Characteristics of oceanic ambient noise measured at the Ieodo Ocean Research

Abstract

The Ieodo Ocean Research Station is an integrated meteorological andoceanographic observation base which was first constructed in Korea. It wasconstructed at the Ieodo underwater rock located at a distance of about 150 km tothe south-east of the Mara-do, the southernmost island in Korea. The structure isa fixed jacket type installed at a water depth of 40 m. In order to understand thecharacteristics of oceanic ambient noise at the station, the ambient noise wasmeasured during July 2004. A hydrophone was used to catch the noise at a depthof 20 m. The ambient noise levels at each frequency of one-third octave bandfrom 25 Hz to 12.5 kHz were analyzed and processed to get average and standarddeviation on noise levels. Dependences of wind speed and water current on thenoise levels were investigated. And shrimp sound was analyzed throughinvestigations of waveform and spectrum.