How does the sound in the air differ from the sound in the water?

Sound waves can travel through solids, liquids and gases. In fact, they don't exist at all unless there is something they can travel for. The way sound travels through water differs from how it travels through air, but what are these differences?


The sound is measured in amplitude. A loud noise is described as being of great amplitude, while a quieter or softer one has a low amplitude. The word & # 39; amplitude & # 39; it actually refers to the pressure change caused by a passing sound wave: louder sounds create more pressure and carry more energy than those of smaller amplitude.

Energy and power

& # 39; Intensity & # 39; It is the name given to the amount of power transmitted by a sound wave through a specific area, and is measured in watts per square meter. The higher the number of watts, the more & # 39; intense & # 39; The sound wave

Decibels and relative sound levels

Scientists like to work at relative sound levels, using proportions. For this, the sound is measured in decibels (dB), instead of watts per square meter. The reference intensities are different for sound levels in the water and sound levels in the air.

In water, scientists use a reference intensity of 1 micropascal (μPa) pressure, while in air the reference intensity is 20 micropascals, which is the minimum intensity that young adults can comfortably hear.

How sound waves travel through air and water

You cannot measure the intensity of a wave without also taking into account the material or the medium through which it travels. The density of that material has an impact, since the air is significantly less dense than water. Similarly, the speed at which a sound travels, where it travels much faster through water than through air, must be considered.

The denser the medium is, and the faster the sound waves are, the lower its intensity. Since sound travels faster through water than air, and since water is also denser, sound has a lower intensity in water than in air.

How relative intensities play their role

Sound waves with the same intensities in air and water, when you measure in watts per square meter, actually have different relative intensities when you measure in decibels. The difference is 61.5 dB, composed of 35.5 dB due to different speeds and sound densities, and 26 dB due to different reference pressures. This should be subtracted from the levels measured in the water to compare them directly with the levels in the air, giving absolute intensity.

Report sound levels

When you are reporting sound levels, you should not use decibels as your unit of measurement. You also need to add the reference level. In the water, it will measure the intensity in & # 39; dB re 1 μPa & # 39;, and in the sound & # 39; dB will measure in & # 39; dB re 20 μPa & # 39;.