Electronic Warfare Part 2
A variety of high powered sonic weapons (SW) exist spanning the infrasonic, ultrasonic, and audible ranges. Because they are weapons which direct sound onto a target, and sound is energy, they can be considered directed-energy weapons.
These weapons produces both psychological and physical effects. They include highly directional devices which can transmit painful audible sound into an individual’s ear at great distances and infrasonic generators which can shoot acoustic projectiles hundreds of meters causing a blunt impact upon a target.
Infrasonic generators can cause negative emotions such as fear, anxiety, or depression, as well as biological symptoms like nausea, vomiting, organ damage, burns, or death—depending on the frequency and power level.
Most of these weapons function between the frequency range of about 1 Hz to 30 kHz. These frequencies occur within the following waves: Extremely Low Frequency (ELF) 1 Hz to 30 Hz, Super Low Frequency (SLF) 30 Hz to 300 Hz, Ultra Low Frequency (ULF) 300 Hz to 3 kHz, and Very Low Frequency (VLF) 3 kHz to 30 kHz.1
Within the ELF region of the spectrum, there is a type of sound calledinfrasound, which occurs between 3 and 20 Hz. Infrasound is usually not heard, but it can be if the power level is sufficient.
Next, audible noise begins for most people from about 20 Hz up to 20 kHz, and occurs between the upper ELF into the VLF ranges. Ultrasound, begins in the VLF range at about 20 kHz, just above human hearing.
Another sound factor is power, usually described using a unit of measurement called a decibel. Decibels are used to measure the power of audible and inaudible sound, both of which produce effects.
Any sound begins to become physically painful at about 120 decibels, although at lower levels it can cause discomfort. At about 130 decibels it becomes unbearable. In this chapter, words such as intensity, level, power, pressure, and decibel, are all used to describe sound power.
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