Originally Posted by JD-EE
Indications seem to be the range should have been much greater than the 1700 meters that sticks in my memory.
I think I saw that figure in the Metron report. My estimate was 2-3km. I expect that Metron was intentionally conservative.
To answer your earlier question...
According to Urick, deep sea noise at 100Hz ranges from 60-80 db re 1uPa/sqrt-Hz, depending on sea-state and shipping activity. At 1kHz, the range is 45-70db, with decreased influence from shipping. At 10kHz it's down to 25-55db. At 100kHz: 25-35db, where the high side is still decreasing and the low side is rising due to thermal noise. The lowest of lows, not counting certain under-ice situations, is about 18db at 40kHz, sea-state 0, no shrimp or rain. The downward slope in those numbers is not constant, but has flatter and steeper areas, and is not even certain to be monotonically decreasing, due to the particular local sources of noise. Noise is understandably higher in shallow areas and enclosed bays by 5-15db over the max values above.