Infradźwięki

Prepare answers to the following questions.

1. What is a sound wave?

2. List the features of the sound.

3. What is the range of audible frequencies?

Can you hear infrasoundinfrasoundinfrasound?

Infrasound that is part of the noise is not audible. But it is picked up by the body, in a specific way, through the auditory path (mainly through hearing organs). The audibility of these infrasound is dependent on the sound pressure level.

Some animals, such as elephants and whales, can communicate with each other using infrasound.

Indicate the natural sources of infrasound.

The natural sources of infrasound are:

• earthquake,

• eruption of volcanoes,

• auroras,

• ocean waves,

• hurricane wind,

• sinking of masses of water from large waterfalls.

Indicate the artificial sources of infrasound.

Artificial sources of infrasound generated by man.

Infrasound can be encountered in large office buildings, industrial buildings.

The source of this infrasound are machines and devices. Ventilation and air conditioning ducts strengthen these soundssoundssounds.

Infrasound is generated by:

• vibrationsvibrationsvibrations of bridges,

• operation of wind farms,

• work of jet engines,

• explosions.

RGxNP9k4ufXMl

pokaz multimedialny - podział dźwięków na infradźwięki, słyszalne oraz ultradźwięki. Instrukcja obsługi z poziomu klawiatury: 1. Uruchomienie aplikacji - ENTER, 2. Na każdym ze slajdów czytany jest automatycznie tekst alternatywny po polsku, 3. Przy pierwszym uruchomieniu na pierwszym slajdzie, czytanie tekstu po angielsku - TAB, 4. Przejście między slajdami: do następnego slajdu - TAB, do poprzedniego slajdu - TAB + SHIFT, 5. Przejście do czytania napisu po angielsku - strzałka w górę + strzałka w dół (czyta tekst po angielsku widoczny na slajdzie).

pokaz multimedialny - podział dźwięków na infradźwięki, słyszalne oraz ultradźwięki. Instrukcja obsługi z poziomu klawiatury: 1. Uruchomienie aplikacji - ENTER, 2. Na każdym ze slajdów czytany jest automatycznie tekst alternatywny po polsku, 3. Przy pierwszym uruchomieniu na pierwszym slajdzie, czytanie tekstu po angielsku - TAB, 4. Przejście między slajdami: do następnego slajdu - TAB, do poprzedniego slajdu - TAB + SHIFT, 5. Przejście do czytania napisu po angielsku - strzałka w górę + strzałka w dół (czyta tekst po angielsku widoczny na slajdzie).

Zasób interaktywny dostępny pod adresem https://zpe.gov.pl/a/D5eSPgTsH

Introduce the properties of infrasound.

Properties of infrasound:

• They spread very well in the air and over long distances. There is practically no change in the intensity of infrasound.

• Infrasound disperses at the speed of sound waves.

• Infrasound is not suppressed by acoustic screensacoustic screensacoustic screens or their attenuation is very small.

• People cannot hear infrasound, but they can feel it. Infrasound effects on the human body are very unpleasant, infrasound is dangerous at high volumes.

• InfrasoundinfrasoundInfrasound can cause feelings of anxiety and fear. The effect of infrasound is nausea and headaches. They disrupt the sense of balance. Due to the lack of advisability to build shields to protect against infrasound, they arouse interest in military use. Of course, these tests are classified.

• Some animals can hear infrasound and they use it to communicate at very long distances. Among them there are giraffes, elephants and whales.

Summary

InfrasoundinfrasoundInfrasound - these are acoustic waves (soundssoundssounds) with frequencies between 0,1 and 20 Hz. They are inaudible to human beings. In natural conditions they arise, during explosions, lightning, earthquakes and, for example, waves of water. At an appropriate high sound pressurepressurepressure level, they have a negative effect on humans. They cause concern and nausea, and even states of depression, etc. Infrasound is picked up not only by the ears but also by vibration receptors, for example on the skin or in tendons, muscles and joints. These sounds at such a low frequency may cause resonanceresonanceresonance vibrations, in particular, in the chest, throat or abdominal cavity.

Exercises

Glossary

Keywords

frequencyfrequencyfrequency

infrasoundinfrasoundinfrasound

sound propagationsound propagationsound propagation

soundssoundssounds

wavelengthwavelengthwavelength