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Study on the First Arrival Cycle Based Analysis Methods for Sound Speed of In Situ Acoustic Measurement in Water

The in-situ acoustic measurement is very important in geoacoustics and underwater acoustics. An in-situ acoustic instrument of Attenuation Array is used to measure sound speed of water to examine the different data analysis methods. Based on the first arrival cycle (FAC) judgment method, point judgment based data analysis method (PJDAM) and cross correlation based data analysis method (CCDAM) have the similar results of sound speed as 1479.4±0.6 and 1480.5±2.1 m/s respectively in a wide range of measurement frequency changing from 100kHz to 300kHz, which is very close to the standard sound speed of 1480 m/s of water measured in-situ with CTD. The analysis method will be useful in in-situ measurement of seafloor sediment.