Dubno J R, Ahlstrom J B
Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston 29425, USA.
J Acoust Soc Am. 2001 Aug;110(2):1049-57. doi: 10.1121/1.1381023.
Forward- and simultaneous-masked thresholds were measured at 0.5 and 2.0 kHz in bandpass maskers as a function of masker bandwidth and in a broadband masker with the goal of estimating psychophysical suppression. Suppression was operationally defined in two ways: (1) as a change in forward-masked threshold as a function of masker bandwidth, and (2) as a change in effective masker level with increased masker bandwidth, taking into account the nonlinear growth of forward masking. Subjects were younger adults with normal hearing and older adults with cochlear hearing loss. Thresholds decreased as a function of masker bandwidth in forward masking, which was attributed to effects of suppression; thresholds remained constant or increased slightly with increasing masker bandwidth in simultaneous masking. For subjects with normal hearing, slightly larger estimates of suppression were obtained at 2.0 kHz rather than at 0.5 kHz. For hearing-impaired subjects, suppression was reduced in regions of hearing loss. The magnitude of suppression was strongly correlated with the absolute threshold at the signal frequency, but did not vary with thresholds at frequencies remote from the signal. The results suggest that measuring forward-masked thresholds in bandlimited and broadband maskers may be an efficient psychophysical method for estimating suppression.
在带通掩蔽器中，以0.5千赫和2.0千赫测量前掩蔽阈值和同时掩蔽阈值，作为掩蔽器带宽的函数，并在宽带掩蔽器中进行测量，目的是估计心理物理学抑制。抑制在操作上通过两种方式定义：（1）作为前掩蔽阈值随掩蔽器带宽的变化，以及（2）考虑到前掩蔽的非线性增长，作为有效掩蔽器电平随掩蔽器带宽增加的变化。受试者为听力正常的年轻成年人和患有耳蜗性听力损失的老年人。在前掩蔽中，阈值随掩蔽器带宽而降低，这归因于抑制作用；在同时掩蔽中，阈值随掩蔽器带宽增加而保持恒定或略有增加。对于听力正常的受试者，在2.0千赫而非0.5千赫处获得的抑制估计值略大。对于听力受损的受试者，在听力损失区域抑制作用减弱。抑制的程度与信号频率处的绝对阈值密切相关，但不随远离信号的频率处的阈值而变化。结果表明，在有限带宽和宽带掩蔽器中测量前掩蔽阈值可能是一种估计抑制作用的有效心理物理学方法。
