Lentz Jennifer J, Leek Marjorie R
Army Audiology and Speech Center, Walter Reed Army Medical Center, Washington, DC 20307, USA.
J Acoust Soc Am. 2003 Mar;113(3):1604-16. doi: 10.1121/1.1553461.
The ability to discriminate between sounds with different spectral shapes was evaluated for normal-hearing and hearing-impaired listeners. Listeners discriminated between a standard stimulus and a signal stimulus in which half of the standard components were decreased in level and half were increased in level. In one condition, the standard stimulus was the sum of six equal-amplitude tones (equal-SPL), and in another the standard stimulus was the sum of six tones at equal sensation levels re: audiometric thresholds for individual subjects (equal-SL). Spectral weights were estimated in conditions where the amplitudes of the individual tones were perturbed slightly on every presentation. Sensitivity was similar in all conditions for normal-hearing and hearing-impaired listeners. The presence of perturbation and equal-SL components increased thresholds for both groups, but only small differences in weighting strategy were measured between the groups depending on whether the equal-SPL or equal-SL condition was tested. The average data suggest that normal-hearing listeners may rely more on the central components of the spectrum whereas hearing-impaired listeners may have been more likely to use the edges. However, individual weighting functions were quite variable, especially for the HI listeners, perhaps reflecting difficulty in processing changes in spectral shape due to hearing loss. Differences in weighting strategy without changes in sensitivity suggest that factors other than spectral weights, such as internal noise or difficulty encoding a reference stimulus, also may dominate performance.
对听力正常和听力受损的受试者辨别具有不同频谱形状声音的能力进行了评估。受试者要辨别标准刺激和信号刺激，其中标准刺激的一半成分强度降低，另一半成分强度增加。在一种情况下，标准刺激是六个等幅纯音的总和（等声压级），在另一种情况下，标准刺激是六个等感觉级纯音的总和（相对于各受试者的听力阈值，等感觉级）。在每次呈现时，对各个纯音的幅度进行轻微扰动的条件下估计频谱权重。对于听力正常和听力受损的受试者，在所有条件下敏感性都相似。扰动和等感觉级成分的存在增加了两组的阈值，但根据测试的是等声压级条件还是等感觉级条件，两组之间在权重策略上仅测量到微小差异。平均数据表明，听力正常的受试者可能更多地依赖频谱的中心成分，而听力受损的受试者可能更倾向于使用边缘成分。然而，个体权重函数变化很大，尤其是对于听力受损的受试者，这可能反映了由于听力损失而在处理频谱形状变化方面存在困难。权重策略的差异而敏感性不变表明，除频谱权重之外的其他因素，如内部噪声或编码参考刺激的难度，也可能主导了表现。
