Popov V V
Institute of Evolutionary Morphology and Ecology of Animals, Russian Academy of Sciences, Moscow.
J Acoust Soc Am. 1993 Jun;93(6):3490-5. doi: 10.1121/1.405679.
Sensitivity and interaural intensity difference (IID) dependence on sound frequency and direction was measured in an Amazon river dolphin Inia geoffrensis by recording the auditory nerve evoked response from the body surface. The maximal sensitivity in the horizontal plane was found when the sound direction was 5 degrees to 10 degrees ipsilateral to the recorded ear; the direction dependence of sensitivity was more pronounced at higher frequencies than at lower ones. The IID reached its peak at small azimuthal angles (7.5 degrees to 15 degrees) and higher sound frequencies (100 kHz), or at large azimuthal angles (30 degrees to 45 degrees) and lower sound frequencies (20 to 30 kHz). Each sound direction featured its specific pattern of spectral sensitivity and of interaural spectral difference. The interaural spectral difference fluctuated within a range of more than 20 dB depending on sound direction. The data indicate that interaural intensity as well as spectral difference may be cues for binaural localization of sound direction by dolphins.
通过记录来自体表的听神经诱发反应，测量了亚马逊河豚（Inia geoffrensis）的听觉灵敏度和双耳强度差（IID）对声音频率和方向的依赖性。当声音方向与记录耳同侧5度至10度时，在水平面内发现了最大灵敏度；在较高频率下，灵敏度的方向依赖性比较低频率时更为明显。IID在小方位角（7.5度至15度）和较高声音频率（100千赫）时，或在大方位角（30度至45度）和较低声音频率（20至30千赫）时达到峰值。每个声音方向都有其特定的频谱灵敏度和双耳频谱差异模式。双耳频谱差异根据声音方向在超过20分贝的范围内波动。数据表明，双耳强度以及频谱差异可能是海豚对声音方向进行双耳定位的线索。
