雄性西藏蟾蜍的鸣声特征及听觉敏感性

Call Characteristics and Auditory Sensitivity of Male Bufo tibetanus

西藏蟾蜍(Bufo tibetanus)主要生活在海拔2 400～4 300 m的高海拔地区,本研究分析了这一高原两栖物种雄性个体的鸣声特征和听觉敏感性。采用录音机和指向性话筒,在野外记录西藏蟾蜍的广告鸣声,使用听觉脑干反应(ABR)检测听觉敏感性。采用Praat声音分析软件绘制广告鸣声的波形图和频谱图,鸣声特征参数通过Adobe Audition软件获取。广告鸣声由多个单音节鸣叫组成,鸣声主频为(1150±99)Hz。ABR对于刺激的响应以谷峰波形展示,听力图结果显示,听觉敏感区域在1.4～2.0 kHz,但在0.6～6.0 kHz范围的听觉阈值均高于70 dB,表明雄性西藏蟾蜍相较于其他物种听觉敏感性较差。尽管雄性西藏蟾蜍的最佳听觉敏感频率(1.6kHz)稍高于鸣声主频,但其鸣声能谱结构与听觉敏感性曲线在1.0～1.4 kHz存在一定程度重叠,符合"匹配过滤假说"。

The Tibetan Plateau Toad(Bufo tibetanus) lives in the plateau regions at 2 400-4 300 m above sea level. This is the first report to analyze the call characteristics and auditory sensitivity of male toad. Calls of 6 individuals were recorded by directional microphone connected to a digital audio recorder. Auditory sensitivity of 13 males was measured by auditory brainstem response(ABR). The waveform and spectrogram of advertisement calls were drawn using Praat software(Fig. 1). The acoustic properties were obtained using Adobe Audition software. The advertisement call of male toad consists of a single note with a dominant frequency of 1 150 ± 99 Hz. ABR to tone pips were characterized by valley-peak waveforms(Fig. 2). The audiogram shows that the most sensitive frequency region is 1.4-2.0 kHz, but the ABR thresholds are above 70 dB across 0.6-6.0 kHz which means that this toad has a poor auditory sensitivity compared with other species(Fig. 3). The power spectra of the male call overlap the audiogram at 1.0-1.4 kHz, which supported the matched filter hypothesis, although the best auditory sensitive frequency(1.6 kHz) is slightly higher than the dominant frequency of the male call.