Kuala Besar, Kelantan: A sound speed analysis

Sound speed in seawater has been an interest to many researchers since the equations for sound speed was first published by Wilson in 1960. Generally, the speed of sound in water increases with the increasing temperature, salinity and pressure. However, other factors affecting sound speed are minor. Value of sound speed for fresh water and seawater at atmospheric pressure is approximately 1500 ms −1 . In this study, the sound speed of Kuala Besar, Kelantan was investigated. This shallow water area is an estuary area where the acoustic environment can change over in very short scales. The sound speed calculation was based on the field observation data of salinity, temperature and depth of Kuala Besar. Medwin formula was used in the calculation. The collected data showed a variation of sound speed between 1058.17–1100.46 ms −1 . The sound speed variations followed more the variations in salinity compared to variations in temperature for the stations at the transverse and longitudinal direction of the river. Therefore, in this study, the sound speed values were more influenced by salinity than temperature and followed the fact that salinity varies greatly in estuaries.