Nelson D A, Pavlov R
University of Minnesota.
J Speech Hear Res. 1989 Jun;32(2):298-306. doi: 10.1044/jshr.3202.298.
Previous research has shown that frequency-specific estimates of auditory time constants for recovery from short-term adaptation can be made using a fixed-probe forward-masking procedure (Nelson & Freyman, 1987) if the masker and the probe stimuli are at the same frequency. This study examines the validity of time-constant estimates for off-frequency forward-masking conditions in which the masker frequency is below (900 Hz) or above (1100 Hz) the probe frequency (1000 Hz). Fixed-probe-level temporal masking functions were obtained from four normal-hearing and four hearing-impaired listeners. Auditory time constants were estimated with iterative least-squares procedures to derive parameter values for an exponential model of recovery from forward masking. After appropriate corrections were made for attenuation to the maskers provided by the auditory filter centered at the probe frequency, recovery from forward masking produced by either off-frequency or on-frequency maskers could be described by a single time constant. That time constant was around 50 ms in normal-hearing listeners and was larger in those hearing-impaired listeners who demonstrated moderate hearing loss at the probe frequency.
先前的研究表明，如果掩蔽声和探测刺激处于相同频率，那么使用固定探测前向掩蔽程序（Nelson & Freyman，1987）就可以对从短期适应中恢复的听觉时间常数进行频率特异性估计。本研究考察了在掩蔽声频率低于（900赫兹）或高于（1100赫兹）探测频率（1000赫兹）的异频前向掩蔽条件下时间常数估计的有效性。从四名听力正常和四名听力受损的受试者中获得了固定探测水平的时间掩蔽函数。使用迭代最小二乘法程序估计听觉时间常数，以得出前向掩蔽恢复指数模型的参数值。在对以探测频率为中心的听觉滤波器对掩蔽声的衰减进行适当校正后，异频或同频掩蔽声产生的前向掩蔽恢复情况都可以用一个时间常数来描述。该时间常数在听力正常的受试者中约为50毫秒，在那些在探测频率处表现出中度听力损失的听力受损受试者中则更大。
