Nelson Paul C, Carney Laurel H
Department of Biomedical and Chemical Engineering, Institute for Sensory Research, Syracuse University, Syracuse, New York 13244, USA.
J Acoust Soc Am. 2006 Aug;120(2):978-90. doi: 10.1121/1.2213573.
The ability of psychoacoustic models to predict listeners' performance depends on two key stages: preprocessing and the generation of a decision variable. The goal of the current study was to determine the perceptually relevant decision variables in masked amplitude-modulation detection tasks in which the modulation depth of the masker was systematically varied. Potential cues were made unreliable by roving the overall modulation depth from trial to trial or were reduced in salience by equalizing the envelope energy of the standard and target after the signal was added. Listeners' performance was significantly degraded in both paradigms compared to the baseline (fixed-level modulation masker) condition, which was similar to those used in previous studies of masking in the envelope-frequency domain. Although this observation was broadly consistent with a simple long-term envelope power-spectrum model, there were several aspects of the data that were not. For example, the steep rate of change in threshold with masker depth and the fact that an optimal amount of envelope noise could enhance performance were not predicted by decision variables calculated directly from the stimulus envelope. A physiologically based processing model suggested a realistic nonlinear mechanism that could give rise to these second-order features of the data.
预处理和决策变量的生成。本研究的目的是确定在掩蔽调幅检测任务中与感知相关的决策变量，其中掩蔽器的调制深度是系统变化的。通过在试验之间改变整体调制深度使潜在线索变得不可靠，或者在添加信号后通过均衡标准信号和目标信号的包络能量来降低其显著性。与基线（固定电平调制掩蔽器）条件相比，在这两种范式中听众的表现均显著下降，基线条件与先前在包络频域掩蔽研究中使用的条件相似。尽管这一观察结果与简单的长期包络功率谱模型大致一致，但数据的几个方面并非如此。例如，阈值随掩蔽器深度的急剧变化率以及适量的包络噪声可以提高表现这一事实，并未被直接从刺激包络计算出的决策变量所预测。一个基于生理学的处理模型提出了一种现实的非线性机制，该机制可能导致数据的这些二阶特征。
