Arehart K H, Rosengard P F
University of Colorado at Boulder 80309, USA.
J Acoust Soc Am. 1999 Apr;105(4):2454-65. doi: 10.1121/1.426850.
This study compared the ability of 5 listeners with normal hearing and 12 listeners with moderate to moderately severe sensorineural hearing loss to discriminate complementary two-component complex tones (TCCTs). The TCCTs consist of two pure tone components (f1 and f2) which differ in frequency by delta f (Hz) and in level by delta L (dB). In one of the complementary tones, the level of the component f1 is greater than the level of component f2 by the increment delta L; in the other tone, the level of component f2 exceeds that of component f1 by delta L. Five stimulus conditions were included in this study: fc = 1000 Hz, delta L = 3 dB; fc = 1000 Hz, delta L = 1 dB; fc = 2000 Hz, delta L = 3 dB; fc = 2000 Hz, delta L = 1 dB; and fc = 4000 Hz, delta L = 3 dB. In listeners with normal hearing, discrimination of complementary TCCTs (with a fixed delta L and a variable delta f) is described by an inverted U-shaped psychometric function in which discrimination improves as delta f increases, is (nearly) perfect for a range of delta f's, and then decreases again as delta f increases. In contrast, group psychometric functions for listeners with hearing loss are shifted to the right such that above chance performance occurs at larger values of delta f than in listeners with normal hearing. Group psychometric functions for listeners with hearing loss do not show a decrease in performance at the largest values of delta f included in this study. Decreased TCCT discrimination is evident when listeners with hearing loss are compared to listeners with normal hearing at both equal SPLs and at equal sensation levels. In both groups of listeners, TCCT discrimination is significantly worse at high center frequencies. Results from normal-hearing listeners are generally consistent with a temporal model of TCCT discrimination. Listeners with hearing loss may have deficits in using phase locking in the TCCT discrimination task and so may rely more on place cues in TCCT discrimination.
本研究比较了5名听力正常的受试者和12名中度至中度重度感音神经性听力损失的受试者辨别互补双成分复合音（TCCT）的能力。TCCT由两个纯音成分（f1和f2）组成，其频率相差Δf（赫兹），声级相差ΔL（分贝）。在其中一个互补音中，成分f1的声级比成分f2的声级高增量ΔL；在另一个音中，成分f2的声级比成分f1的声级高ΔL。本研究包括五种刺激条件：fc = 1000赫兹，ΔL = 3分贝；fc = 1000赫兹，ΔL = 1分贝；fc = 2000赫兹，ΔL = 3分贝；fc = 2000赫兹，ΔL = 1分贝；以及fc = 4000赫兹，ΔL = 3分贝。在听力正常的受试者中，互补TCCT的辨别（在固定的ΔL和可变的Δf情况下）由一个倒U形心理测量函数描述，其中辨别能力随着Δf的增加而提高，在一系列Δf值下（几乎）达到完美，然后随着Δf的增加再次下降。相比之下，听力损失受试者的群体心理测量函数向右移动，使得高于随机水平的表现出现在比听力正常受试者更大的Δf值处。在本研究中所包含的最大Δf值下，听力损失受试者的群体心理测量函数并未显示出表现下降。当在相等声压级和相等感觉水平下将听力损失受试者与听力正常受试者进行比较时，TCCT辨别能力下降是明显的。在两组受试者中，在高中心频率下TCCT辨别能力明显更差。听力正常受试者的结果通常与TCCT辨别的时间模型一致。听力损失受试者在TCCT辨别任务中可能在使用锁相方面存在缺陷，因此在TCCT辨别中可能更多地依赖于位置线索。
