Sound Propagation

 

 

 

As we know, sound can move through media such as air, water, and even solids.  The properties of these media, such as density, motion, and viscosity, determine how well sound will propagate.

 

 

Sonar operates almost entirely on this principle.  The speed of sound can be calculated by using its mass density (rho) and bulk modulus (K) as shown below.

 

c_{\mathrm{fluid}} = \sqrt {\frac{K}{\rho}}

 

But since the effect of density is very small, the sound of speed underwater can also be determined by

 

4388 + (11.25 × T (°F)) + (0.0182 × depth (ft) + salinity (ppt))

 

From this equation, properties of sound traveling through water are made simple.  From the salinity, we can see that sound travels faster through the ocean than through fresh water.  Temperature and depth also play significant roles in the speed of sound underwater.

 

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