FIGURE 4.1. Average ambient noise spectrum for the deep sea. The diagonal line sloping downward from llOdB at 1Hz represents noise
due to geological activity from microseismic events to earthquakes. The diagonal line sloping upward at the highest frequencies reaching
40dB at 500kHz represents thermal noise. (From Urick 1983. Reprinted with permission
of The McGraw-Hill Companies)
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