Experimental Studies of Communication

鸟类的声音交流系统长期以来一直是研究声音交流的模型系统。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。最近，利用生物测定法测量雌鸟对雄鸟发声的偏好，极大地促进了鸟类发声信号功能研究的进展。在这个生物测定中，圈养的雌性首先用激素雌二醇治疗，然后放录音的声音。雌性会对适当的叫声做出求爱的反应，这是一种反应方式。西西博士将研究生物测定的激素基础，用不同剂量的雌二醇治疗女性，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。这些实验既可以促进我们对雌性鸟类生殖行为的激素控制的理解，也可以促进雌性声音偏好生物测定方法的改进。在第二个系列的实验中，西西博士将测试声音的大小对女性偏好的影响。根据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声音来改变，而另一些则对这种变化不敏感。西西博士将测试这些理论是否可以扩展到鸟类，作为统一生物声学领域的一步。在第三组实验中，西西博士将测试雌鸟对不同雄鸟发出的声音进行分类的能力，使用的技术类似于人类对陌生声音的辨别实验。这些实验将为产生适用于所有动物的声音交流理论，而不是特定于某一群体，提供又一步。

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.