CONCLUSIONS 



PD of Ambient Ocean Noise 



The results obtained from the analysis of ambient 

 ocean-noise samples from the three locations indicate that 

 the hypothesis (that is, the assumption that the ocean 

 samples are taken from a gaussian noise distribution) is 

 not rejected when using "clean" ambient noise. The 

 hypothesis is rejected for "contaminated" ambient ocean 

 noise. The contamination may be ship noise, biological 

 noise, noise from ice (in polar regions), etc. Thus it has 

 been shown that ambient ocean noise, under certain con- 

 ditions, can be assumed to have a gaussian distribution 

 of amplitudes. 



PD of Ship Noise 



The same hypothesis used for the ambient noise 

 samples was used to test the ship samples. The results 

 indicate that ship-noise samples are not gaussian, since 

 six out of nine samples tested rejected the hypothesis that 

 the samples were taken from a gaussian distribution. It 

 was not found possible to distinguish between the types of 

 contamination of the ambient noise; that is, there were no 

 obvious differences in the probability density distributions 

 for ambient noise contaminated by ship noise and that con- 

 taminated by other sources. 



Comparison of Test Methods 



The method of moments was found to be the most 

 suitable, of the four methods of data reduction, for providing 

 the most accurate and useful estimates of the parameters. 

 However, when using this method the tails of the distribution 

 should not be left out of the calculations, since their con- 

 tribution at the higher moments is very significant. The 



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