For a fixed sound source depth, the acoustical fields caused by high send frequency has strong sound intensity fluctuation, and their variation is sharp enough in an adjacent range.
对固定的声源深度，发射频率大的声场对应的声强起伏大，且相邻距离处起伏的强度很剧烈；
For exploring the direction of acoustical emission sources prior to earthquakes, assuming that the sound velocity is only dependent on depth, a formula of sound source direction can be derived.
为探索震前声发射的方向与地震的关系，假定声速仅与深度有关，在这种条件下得到的方向公式应该与恒速条件下得到的方向公式一致。
For exploring the direction of acoustical emission sources prior to earthquakes, assuming that the sound velocity is only dependent on depth, a formula of sound source direction can be derived.
为探索震前声发射的方向与地震的关系，假定声速仅与深度有关，在这种条件下得到的方向公式应该与恒速条件下得到的方向公式一致。
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