Sound waves propagate more efficiently underwater than in the air due to the higher density of water. This higher density allows water molecules to come closer together, which promotes better transmission of sound vibrations.
Water is a medium much denser than air, with molecules being much closer together. As a result, when a sound wave travels through water, it vibrates these neighboring particles more easily, transmitting its acoustic energy more efficiently. This molecular proximity allows the sound wave to travel farther without quickly losing its intensity. In contrast, air is significantly less dense, so the molecules are more spaced out, which slows down the transmission of vibrations, making sound less effective for covering large distances. That's why we can hear a distant sound clearly underwater, while in air, it dissipates quickly.
Sound travels much faster in water than in air. Typically, underwater, sound travels at about 1500 meters per second, while in air, it peaks at around 340 meters per second. Why? It’s mainly because water is much more dense and rigid than air, so sound vibrations are transmitted quickly from one molecule to another. Imagine a row of tightly packed marbles: when the first marble hits the second, the shock travels very quickly to the last one. With spaced-out marbles, like in air, this transmission is slower. As a result, underwater, sounds move fast and far, allowing whales to communicate over kilometers and submarines to easily detect distant sounds.
Underwater, sounds travel longer distances without losing much energy, unlike in air where they dissipate quickly. Why? Simply because water is much denser and less compressible than air, which limits the loss of sound intensity due to friction or molecular disturbances. In short, acoustic vibrations tire much less quickly and remain audible far below the surface. It's a bit like shouting into a pipe rather than in a large empty room: the sound stays "trapped" and therefore travels further and more efficiently.
Underwater, temperature greatly affects the speed of sound: the warmer the water, the faster the molecules move, facilitating the rapid transmission of sound waves. For example, in tropical areas, sound travels significantly faster than at the poles. Salinity, that is to say, the amount of dissolved salt, also influences acoustic propagation. Saltier water is denser, which allows sound to travel more quickly and clearly. These two factors, temperature and salinity, sometimes create distinct layers underwater, forming true acoustic corridors through which sounds can travel over impressive distances.
When sound waves travel underwater, they often encounter changes between different layers of water or surfaces (such as the sea floor or the water's surface). Part of the sound waves is then abruptly stopped and reflected back: this is reflection. Another part changes direction as it enters a new layer: this is refraction. This phenomenon occurs due to variations in density or temperature in the water, somewhat like sound waves suddenly deciding to take a different, better path. These two phenomena alter the trajectory of sounds in the water, sometimes allowing them to travel very long distances while still remaining clearly audible. Under certain conditions, particularly when temperature layers vary significantly, these reflections and refractions even create a kind of acoustic channel where sound can easily travel, facilitating excellent propagation over long distances.
Did you know that the speed of sound underwater is about four times faster than in air (approximately 1500 m/s underwater compared to about 343 m/s in air at room temperature)?
Did you know that submarines use sonar (a technique based on the propagation of sound waves underwater) to detect objects, map the ocean floor, and locate other ships that are far away?
Did you know that the depth, temperature, and salinity of water directly influence the speed and range of underwater sounds, sometimes creating natural acoustic channels capable of transmitting sounds over very long distances?
Did you know that whales communicate over distances of up to several hundred kilometers underwater, thanks to the efficient propagation of sound waves in the marine environment?
Yes, temperature plays a crucial role. An increase in water temperature generally leads to an increase in the speed at which sound travels. Thus, thermal variations can create specific acoustic layers in the ocean, influencing the trajectory and effectiveness of sound waves.
Whales use very low sound frequencies (infrasound) that propagate efficiently underwater. Due to the low sound attenuation in the ocean and excellent acoustic conduction, these sounds can travel hundreds or even thousands of kilometers, allowing for long-distance communication.
Sound reflection occurs when sound waves encounter a surface such as the sea floor or the surface of the water and bounce back. Refraction refers to the change in direction of a sound wave when it passes through layers of water with different physical properties (such as temperature or salinity). These phenomena directly influence the range and clarity of sound in an aquatic environment.
Sounds perceived underwater are altered due to the increased efficiency of liquid acoustic conduction, which notably changes the timbre, the perceived intensity, and the speed at which we locate sound sources. Our human ear is primarily adapted to the aerial environment, so habituation to the aquatic medium results in a different auditory experience.
Underwater, the higher density allows molecules to be closer together, facilitating a faster and more efficient transmission of sound vibrations. Additionally, sound attenuation is lower, leading to a clearer propagation of sound over long distances.
0% of respondents passed this quiz completely!
Question 1/5
