GEOGRAPHICAL VARIATION OF AMBIENT NOISE 

 IN THE OCEAN FOR THE FREQUENCY RANGE 

 FROM 1 HERTZ TO 5 KILOHERTZ 



Robert L. Martin and Anthony J. Perrone 



New London Laboratory 

 Naval Underwater Systems Center 



Many statistical descriptions of ambient noise have been 

 published, among which are average spectrum level, 

 fluctuation versus frequency, average level versus depth, 

 cross correlation with wind speed versus frequency, 

 decorrelation time versus frequency, directionality, etc. 

 Each description provides information for various require- 

 ments such as system design, predictions, model evaluation 

 or to advance our knowledge of the causal phenomena 

 associated with the measurement. These statistical 

 descriptions vary widely with geographic area and it is 

 generally assumed that these variations result primarily 

 from differences in shipping densities, propagation con- 

 ditions and bottom topography. This paper describes 

 results obtained in many areas of the world and analyzed 

 using several of the statistical descriptors mentioned 

 above. The utility of the results to the various require- 

 ments is discussed and the need for measurements to form 

 the basis for broader interpretation of results from areas 

 of interest is highlighted. 



GEOGRAPHIC DEPENDENCE OF AMBIENT NOISE 



Observations of ambient noise level versus frequency have been 

 made in many areas of the world. These measurements provide valuable 

 descriptions of the areas when they are accompanied by information 

 on the parameters giving rise to the noise (e.g., wind speed, shipping, 

 etc.), the pecularities of the equipment used to make the measurement 

 (e.g. , analysis techniques, hydrophone depth) , time extent of the 

 measurement, and the hydrographic peculiarities of the area. In 

 addition to ambient noise level , there are other descriptors useful 



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