Definition of Ultrasound and Infrasound

Acoustics is a discipline of physics that studies the principles and phenomena related to sound. When the sound waves have a frequency that exceeds 20,000 Hz, it is called ultrasound. If the frequency is lower than what the human ear can perceive, it is called infrasound.

Applications of ultrasound and scientific curiosities

Ultrasound technology has a wide range of applications: in the aesthetic and medical sectors restorative, in ultrasound or lithotripsy devices, in industrial applications or in some areas of the chemistry.

In the field of medicine, this technology allows a diagnosis more precise, since the images obtained are the result of echoes transmitted by body structures.

Finally, we must not forget that there are devices that use this technology to scare away aggressive animals.

These sound waves were detected in the 18th century when the strategy of bats to catch their prey. The study of light in movement in the 19th century it was instrumental in understanding ultrasound waves. The use of the tuning fork as a tuning element for musical instruments was decisive in understanding this

dimension sound. Dolphins and whales are the animals with the most capacity when it comes to capturing this modality of sounds and this is possible because they have a unique capacity among living beings, the echolocation.

Infrasound and its applications

When we are below the audible spectrum we are facing an infrasound phenomenon. These sounds have some characteristics: they are emitted by spherical waves, if the frequency is high, there is less absorption and they are waves that can reach a greater distance. These non-audible acoustic waves have a structure similar to light rays and this means that they can travel very long distances without losing their Energy.

In the animal world some species use this acoustic strategy to establish some type of communication (For example, elephants detect these sounds because their hearing aid allows them to pick up on the low frequency of these vibrations.)

Some natural disasters generate major catastrophes but, paradoxically, they are not audible (this is what happens with avalanches, Volcanic eruptions or ocean waves).

Our body emits infrasound and, although they are imperceptible from an auditory point of view, they can cause alterations and states of anxiety. Some events that provoke panic reactions are related to this acoustic phenomenon.

Fotolia photos: Katsiaryna / Romaset

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