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):1058-66. doi: 10.1121/1.1381024.
The objectives of this study were to measure suppression with bandlimited noise extended below and above the signal, at lower and higher signal frequencies, between younger and older subjects, and between subjects with normal hearing and cochlear hearing loss. Psychophysical suppression was assessed by measuring forward-masked thresholds at 0.8 and 2.0 kHz in bandlimited maskers as a function of masker bandwidth. Bandpass-masker bandwidth was increased by introducing noise components below and above the signal frequency while keeping the noise centered on the signal frequency, and also by adding noise below the signal only, and above the signal only. Subjects were younger and older adults with normal hearing and older adults with cochlear hearing loss. For all subjects, suppression was larger when noise was added below the signal than when noise was added above the signal, consistent with some physiological evidence of stronger suppression below a fiber's characteristic frequency than above. For subjects with normal hearing, suppression was greater at higher than at lower frequencies. For older subjects with hearing loss, suppression was reduced to a greater extent above the signal than below and where thresholds were elevated. Suppression for older subjects with normal hearing was poorer than would be predicted from their absolute thresholds, suggesting that age may have contributed to reduced suppression or that suppression was sensitive to changes in cochlear function that did not result in significant threshold elevation.
本研究的目的是测量在信号下方和上方扩展的带限噪声的抑制情况，包括在较低和较高信号频率下，以及在年轻和年长受试者之间，还有在听力正常和患有耳蜗性听力损失的受试者之间。通过测量带限掩蔽器中0.8千赫和2.0千赫处的前掩蔽阈值作为掩蔽器带宽的函数来评估心理物理学抑制。通过在信号频率下方和上方引入噪声成分同时保持噪声以信号频率为中心，以及仅在信号下方添加噪声和仅在信号上方添加噪声来增加带通掩蔽器的带宽。受试者包括听力正常的年轻和年长成年人以及患有耳蜗性听力损失的年长成年人。对于所有受试者，在信号下方添加噪声时的抑制比在信号上方添加噪声时更大，这与一些生理学证据一致，即纤维特征频率下方的抑制比上方更强。对于听力正常的受试者，高频时的抑制比低频时更大。对于患有听力损失的年长受试者，信号上方的抑制比下方降低得更多，且阈值升高。听力正常的年长受试者的抑制比根据其绝对阈值所预测的要差，这表明年龄可能导致抑制降低，或者抑制对耳蜗功能的变化敏感，而这种变化并未导致阈值显著升高。
