LRAD And Sonic Defence

Recent studies into other forms of weaponized sound projection systems such as the long range audio device (LRAD) which can projects sound in a beam hitting a small target area rather than an area around the device like a normal speaker.

The LRAD is designed for the normal hearing frequency range of the human ear, but with the volume reaching 160 decibels it can cause hearing loss, modification out of the range of human hearing can also be dangerous.

Knowing that noise cancelling foam can cancel out around the audible range and subsonic frequencies, it surprised me to learn that cardboard can be more effective at nullify the sound of the LRAD better than noise foam

Even though noise canceling foam is designed for the human hearing range in frequency as it is used in music studios to cancel out sound, the sound produced by the LRAD can bypass noise foam.

Sound itself is a small range of frequencies and small range in decibels, when the decibels are to low the sounds can not be heard.

When the decibels are increased to a high level it can cause damage to the ears effecting hearing negatively.

Permanent damage depending on time of exposure and levels of volume in decibels, the higher the decibels the shorter the time until damage is noticeable, long exposure to high decibels that are not instantly damaging can still cause damage over time, the effect of damage can be noticed as ringing in the ear known as tinnitus.

Volume is measured in decibels and is the pressure of each wave, the frequency is how often between each wave, and as the decibel increases the air pressure become a heavy force of compressed air that can push objects.

The frequency is how rapid the pulses are in air pressure, a person can feel lower bass frequency, and can feel a frequency that is lower than the range of hearing, this is known as subsonic.

In the low frequency range, at a very high  level of decibels the pressure wave can feel like a thump, and at extremely high levels of decibels it can reach a pressure close to an explosion.

High level of frequency above the frequency range of hearing can cause high levels of vibration of an object around it, this can cause friction and fracturing of objects.

Everything has a unique natural frequency and if the frequency of an objects resonates with a projected frequency, the object can vibrate while other objects around it remains still.

A frequency can be tuned to effect individual materials, and at high frequencies in the ultrasonic range can cause burning of flesh and micro fracturing of bone due to the high speed of the vibration.

The less flexible and more denser the object the more likely the pressure wave can pass through object but is more likely to cause micro fracturing or shattering of that object the more softer the object the more likely to disperse the energy in the form of heat due to the friction on an atomic scale.

Pockets of vacuumed insulation stops pressure passing through objects by removing the atoms that sound travels through altogether, but can collapse in under high pressure.

Different layered materials that resonates at different frequencies surrounded with a buffer can help with dissipating the energy, and can help cancel out subsonic and ultrasonic frequencies, higher frequency require highly smoother materials to nullify, lower frequency require rougher materials.

Under the United Nation Charter energy weapon use is illegal, and in the United Kingdom LRAD are illegal, under certain configurations the LRAD is considered illegal when using excessive decibels or certain harmful frequencies, in the United States Of America the LRAD has to configured to the human hearing range and can not be above a certain level of decibels.

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