How do owls localize interaurally phase-ambiguous signals?
How do owls localize interaurally phase-ambiguous signals?
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猫头鹰如何定位耳间相位模糊的信号？
DOI：
10.1073/pnas.95.11.6465
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发表时间：
1998
影响因子：
11.1
通讯作者：
Konishi,M
中科院分区：
文献类型：
--
作者：
Saberi,K;Farahbod,H;Konishi,M
猫头鹰和其他动物，包括人类，利用耳朵之间声音到达时间的差异来确定声源在水平面上的方向。当一个间时差（interural time difference， ITD）以窄带信号（如音调）传递时，人们可能无法推导出该间时差所代表的方向。这是因为他们无法区分信号中包含的真正的过渡段和它的相位等效，即ITD±nT，其中是刺激音的周期，是一个整数。这种不确定性被称为相位模糊。当窄带信号中包含过渡段时，鸟类和哺乳动物中所有对过渡段敏感的神经元都会对过渡段及其相位等效物做出反应。然而，尚不清楚这些动物在窄带信号定位中是否表现出相位模糊。目前的研究表明，仓鸮（Tyto alba）在耳机传递的音调定位中经历了相位模糊。我们使用声音诱导的头部转向反应来测量两只猫头鹰感知到的声源方向。在这两种猫头鹰中，头部转动角度作为过渡段的正弦函数而变化。一只猫头鹰总是指向两个过渡段中较小的过渡段所代表的方向，而另一只猫头鹰总是选择较大的过渡段所代表的方向（即ITD - T）。
Owls and other animals, including humans, use the difference in arrival time of sounds between the ears to determine the direction of a sound source in the horizontal plane. When an interaural time difference (ITD) is conveyed by a narrowband signal such as a tone, human beings may fail to derive the direction represented by that ITD. This is because they cannot distinguish the true ITD contained in the signal from its phase equivalents that are ITD ±nT, whereTis the period of the stimulus tone andnis an integer. This uncertainty is called phase-ambiguity. All ITD-sensitive neurons in birds and mammals respond to an ITD and its phase equivalents when the ITD is contained in narrowband signals. It is not known, however, if these animals show phase-ambiguity in the localization of narrowband signals. The present work shows that barn owls (Tyto alba) experience phase-ambiguity in the localization of tones delivered by earphones. We used sound-induced head-turning responses to measure the sound-source directions perceived by two owls. In both owls, head-turning angles varied as a sinusoidal function of ITD. One owl always pointed to the direction represented by the smaller of the two ITDs, whereas a second owl always chose the direction represented by the larger ITD (i.e., ITD −T).