O'Connell-Rodwell C E, Arnason B T, Hart L A
Center for Conservation Biology, Department of Biological Sciences, Stanford University, California 94305-5020, USA.
J Acoust Soc Am. 2000 Dec;108(6):3066-72. doi: 10.1121/1.1323460.
Seismic and acoustic data were recorded simultaneously from Asian elephants (Elephas maximus) during periods of vocalizations and locomotion. Acoustic and seismic signals from rumbles were highly correlated at near and far distances and were in phase near the elephant and were out of phase at an increased distance from the elephant. Data analyses indicated that elephant generated signals associated with rumbles and "foot stomps" propagated at different velocities in the two media, the acoustic signals traveling at 309 m/s and the seismic signals at 248-264 m/s. Both types of signals had predominant frequencies in the range of 20 Hz. Seismic signal amplitudes considerably above background noise were recorded at 40 m from the generating elephants for both the rumble and the stomp. Seismic propagation models suggest that seismic waveforms from vocalizations are potentially detectable by instruments at distances of up to 16 km, and up to 32 km for locomotion generated signals. Thus, if detectable by elephants, these seismic signals could be useful for long distance communication.
在亚洲象（Elephas maximus）发声和移动期间，同时记录了地震数据和声学数据。来自低频吼声的声学信号和地震信号在近距离和远距离时高度相关，在大象附近同相，而在离大象较远的距离处异相。数据分析表明，大象产生的与低频吼声和“跺脚”相关的信号在两种介质中以不同速度传播，声学信号传播速度为309米/秒，地震信号传播速度为248 - 264米/秒。两种信号的主频都在20赫兹范围内。对于低频吼声和跺脚，在距发声大象40米处记录到的地震信号振幅明显高于背景噪声。地震传播模型表明，发声产生的地震波形可能在距离仪器16公里处被检测到，而移动产生的信号在32公里处也可被检测到。因此，如果大象能够检测到这些地震信号，那么它们可能有助于长距离通讯。
