Studying pup isolation calls of wild rodents provides background for developing new early-life animal models for biomedical research and drug testing. This study discovered a highly complex acoustic phenotype of pup isolation calls in 4–5-days-old Mongolian hamsters Allocricetulus curtatus. We analysed the acoustic structure of 5010 isolation calls emitted in the broad range of frequencies (sonic, below 20 kHz, and ultrasonic, from 20 to 128 kHz) by 23 pups during 2-min isolation test trials, one trial per pup. In addition, we measured five body size parameters and the body weight of each pup. The calls could contain up to three independent fundamental frequencies in their spectra, the low (f0), the medium (g0) and the high (h0), or purely consisted of chaos in which the fundamental frequency could not be tracked. By presence/absence of the three fundamental frequencies or their combinations and chaos, we classified calls into six distinctive categories (Low-Frequency-f0, Low-Frequency-chaos, High-Frequency-g0, High-Frequency-h0, High-Frequency-g0+h0, High-Frequency-chaos) and estimated the relative abundance of calls in each category. Between categories, we compared acoustic parameters and estimated their relationship with pup body size index. We discuss the results of this study with data on the acoustics of pup isolation calls reported for other species of rodents. We conclude that such high complexity of Mongolian hamster pup isolation calls is unusual for rodents. Decreased acoustic complexity serves as good indicator of autism spectrum disorders in knockout mouse models, which makes knockout hamster models prospective new wild animal model of neurodevelopmental disorders.

中文翻译：

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蒙古仓鼠幼崽隔离叫声的声学复杂性：三频现象和混沌

研究野生啮齿动物的幼崽隔离叫声为开发用于生物医学研究和药物测试的新的早期动物模型提供了背景。这项研究发现了 4-5 天大的蒙古仓鼠 Allocricetulus curtatus 幼崽隔离叫声的高度复杂的声学表型。我们分析了 23 只幼犬在 2 分钟的隔离测试试验中以各种频率（低于 20 kHz 的声波和 20 至 128 kHz 的超声波）发出的 5010 次隔离叫声的声学结构，每只幼犬一次试验。此外，我们还测量了每只小狗的五个身体尺寸参数和体重。这些呼叫的频谱中最多可以包含三个独立的基频：低（f0）、中（g0）和高（h0），或者纯粹由无法跟踪基频的混沌组成。通过存在/不存在三个基频或其组合和混乱，我们将呼叫分为六个不同的类别（低频-f0、低频-混沌、高频-g0、高频-h0、高频-h0） -g0+h0，高频混沌）并估计每个类别中呼叫的相对丰度。在类别之间，我们比较了声学参数并估计了它们与幼犬体型指数的关系。我们通过其他啮齿类动物幼崽隔离叫声的声学数据来讨论这项研究的结果。我们得出的结论是，蒙古仓鼠幼崽的隔离叫声如此复杂，对于啮齿类动物来说是不寻常的。在基因敲除小鼠模型中，声学复杂性的降低是自闭症谱系障碍的良好指标，