Penna Mario, Moreno-Gómez Felipe N
Programa de Fisiología y Biofísica, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Casilla 70005, Correo 7, Santiago, Chile,
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2014 Mar;200(3):171-81. doi: 10.1007/s00359-013-0875-x. Epub 2013 Dec 20.
The efficiency of acoustic communication depends on the power generated by the sound source, the attributes of the environment across which signals propagate, the environmental noise and the sensitivity of the intended receivers. Eupsophus emiliopugini, an anuran from the temperate austral forest communicates by means of an advertisement call of moderate intensity within the range for anurans. To estimate the range over which these frogs communicate effectively, we conducted measurements of call sound levels and of auditory thresholds to pure tones and to synthetic conspecific calls. The results show that E. emiliopugini produces advertisement calls of about 84 dB SPL at 0.25 m from the caller. The signals are affected by attenuation as they propagate, reaching average values of about 47 dB SPL at 8 m from the sound source. Midbrain multi-unit recordings show quite sensitive audiograms within the anuran range, with thresholds of about 44 dB SPL for synthetic imitations of conspecific calls, which would allow communication at distances beyond 8 m. This is an extended range as compared to E. calcaratus, a related syntopic species for which a previous study has shown to be restricted to active acoustic spaces shorter than 2 m. The comparison reveals divergent strategies for related taxa communicating amid the same environment.
声学通讯的效率取决于声源产生的功率、信号传播所经过的环境属性、环境噪声以及目标接收者的灵敏度。艾氏湍蛙（Eupsophus emiliopugini）是一种来自温带澳大利亚森林的无尾目动物，它通过发出中等强度的求偶叫声进行通讯，该强度在无尾目动物的叫声范围内。为了估计这些青蛙有效通讯的范围，我们对叫声的声级以及对纯音和合成同种叫声的听觉阈值进行了测量。结果表明，艾氏湍蛙在距离发声者0.25米处发出的求偶叫声声压级约为84分贝。信号在传播过程中会受到衰减影响，在距离声源8米处，声压级平均值约为47分贝。中脑多单位记录显示，在无尾目动物的听觉范围内，其听力图相当灵敏，对合成同种叫声的阈值约为44分贝，这使得在超过8米的距离也能进行通讯。与同域分布的相关物种卡氏湍蛙（E. calcaratus）相比，这是一个扩展的范围，之前的一项研究表明，卡氏湍蛙的有效声学空间长度限制在2米以内。这种比较揭示了相关分类群在同一环境中通讯时采用的不同策略。
