Sound is one of the components of our life, and a person hears it everywhere. In order to consider this phenomenon in more detail, we must first deal with the concept itself. To do this, refer to the encyclopedia, where it is written that “sound is elastic waves propagating in any elastic medium and creating mechanical vibrations in it”. In simpler terms, these are audible vibrations in an environment. From what it is, and the main characteristics of the sound depend. First of all, the speed of propagation, for example, the speed of sound in water differs from another medium.
Any sound analogue has certain properties (physical features) and qualities (a reflection of these signs in human sensations). For example, duration-duration, frequency-height, composition-timbre and so on.
The speed of sound in water is much higher than, for example, in air. Therefore, it spreads faster and is much further audible. This happens due to the high molecular density of the aqueous medium. It is 800 times denser than air and steel. It follows that the propagation of sound is largely dependent on the environment. Turn to specific numbers. So, the speed of sound in water equals 1430 m / s, in air - 331.5 m / s.
A low-frequency sound, for example, the noise made by a running marine engine, is always heard a little earlier than the ship appears in range. Its speed depends on several things. If the temperature of the water rises, then naturally the speed of sound in the water rises. The same thing happens with increasing salinity and pressure, which increases with increasing depth of the water. A special role on speed can be exerted by a phenomenon such as thermal wedges. These are places in which layers of water are found at different temperatures.
Also, in such places different density of water (due to the difference in temperature conditions). And when the waves of sound pass through such heterogeneous layers, they lose most of their strength. Faced with a thermal wedge, the sound wave is partially, and sometimes completely, reflected (the degree of reflection depends on the angle at which the sound falls), after which, on the other side of this place, a shadow zone is formed. If we consider an example when a sound source is located in a body of water above a thermocline, then hearing something altogether lower will be not only difficult but almost impossible.
Sound vibrations that are emitted above the surface are never heard in the water itself. And vice versa, it happens when the noise source is under the water layer: it does not sound above it. A vivid example of this is modern divers. Their hearing is greatly reduced due to the fact that water acts on the eardrum, and the high speed of sound in the water reduces the quality of determining the direction from which it moves. This blunts the stereo sound perception ability.
Under a layer of water, sound waves enter the human ear most of all through the bones of the skull of the head, and not like in the atmosphere, through the eardrum. The result of this process is its perception simultaneously with both ears. The human brain is not able at this time to distinguish between the places where the signals come from and in what intensity. The result is the emergence of consciousness that sound seems to roll from all sides at the same time, although this is far from the case.
In addition to the above, sound waves in a body of water have qualities such as absorption, divergence, and scattering. The first is when the power of sound in salt water gradually fades due to friction of the aquatic environment and the salts present in it. The divergence is manifested in the removal of sound from its source. It seems to dissolve in space like light, and as a result, its intensity drops significantly. And the oscillations disappear completely due to dispersion at all kinds of obstacles, heterogeneities of the medium.