Department of Ecology, Evolution, and Behavior, University of Minnesota-Twin Cities, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, USA.
J Acoust Soc Am. 2018 Oct;144(4):2354. doi: 10.1121/1.5064362.
Many animals communicate acoustically in large social aggregations. Among the best studied are frogs, in which males form large breeding choruses where they produce loud vocalizations to attract mates. Although chorus noise poses significant challenges to communication, it also possesses features, such as comodulation in amplitude fluctuations, that listeners may be evolutionarily adapted to exploit in order to achieve release from masking. This study investigated the extent to which the benefits of comodulation masking release (CMR) depend on overall noise level in Cope's gray treefrog (). Masked signal recognition thresholds were measured in response to vocalizations in the presence of chorus-shaped noise presented at two levels. The noises were either unmodulated or modulated with an envelope that was correlated (comodulated) or uncorrelated (deviant) across the frequency spectrum. Signal-to-noise ratios (SNRs) were lower at the higher noise level, and this effect was driven by relatively lower SNRs in modulated conditions, especially the comodulated condition. These results, which confirm that frogs benefit from CMR in a level-dependent manner, are discussed in relation to previous studies of CMR in humans and animals and in light of implications of the unique amphibian inner ear for considerations of within-channel versus across-channel mechanisms.
许多动物在大型社交群体中通过声学进行交流。其中研究得最好的是青蛙，雄性青蛙会形成大型繁殖群体，发出响亮的叫声来吸引配偶。尽管群体噪声对交流构成了重大挑战，但它也具有一些特征，例如幅度波动的共调制，这些特征可能是听众在进化上适应利用的，以实现从掩蔽中释放。本研究调查了共调制掩蔽释放 (CMR) 的益处在多大程度上取决于库普氏灰色树蛙（）中的整体噪声水平。在两种水平下，通过在群体噪声存在的情况下对发声进行测量，来测量被掩蔽信号的识别阈值。噪声要么未调制，要么调制的包络在频谱上是相关的（共调制）或不相关的（偏差）。在较高的噪声水平下，信噪比（SNR）较低，这种效应是由调制条件下相对较低的 SNR 驱动的，尤其是共调制条件。这些结果证实了青蛙以依赖于水平的方式受益于 CMR，这些结果与人类和动物中 CMR 的先前研究以及独特的两栖动物内耳对通道内与通道间机制的考虑的影响有关。
