During separation, infants of various species often produce a special call type, the separation cry, which elicits instant response from the caregiver. Ignoring this stimulus might be costly; hence, adults have evolved a sensitivity to infant cries. As the acoustic structure and function of these vocalizations are conserved across mammals, adults might react similarly to heterospecific and conspecific separation calls. The domestic dog, Canis familiaris, is an excellent model to study reactions to heterospecific vocalizations due to their special niche in the human social environment. Through domestication, they have become especially sensitive to human communicative signals, including baby cries. Furthermore, they can share their natural environment with other species such as other pets and livestock, which could also affect their responsiveness towards heterospecific calls. Taking advantage of this potential cross-species sensitivity, we aimed to examine dogs' reactions to infant separation calls of humans and domestic cats, Felis catus, compared to conspecific calls. To explore the effect of novelty and specific acoustic features we also used synthesized cries, which allowed us to look for general rules behind dogs' reactions to heterospecific calls and general acoustic effects functioning across species. After testing 100 dogs with pup cries in a previous study, here we tested another 118 dogs in three groups based on the presented sounds' origin. All stimuli were analysed acoustically; then we tested the effects of the species and acoustic features on the dogs’ behaviours. Dogs reacted to pup and artificial cries the fastest, and baby cries the slowest, while responses to kitten sounds were intermediate. We also found general acoustic effects: tonality-related parameters extensively affected the reactions. Higher noisiness caused faster speaker and owner orientation, but it seems that species-specific cues might overwrite the general acoustic rules that appear across mammal separation calls.

中文翻译：

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分离呼唤的跨物种效应：家犬对小狗、婴儿、小猫和人工声音的反应

在分离过程中，不同物种的婴儿通常会发出一种特殊的叫声，即分离哭声，这会引起看护者的即时反应。忽视这种刺激可能代价高昂；因此，成年人已经进化出对婴儿哭声的敏感性。由于这些发声的声学结构和功能在哺乳动物中是保守的，成年人可能会对异种和同种分离调用做出类似的反应。由于它们在人类社会环境中的特殊地位，家犬 Canisfamiliais 是研究对异种特定发声反应的极好模型。通过驯化，它们对包括婴儿哭声在内的人类交流信号变得特别敏感。此外，它们可以与其他物种（例如其他宠物和牲畜）共享自然环境，这也可能影响它们对异种特异性调用的响应。利用这种潜在的跨物种敏感性，我们旨在检查狗对人类和家猫 Felis catus 的婴儿分离呼叫的反应，与同种呼叫相比。为了探索新颖性和特定声学特征的影响，我们还使用了合成的叫声，这使我们能够寻找狗对异种特定叫声的反应背后的一般规则，以及跨物种起作用的一般声学效应。在之前的研究中测试了 100 只发出小狗叫声的狗之后，我们在这里根据所呈现声音的来源测试了三组中的另外 118 只狗。对所有刺激进行声学分析；然后我们测试了物种和声学特征对狗行为的影响。狗对小狗和人工哭声的反应最快，婴儿的哭声最慢，而对小猫声音的反应中等。我们还发现了一般的声学效应：与音调相关的参数广泛地影响了反应。更高的噪音会导致更快的说话者和主人定向，但似乎特定物种的线索可能会覆盖出现在哺乳动物分离呼叫中的一般声学规则。