Sound can have various physical and psychological effects on people. There are different types of sound waves, including infrasound and ultrasound. Also, there is a question – Can Infrasound and Ultrasound Damage Your Hearing?
Infrasound and ultrasound, although sounding similar, are very different in nature. Infrasound is sound that is below the lower limit of human hearing, below 20 Hz, and ultrasound is above the upper limit of human hearing, above 20,000 Hz.
The average human range of hearing is between 20 and 20,000 Hz (A Hertz (Hz) is a unit of measure for frequency and is the same as cycles per second).
This type of intense sound wave is in our environment that we cannot hear. We can detect low-frequency sound waves or infrasound in wind farms and ventilators. This type of sound is capable of producing symptoms similar to motion sickness.
Infrasound puts you at risk of neuro-sensory deafness and other illnesses caused by audible noise. However, the main effect of infrasound is that these sound wavelengths make it extremely difficult for you to focus on anything.
This type of sound waves has minimal effects on human health unless you have direct contact with the sound source. Therefore, it is quite challenging to experience hearing loss as a result of ultrasonic sound waves.
The ultrasonic sound can cause feelings of nausea, fatigue, headache, and sensations of fullness inside the ear. Ultrasonic sound produces energy that can cause heating and cellular disruption in case the sound source comes in contact with a person.
Ultrasound is sound wavelengths with frequencies above 20,000 Hertz. On the other hand, infrasound is sound waves below 20 Hz. Many countries have used infrasound in sonic warfare since the First World War. These sound waves have also been used in acoustic imaging in radar and sonar technology. Also, they are used by some animals to communicate.
Common Uses of Infrasound
Infrasound originates from both natural and synthetic sources. Infrasonic waves have very small attenuations. Therefore, they can propagate over significant distances. Many animals, including elephants, whales, and giraffes, use these waves to communicate.
Natural sources of infrasound include earthquakes, volcanoes, avalanches, waterfalls, and ocean waves. Artificial sources of infrasound include airplane engines and chemical and nuclear explosions.
Infrasound includes extreme bass and vibrations with frequencies below the audible range of the human ear. Even though when we can’t hear the pressure waves of infrasound, we can feel them.
Sound design became a reality with the invention of the doubly surround sound. Dolby systems are incredibly useful in minimizing the hiss associated with optical tracks, which allows for higher sound fidelity and subtle movie sounds.
Infrasound is mainly used in horror films to create certain feelings in moviegoers. Many people have high fidelity music systems that produce infrasound; you cannot hear the sound, but you can feel it. The infrasound produced by specific sound systems creates the perception that fits the environment and context of the movie you are watching.
The ultrasonic sound can heat body tissues through rapid vibration. On the other hand, infrasound can cause various physical and psychological symptoms, including headaches, fatigue, annoyance, increased palpitations, and nausea.
Audio Systems – Infrasonic Filters
Many modern amplifiers feature an infrasonic filter. This significant feature helps to block sound frequencies that are below the tuning frequency. It’s particularly important in ported enclosures that do not provide much control in subwoofer excursion.
When the air in a port unloads, it produces a sound like the one you hear when you are in a giant hole. As the sound continues to unload, it puts your subwoofer at serious risk of bottoming out. The infrasonic filter helps to prevent inaudible sound frequencies from becoming reproduced, which also prevents air from unloading and destroying your subwoofer.
If you decide to use your amplifier with a ported subwoofer, consider turning the infrasonic filter on. Some amplifiers feature the infrasonic filter with the fixed center frequency. In such cases, you only need to turn on the filter to prevent the reproduction of harmful low-frequency sounds. Other amplifiers have an invariable infrasonic filter. In such cases, it is advisable to set the frequency below the tuning frequency of the ported subwoofer.
Infrasonic filters are often used with subwoofers in sealed enclosures. Setting the right volume on the sealed enclosure eliminates the possibility of the port unloading at low frequencies. To minimize distortion and enhance the efficiency of your subwoofer system, it is advisable to set the amplifier power and subwoofer excursion within the range of audible frequency.
Detection of Natural Disasters
Scientists use specific sensitive instruments to detect natural disasters such as earthquakes and volcanic eruptions. Infrasound is the opposite of ultrasound, which is the high-frequency sound that dogs can hear but humans cannot.
We can measure the sound frequencies in Hertz. Humans can discern sounds within the range of 20 Hz to 20000Hz. Infrasound signals are less than 20 Hz. While ultrasound has a short-range, infrasound can travel long distances. For instance, when the Krakatoa erupted in 1883, its infrasound waves went more than three times around the earth.
Scientists are now trying to use infrasound-detecting instruments to detect natural disasters such as tornadoes and earthquakes. The instruments have also been installed in mountainous regions such as in the slopes of the Rockies to detect avalanches before they happen.
Communication – Animals
A notable feature of infrasound is that some animals use it to communicate, especially in places with low visibility. Animals such as rhinos and giraffes use infrasound to detect phenomena in their environment and communicate with each other.
Elephants are animals that conclusively demonstrate how animals use infrasound to signal each other. Their infrasonic rumbles that can cover quite a large area and can be sensed by other elephants over distances of about 30 square kilometers under poor atmospheric conditions and over 300 square kilometers under ideal conditions.
Common Uses of Ultrasound
Ultrasound is used in scanning to provide images of developing fetuses inside their mothers’ wombs. Ultrasound scanning works by directing sound waves towards the subject. Once the sound waves hit the subject, it reflects the waves to a detector that sends electrical signals to a computer. The computer uses the electrical signals to display an image on a screen.
Many filmmakers use ultrasound to create an unnerving effect on people intentionally. Sound constitutes pressure waves that move through the air at specific frequencies. The higher the frequency of the pressure waves that higher the pitch of the sound when it finally reaches the eardrums.
The brain interprets sound frequencies according to the number of pressure waves that your eardrum senses each second. For instance, a whistle produces sound pressure waves that oscillate at a relatively high frequency resulting in a high-pitched sound. On the other hand, a truck engine produces pressure waves that oscillate at a low frequency resulting in low-pitched sound.
However, our sensitivity to sound degenerates as we age. Therefore, younger people are capable of hearing sound waves that older ones cant. Although some sound waves are inaudible, they can be felt and can produce feelings of chills, sorrow, and anxiety.
The most common use of ultrasonic sound waves is ultrasound therapy. This involves using high-frequency sounds to transfer heat to certain parts of the body.
Therapeutic ultrasound is used primarily for two different effects: the deep heating treatment and non-thermal uses.
Deep Heating Effects:
Ultrasound is often used to provide deep heating to soft tissue structures in the body.
It is believed that deep heating tendons, muscles or ligaments increases blood circulation in those specific areas.
Majority of physical therapists use ultrasound to help improve or increase the extensibility of tissues around someone shoulders if they have been diagnosed with a frozen shoulder.
Non-Thermal Effects (Cavitation):
Ultrasound introduces energy into the body. This energy causes microscopic gas bubbles around your tissues to expand and contract rapidly, a process called cavitation. It is theorized that the expansion and contraction of these bubbles help speed cellular processes and improves the healing of injured tissue.
Two types of cavitation include stable and unstable cavitation. Stable cavitation is desired when your physical therapist is applying ultrasound to your body. Unstable cavitation can be dangerous to your body’s tissues, and your physical therapist will ensure that this does not occur during the application of ultrasound.
Contraindications to Using Ultrasound
There are some instances where you should not use ultrasound at all and these include the following:
- Over metastatic lesions
- Over areas of decreased sensation
- Over parts of the body with metal implants
- Like in a total knee replacement of lumbar fusion
- Near a pacemaker
The effects of Ultrasound technology have been proven to have many effects on fetal bodies.
In Australia, a study conducted on 1,400 pregnant women. It showed that women who had five monthly ultrasound tests, as compared to women who only had one throughout the entire pregnancy, gave birth lower weight babies overall. Another conclusion from this study showed that the babies that were exposed to ultrasound were mostly left-handed.
Contraindications to Using Infrasound
Infrasonic sound waves have many effects on hearing.
The sound waves are capable of altering sensory cells in your ears and their sensitivity. Infrasonic waves can subconsciously cause to hear certain noises even when there is no audible noise.
The sound waves can cause the liquid-filled sections of the ear to swell, which may lead to vertigo and tinnitus. Infrasonic sound waves are uncomfortable to humans, and long-term exposure may lead to noise-induced hearing loss.
While the most apparent effects of infrasound on humans are discomfort and annoyance, it can also cause physical effects. It is often associated with breathing and digestive problems, especially in people who live close to wind turbines.
What’s the Difference between Infrasound and Ultrasound
An exciting characteristic of infrasound is that they travel long distances, sometimes around the globe, without losing their strength. It means that we can use certain instruments to detect infrasound in many parts of the world without actually being where the sound originates. For instance, an infrasound-detection device in California can detect infrasound from a nuclear reaction in Pakistan or the Korean Peninsula. However, a problematic aspect of measuring infrasound is that it requires sensors that cover large areas because infrasound wavelengths are quite long.
Infrasound plays critical roles in detecting sudden stratospheric warming. This weather phenomenon is associated with the extreme cold. This has been experienced in various parts of the world, including the Netherlands and Scandinavian countries. Sudden warming of the stratosphere is a typical trait of winter in the northern hemisphere.
Infrasound is pressure waves below 20Hz. These sound waves are inaudible by humans, but some animals are capable of hearing infrasound. There are various uses of infrasound, including detection of natural phenomena such as earthquakes, volcanic activities, and avalanches. Although humans are incapable of hearing infrasound, we can feel it in certain instances. Many people describe infrasound as the sound that you cannot hear but can feel.
On the opposite side of the sound spectrum is ultrasound, which includes the normally audible sound that humans can hear. Ultrasound waves range between 20Hz and 20000 Hz. While infrasound cannot damage hearing, it can have various physical and psychological effects, including annoyance and nausea. However, excessive and prolonged exposure to high-frequency ultrasound can be detrimental to hearing.
As we have seen, both technologies: Ultrasound and Infrasound have got many benefits uses.
Your physical therapist may use ultrasound to help improve your condition. Not only that, scientists can use infrasound-detecting instruments to detect natural disasters such as tornadoes, earthquakes. The best thing is that they can inform people to take proper precautions, thus saving millions of lives.
Each of these technologies has got its unique contraindications. You should be familiar with them so that you can take proper precautions to protect yourself.