Gray L
Department of Otolaryngology-Head and Neck Surgery, University of Texas Medical School, Houston 77030.
Dev Psychobiol. 1993 Dec;26(8):447-57. doi: 10.1002/dev.420260803.
Masked thresholds were estimated at four frequencies (.25, .5, 1, and 2 kHz) in three levels of broadband noise (approximately 0, 10, and 20 dB/Hz) in over 100 chickens at 0 and 4 days of age. An adaptive procedure was based on delays in ongoing peeps that occurred when chicks heard the tones over the background noise. Masked thresholds decreased an average of 1 dB per day immediately after birth. This increasing sensitivity is more likely due to nonsensory factors, similar to distraction masking reported in human neonates, than to improving frequency resolution. Masked thresholds in these neonates are otherwise affected by spectrum level and frequency in the same way as the responses of mature subjects: thresholds increase by nearly 1 dB for each dB of increase in the spectrum level of the masker, and by approximately 3 dB for each octave of frequency. Thus, although elevated by some nonsensory effect, masked thresholds in newborn chicks are similar to those in humans.
在100多只0日龄和4日龄的雏鸡中，于三种宽带噪声水平（约0、10和20 dB/Hz）下，在四个频率（0.25、0.5、1和2 kHz）估计了掩蔽阈值。一种自适应程序基于雏鸡在背景噪声中听到音调时正在发出的啁啾声中的延迟。出生后，掩蔽阈值平均每天下降1 dB。这种敏感性的增加更可能是由于非感官因素，类似于人类新生儿中报道的分心掩蔽，而不是频率分辨率的提高。这些新生儿的掩蔽阈值在其他方面受频谱水平和频率的影响与成熟受试者的反应相同：掩蔽器频谱水平每增加1 dB，阈值增加近1 dB，频率每增加一个八度，阈值增加约3 dB。因此，尽管受到一些非感官效应的影响，新生雏鸡的掩蔽阈值与人类相似。
