Vocalizations often contain both ‘dynamic’ information, related to short-term fluctuations in the individual's emotional states, and ‘static’ information, related to long-term attributes such as age, sex, weight and body size which define an ‘individual vocal signature’. While both types of information may be of functional value to receivers, dynamic information requires acoustic versatility, while static information depends on acoustic stability. Here we investigated whether an individual vocal signature is present across the vocal repertoire of the bonobo, Pan paniscus. First, the analysis of the acoustic structure of its five most common tonal vocalizations emphasized the highly graded structure of its repertoire. We then evaluated the reliability of identity information across these call types. The results show that, while all call types supported information related to identity, the reliability of these vocal signatures was not consistent along the graded vocal continuum. Caller identity was strongly encoded at one end of the acoustic gradation (high-hoot) and decreased from bark, soft bark, peep-yelp to peep calls. Strikingly, the reliability of the individual signature thus decreased from calls used in high-arousal contexts to those used in low-arousal contexts. To the best of our knowledge, this is the first demonstration that an acoustic gradation that codes for ‘dynamic’ information can be accompanied by variation in the ‘static’ information that supports vocal individuality.

中文翻译：

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个体声乐特征的可靠性因倭黑猩猩的分级曲目而异

发声通常包含与个人情绪状态的短期波动相关的“动态”信息和与诸如年龄、性别、体重和体型等长期属性相关的“静态”信息，这些信息定义了“个人的声音特征” '。虽然这两种类型的信息对接收者都可能具有功能价值，但动态信息需要声学多功能性，而静态信息则取决于声学稳定性。在这里，我们调查了倭黑猩猩 Pan paniscus 的声音曲目中是否存在个人声音特征。首先，对其五种最常见音调发声的声学结构的分析强调了其曲目的高度分级结构。然后，我们评估了这些呼叫类型中身份信息的可靠性。结果表明，虽然所有呼叫类型都支持与身份相关的信息，但这些声音特征的可靠性在分级的声音连续体中并不一致。来电者身份在声级（高声）的一端被强烈编码，并从吠叫、软吠、窥视呼喊到窥视呼叫减少。引人注目的是，个体签名的可靠性因此从高唤醒环境中使用的调用降低到低唤醒环境中使用的调用。据我们所知，这是第一次证明编码“动态”信息的声级可以伴随支持声音个性的“静态”信息的变化。来电者身份在声级（高声）的一端被强烈编码，并从吠叫、软吠、窥视呼喊到窥视呼叫减少。引人注目的是，个体签名的可靠性因此从高唤醒环境中使用的调用降低到低唤醒环境中使用的调用。据我们所知，这是第一次证明编码“动态”信息的声级可以伴随支持声音个性的“静态”信息的变化。来电者身份在声级（高声）的一端被强烈编码，并从吠叫、软吠、窥视呼喊到窥视呼叫减少。引人注目的是，个体签名的可靠性因此从高唤醒环境中使用的调用降低到低唤醒环境中使用的调用。据我们所知，这是第一次证明编码“动态”信息的声级可以伴随支持声音个性的“静态”信息的变化。