The primary acoustic property of seawater discussed here is the speed at which sound travels through it, which varies significantly depending on environmental factors.
Understanding Sound Speed in the Ocean
Sound travels much faster in water than in air. In the vast oceans, the speed of sound varies between 1,450 and 1,570 metres (about 4,760 to 5,150 feet) per second. This speed is not constant and is influenced by several factors.
Factors Affecting Sound Speed
The speed of sound in seawater is principally affected by three main factors: temperature, salinity, and pressure (depth). Based on the provided information:
- Temperature: As temperature increases, the speed of sound increases. Specifically, the speed of sound increases about 4.5 metres (about 15 feet) per second per each 1 °C increase in temperature. Warmer water allows sound waves to travel faster.
- Salinity: Higher salinity also leads to a higher speed of sound. The speed of sound increases about 1.3 metres (about 4 feet) per second per each 1 psu increase in salinity. Saltier water conducts sound more quickly.
- Pressure (Depth): While not detailed with specific rates in the provided reference, pressure (which increases with depth) is also a significant factor, generally causing the speed of sound to increase as depth increases.
These variations in sound speed are crucial for phenomena like sound channels (e.g., the SOFAR channel) and acoustic shadowing, which affect how sound propagates over long distances in the ocean. Understanding these properties is vital for sonar, underwater communication, and marine research.
