Randlett Lawrence’s frontyard sculpture, “Phantasma Gloria, ” rises above the street in a glittering cobalt blue wave, swaying in the breeze in the Echo Park neighborhood of Los Angeles.

在洛杉矶回声公园附近的街边，矗立起兰德利特·劳伦斯的前院雕塑作品：“幻影颂歌”。 它摇曳在微风中，钴蓝色的波纹闪闪发光。

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But an oak which has fewer but bigger leaves with stronger reflections, produces a jagged wave form, or what we called a rough echo.

但是，橡树的叶子少而又大，反射力较强，会产生参差不齐的声波，或所谓的“粗糙回声”。

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Echo Sounder is a kind of acoustic measuring depth equipment, which can measure depth with the time between transmitted wave and echo on condition in which the speed of ultrasonic is fixed.

回声测深仪是用来测量水深的一种声学测量设备，其以水中超声波的传播速度为确定条件，利用发射波与反射回波时间差来测量水深。

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