Roberts Brian, Summers Robert J
Psychology, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, United Kingdom.
J Acoust Soc Am. 2015 May;137(5):2726-36. doi: 10.1121/1.4919344.
Recent research suggests that the ability of an extraneous formant to impair intelligibility depends on the variation of its frequency contour. This idea was explored using a method that ensures interference cannot occur through energetic masking. Three-formant (F1 + F2 + F3) analogues of natural sentences were synthesized using a monotonous periodic source. Target formants were presented monaurally, with the target ear assigned randomly on each trial. A competitor for F2 (F2C) was presented contralaterally; listeners must reject F2C to optimize recognition. In experiment 1, F2Cs with various frequency and amplitude contours were used. F2Cs with time-varying frequency contours were effective competitors; constant-frequency F2Cs had far less impact. To a lesser extent, amplitude contour also influenced competitor impact; this effect was additive. In experiment 2, F2Cs were created by inverting the F2 frequency contour about its geometric mean and varying its depth of variation over a range from constant to twice the original (0%-200%). The impact on intelligibility was least for constant F2Cs and increased up to ∼100% depth, but little thereafter. The effect of an extraneous formant depends primarily on its frequency contour; interference increases as the depth of variation is increased until the range exceeds that typical for F2 in natural speech.
近期研究表明，一个额外共振峰降低可懂度的能力取决于其频率轮廓的变化。使用一种确保干扰不会通过能量掩蔽发生的方法对这一观点进行了探究。使用单调的周期性声源合成了自然语句的三共振峰（F1 + F2 + F3）类似物。目标共振峰单耳呈现，每次试验中目标耳随机分配。F2的一个竞争者（F2C）对侧呈现；听众必须排除F2C以优化识别。在实验1中，使用了具有各种频率和幅度轮廓的F2C。具有随时间变化频率轮廓的F2C是有效的竞争者；恒定频率的F2C影响要小得多。在较小程度上，幅度轮廓也影响竞争者的影响；这种效应是累加的。在实验2中，通过将F2频率轮廓围绕其几何平均值反转并在从恒定到原始值两倍（0% - 200%）的范围内改变其变化深度来创建F2C。对可懂度的影响对于恒定的F2C最小，并且在深度增加到约100%之前增加，但此后变化不大。额外共振峰的影响主要取决于其频率轮廓；随着变化深度的增加干扰增加，直到该范围超过自然语音中F2的典型范围。
