Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA.
Adv Exp Med Biol. 2013;787:239-46. doi: 10.1007/978-1-4614-1590-9_27.
Different models of the binaural system make different predictions for the just-detectable interaural time difference (ITD) for sine tones. To test these models, ITD thresholds were measured for human listeners focusing on high- and low-frequency regions. The measured thresholds exhibited a minimum between 700 and 1,000 Hz. As the frequency increased above 1,000 Hz, thresholds rose faster than exponentially. Although finite thresholds could be measured at 1,400 Hz, experiments did not converge at 1,450 Hz and higher. A centroid computation along the interaural delay axis, within the context of the Jeffress model, can successfully simulate the minimum and the high-frequency dependence. In the limit of medium-low frequencies (f), where f . ITD << 1, mathematical approximations predict low- frequency slopes for the centroid model and for a rate-code model. It was found that measured thresholds were approximately inversely proportional to the frequency (slope = –1) in agreement with a rate-code model. However, the centroid model is capable of a wide range of predictions (slopes from 0 to –2).
不同的两耳系统模型对正弦音的可听阈间差（ITD）做出不同的预测。为了检验这些模型，我们对关注高频和低频区域的人类听众的 ITD 阈值进行了测量。测量的阈值在 700 到 1000Hz 之间表现出最小值。随着频率高于 1000Hz，阈值的上升速度快于指数。尽管在 1400Hz 可以测量到有限的阈值，但在 1450Hz 及更高频率的实验并未收敛。在 Jeffress 模型的背景下，沿两耳延迟轴进行质心计算，可以成功模拟最小值和高频依赖性。在中低频（f）的极限下，其中 f. ITD << 1，质心模型和速率码模型的数学近似预测低频斜率。结果发现，测量的阈值与频率大致成反比（斜率 = –1），与速率码模型一致。然而，质心模型能够做出广泛的预测（斜率从 0 到 –2）。
