Derleth R P, Dau T
Carl-von-Ossietzky Universität Oldenburg, AG Medizinische Physik, Graduiertenkolleg Psychoakustik, Germany.
J Acoust Soc Am. 2000 Jul;108(1):285-96. doi: 10.1121/1.429464.
This study examines the role of temporal cues in spectral masking, such as beats and intrinsic envelope fluctuations. Predictions from the modulation-filterbank model developed by Dau et al. [J. Acoust. Soc. Am. 102, 2906-2919 (1997)] are compared to average masking patterns from Moore et al. [J. Acoust. Soc. Am. 104, 1023-1038 (1998)]. In these experiments, tones and narrow-band noises have been used as the signal and the masker, so that all four signal-masker combinations are considered. In addition, model predictions are compared with new experimental data in conditions of notched-noise masking, where the masker consisted of two narrow-band noises whose bandwidth and frequency separation were varied systematically. The model uses a peripheral filtering stage with linear and symmetric Gammatone filters, an adaptation stage that includes a static compressive nonlinearity for stationary input stumuli and a higher sensitivity for envelope fluctuation, and a modulation filterbank that analyzes the output for each peripheral channel. For low and medium masker levels, the model accounts very well for the masking patterns in all signal-masker conditions, as well as for the notched-noise conditions. In contrast, predictions from a version of the model that acts like an energy detector account for only some of the notched-noise data, and generally do not account for the shape of the masking patterns. For a high masker level, the simulations suggest the use of asymmetric filters, with a steeper high-frequency slope than is used in the linear model, consistent with results from previous studies. In addition, several nonlinear effects become apparent at this masker level, which cannot be accounted for by the current model.
本研究考察了时间线索在频谱掩蔽中的作用，例如拍音和固有包络波动。将Dau等人[《美国声学学会杂志》102, 2906 - 2919 (1997)]开发的调制滤波器组模型的预测结果与Moore等人[《美国声学学会杂志》104, 1023 - 1038 (1998)]的平均掩蔽模式进行了比较。在这些实验中，纯音和窄带噪声被用作信号和掩蔽音，从而考虑了所有四种信号 - 掩蔽音组合。此外，还将模型预测结果与带凹口噪声掩蔽条件下的新实验数据进行了比较，在该条件下，掩蔽音由两个窄带噪声组成，其带宽和频率间隔系统地变化。该模型使用一个具有线性和对称伽马通滤波器的外周滤波阶段、一个适应阶段（该阶段包括对平稳输入刺激的静态压缩非线性以及对包络波动的更高灵敏度）以及一个分析每个外周通道输出的调制滤波器组。对于低和中等掩蔽音水平，该模型很好地解释了所有信号 - 掩蔽音条件下以及带凹口噪声条件下的掩蔽模式。相比之下，一个类似能量探测器的模型版本的预测结果仅能解释部分带凹口噪声的数据，并且通常无法解释掩蔽模式的形状。对于高掩蔽音水平，模拟结果表明应使用不对称滤波器，其高频斜率比线性模型中使用的更陡峭,这与先前研究的结果一致。此外，在这个掩蔽音水平下，几个非线性效应变得明显，当前模型无法解释这些效应。
