc Am. 2008 Mar;123(3):1618-26. doi: 10.1121/1.2836767.
Adaptive linear filtering algorithms are commonly used to cancel feedback in hearing aids. The use of these algorithms is based on the assumption that the feedback path is linear, so nonlinearities in the feedback path may affect performance. This study investigated the effect on feedback canceller performance of clipping of the feedback signal arriving at the microphone, as well as the benefit of applying identical clipping to the cancellation signal so that the cancellation path modeled the nonlinearity of the feedback path. Feedback signal clipping limited the amount of added stable gain that the feedback canceller could provide, and caused misadjustment in response to high-level inputs, by biasing adaptive filter coefficients toward lower magnitudes. Cancellation signal clipping mitigated these negative effects, permitting higher amounts of added stable gain and less misadjustment in response to high-level inputs, but the benefit was reduced in the presence of the highest-level inputs.
自适应线性滤波算法通常用于消除助听器中的反馈。这些算法的使用基于反馈路径是线性的这一假设，因此反馈路径中的非线性可能会影响性能。本研究调查了到达麦克风的反馈信号削波对反馈消除器性能的影响，以及对消除信号应用相同削波的益处，以便消除路径模拟反馈路径的非线性。反馈信号削波限制了反馈消除器能够提供的额外稳定增益的量，并通过使自适应滤波器系数偏向较小幅度而导致对高电平输入的响应出现失调。消除信号削波减轻了这些负面影响，允许更高的额外稳定增益量，并且对高电平输入的响应失调更少，但在存在最高电平输入的情况下，益处会降低。
