Field Data Analysis 



Preliminary one-third octave band analysis of data on the five platforms 



in the Santa Barbara and Cook Inlet areas is described in a report entitled, 



"Field Measurements of Underwater Noise from Offshore Oil Operations from 

 January-June 1980" by David R. Schmidt, June 1980. 



Narrow band analysis has been performed on the recordings from Cook Inlet 

 and Atlantic City. These were obtained on the NOSC IDHACS (Intelligent Data 

 Handling and Control System) facility using the Spectral Dynamics SD 360 

 analyzer to provide analyses of the FM channel from 1 to 300 Hz with an 

 analysis bandwidth of 0.8 Hz, and the AM channel from 100 to 6000 Hz with an 

 analysis bandwidth of 16 Hz. Appendix A presents the hardcopy IDHACS printout 

 for one measurement location on semi-submersible platform Ocean Bounty. The 

 digitized data are for a station at a distance of approximately 50 feet from 

 the Ocean Bounty structure, and with hydrophone depth of 50 feet. The two 

 sets of data are identified by code numbers: 0B50A2BDA for the 15 Hz analysis 

 of the direct recording, and 0B05F2BDA for the 0.8 Hz analysis of the FM 

 recordings. 



Representative spectra for both the 16 and 0.8 Hz analyses are presented 

 in Figures 1 through 8 for platforms Ocean Bounty, King Salmon, Spark, and 

 Ocean Victory. Figures 1 and 2 are graphic presentations of the same data 

 from Ocean Bounty that is shown in digital form in Appendix A. The sharp 

 spikes indicate the presence of line spectra, with multiple single frequency 

 components in the above four platforms. Such line spectra are representative 

 of radiated noise from rotating machinery. Analysis is continuing in order to 

 relate the frequency components to individual machinery sources, and to 

 compare the magnitudes of noise on the various platforms. The magnitude data 

 will be available to estimate zones of potential acoustical influence about 

 the various platforms. 



Other Data Outputs 



Magnetic tape duplicates of portions of tape recordings of platforms Ocean 

 Bounty, King Salmon, and Spark have been furnished to the ARCO, Anchorage 

 office. 



A magnetic tape duplicate of portions of two drift runs of Ocean Bounty 

 has been provided to Polar Research, Inc. for use in connection with 

 BLM-sponsored studies of marine mammal response to acoustic playback of 

 platform radiated noise. 



E-5 



