Experimental Studies of Communication

鸟类的发声交流系统长期以来一直是研究发声交流的模式系统。其中一个原因是鸟类的行为特别容易研究。另一个原因是鸟类的声音交流与人类的交流有很多相似之处，例如在发育和神经控制方面。在研究鸟类发声信号功能方面的进展最近得到了极大的帮助，因为使用了一种生物测定来测量雌性鸟类对雄性发声的偏好。在这项生物测试中，被圈养的雌性首先被激素雌二醇处理，然后被暴露在录音中的发声回放中。雌性对适当的发声做出回应，表现出求爱，这被用作回应措施。瑟西博士将通过给女性服用不同剂量的雌二醇，测量她们血液中的激素水平，并将剂量和血液水平与她们对声音刺激的反应程度联系起来，来研究生物检测的荷尔蒙基础。这些实验应该会促进我们对雌性鸟类生殖行为的荷尔蒙控制的理解，并导致对雌性发声偏好的生物测定的方法学改进。在第二个系列实验中，瑟西博士将测试发声的响度对女性偏好的影响。基于其他研究人员对青蛙的实验，已经提出了一些理论来解释为什么一些偏好可以通过改变音量来逆转，而另一些偏好则对这种变化不敏感。瑟西博士将测试这些理论是否可以推广到鸟类身上，作为统一生物声学领域的一步。在第三组实验中，瑟西博士将使用类似于人类辨别陌生声音的实验，测试雌性鸟类对不同雄性鸟类发出的声音进行分类的能力。这些实验将向产生适用于所有动物的声音交流理论又迈进一步，而不是只针对一个群体。

The vocal communication system of birds has long served as a model system for the study of vocal communication in general. One reason is that the behavior of birds is especially easy to study. Another reason is that avian vocal communication has so many similarities to human communication, for example, in development and in neural control. Progress in studying the function of avian vocal signals has recently been aided greatly by the use of a bioassay for measuring preferences of female birds for male vocalizations. In this bioassay, captive females are first treated with a hormone, estradiol, and then exposed to playback of recorded vocalizations. Females respond to appropriate vocalizations with a courtship display, which is used as the response measure. Dr. Searcy will investigate the hormonal basis of the bioassay by treating females with different doses of estradiol, measuring levels of the hormone in their blood, and relating dose and blood level to their degree of responsiveness to vocal stimuli. These experiments should both advance our understanding of the hormonal control of reproductive behavior in female birds and lead to methodological improvements in the bioassay for female vocal preferences. In a second series of experiments, Dr. Searcy will test the effect of loudness of vocalizations on female preferences. Based on other investigators' experiments with frogs, theories have been proposed to explain why some preferences can be reversed by changing loudness while others are insensitive to such changes. Dr. Searcy will test whether or not these theories can be extended to birds, as a step towards unifying the field of bioacoustics. In a third set of experiments, Dr. Searcy will test the ability of female birds to sort vocalizations produced by different males, using a technique similar to experiments on people's discrimination of unfamiliar voices. These experiments will provide another step towards producing theories of vocal communication that are general across all animals, rather than specific to just one group.