Title: Directional Square Dance Speakers: Low-End Directional Energy to Improve the Problem of Disturbing People**Recently, have you noticed that square dancing near the neighborhood doesn't seem to be as noisy as it used to be?If that's the case, you've probably discovered a low-end version of directed energy**. Square dancing has long been regarded as a major nuisance.
Especially when resting, those ** who move times begin to drill into their ears indiscriminately, making people more and more irritable the more they listen. However, after all, square dancing is an entertainment activity for ordinary people, so the extreme measures of confrontation with the aunts and uncles who dance square dances often exacerbate the contradictions, and even lead to the consequences of outweighing the losses.
So, how do you fix this?We all know that sound travels through the air. Generally speaking, when a sound source vibrates, the sound waves travel along the air. This also explains why when a place dances in a square, the surrounding neighbors find it noisy.
The best way to solve the problem of square dancing is to let the sound reach only the people who need to hear it. It has been reported before that aunts and uncles wear headphones to dance square dances to avoid disturbing the people, but they dance square dances to be uninhibited and free, so wearing headphones seems to be contrary to their original intention.
That's where directional square dance speakers come in handy. At present, there are three main technical means that can realize the directional transmission of sound. The first is the sound condenser technology, which is to install a hemispherical cover on the tweeter to block the free spread of sound waves. Sound can be heard clearly under the hood, while outside the hood is barely audible.
The shape of such a device is very similar to that of a desk lamp lamp. The second is speaker array technology, that is, a large number of speakers are first formed into an array, by extracting the sound signal of each speaker, and combining these signals in a certain way, and finally processing the signal to enhance the sound signal of a specific position or a specific direction.
This technology is commonly used in devices such as sonar, radar, etc. The third is an ultrasonic-based directional audio frequency propagation technology, which is a new type of audio technology that can make sound travel in a certain direction in the form of a beam.
The basic principle is to modulate the sound to the ultrasonic wave through intelligent means, and then emit the sound wave into the air through the ultrasonic transducer. As ultrasonic waves of different frequencies propagate through the air, they interact and demodulate nonlinearly, and new sound waves are generated with frequencies that are the difference between the original ultrasonic frequencies (differential frequency).
Ultrasound has the unique property that when the newly generated differential frequency sound wave falls exactly within the audible range, combined with its high directionality, it can precisely transmit this new sound wave to a specific object.
This technology allows people in the directional area to hear clearly**, while in the non-directional area, the sound is rapidly diminished so as not to disturb others. This simple and reliable technology works very well. So, how do you turn this technology into directed energy**To explain this, we have to go back a long way.
In 1929, the Leerick Theatre in London, England, staged a play that went back 150 years. To make the audience feel like they were there, the director turned to experimental physicist Robert Wood for help.
Wood used the organ pipes to create a deep, sustained sound, and as a result, the sound of the organ pipes caused the glass on the chantels to rattle and the doors and windows to squeeze, causing the audience to feel uneasy and panicked, and the performance had to be called to an emergency halt. This effect arose because Wood created infrasound.
There are countless sounds in nature that are "inaudible to the human ear", such as the wind blowing leaves, the waves crashing on the shore, lightning and thunder, etc., which may produce sound wave vibrations with a frequency of less than 20 Hz, which are infrasound.
Due to the extremely long wavelength of infrasound waves, diffraction occurs when infrasound waves encounter obstacles, and its influence is extremely wide, and infrasound waves below 10 Hz can travel thousands of kilometers away. For example, in 1983, the eruption of Mount Karakato in Indonesia caused strong sound waves to circle the earth three times and last for 108 hours before gradually disappearing.
In addition, infrasound waves are not easily attenuated and are not easily absorbed by water and air.
Because the frequency of infrasound waves is close to the natural vibration frequency of the nervous system and various organs of the human body, when infrasound waves resonate with the human body, it will lead to dysfunction, displacement and deformation or fibrillation rupture, making people have difficulty breathing, blurred vision, nervous disorders, loss of consciousness, shock and fainting and even death.
During World War II, Nazi Germany secretly developed infrasound** in an attempt to destroy entire cities using resonant reactions, but ultimately failed.
In the 40s of the last century, the German army produced a batch of records with built-in infrasonic waves and the signature of famous ** artists, which were planned to be put into Britain to create panic, terror and other mental disorders, causing riots. However, the results of this plan have not been satisfactory.
Infrasound**, which really entered the practical stage, was developed by Vladimir Gavreo of France. He led the team to develop robots capable of dealing with nuclear war in the 50s of the last century. In one experiment, they found that when the frequency of sound waves emitted by the laboratory motor was below 20 Hz, they resonated with human organs, causing discomfort to the human body.
For example, the resonance frequency of the heart is about 6 Hz, 40 to 100 Hz for the eyes, 20 to 30 Hz for the head, 2 to 5 Hz for the arms, 2 to 3 Hz for the stomach, 2 to 4 Hz for the intestines, and 0 for the vestibular organs5 to 13 Hz.
When a person is in the range of infrasound, the human organs will begin to vibrate and further amplify and enhance their own oscillation amplitude.
Therefore, from the mid-60s of the 20th century, he focused on the secret research and development of sonic **, and finally successfully developed the first infrasonic generator in 1972, which was also classified as top secret by the French side at that time.
However, it was not until April 1986 that due to technical negligence, infrasonic waves rushed out of the laboratory outside Marseille, France, causing 20 people indoors 16 kilometers away and 10 people working in the field to lose consciousness at the same time and die of a ruptured cerebral blood vessel. This secret was only known to the world, and countries began to develop sound waves.
In addition to infrasound**, strong sound**, ultrasonic**, noise**, and cluster sound pulses** have also been developed according to the frequency range corresponding to sound waves. Strong sound waves** are mainly used for short-term deterrence, which can cause palpitations or incapacitation, but cause less long-term harm to the human body.
Ultrasound** uses the powerful sound pressure or acoustic thermal effects generated by high-energy ultrasound waves to impact or injure a person. Noise** uses high decibel noise to stimulate and affect people's physical and mental state, making people irritable, and even dizzy, tinnitus and psychological panic.
Cluster acoustic pulses** can use fluid compression technology to endow sound waves with high-energy characteristics, and the power is even more amazing. In 1995, the United States allegedly carried out a covert infrasonic attack on Serbian positions in Bosnia and Herzegovina, causing Serbian soldiers to faint, vomit and fall into confusion within seconds.
In 2000, after the USS Cole was attacked by a suicide boat, the United States developed the LRAD (Long Range Acoustic Device) directional acoustic wave device as one of the ship's near-zone defense systems.
Such a device is capable of directing 150 decibels of noise at an angle of 15 or 30 degrees to a target area tens or even hundreds of meters away, which is equivalent to putting the enemy under the turbofan engine of a jet airliner. LRAD is capable of inflicting extreme suffering and incapitating combat on the enemy, and can even immediately incapacitate forced personnel.
Its propagation range can reach hundreds of meters, while the range of high-power LRAD can reach 3-9 kilometers. At the same time, the United Kingdom has also developed an ultrasonic** for use as an underwater frogman protection system, which can generate a strong sound pressure shock wave in the water to detect and deter intruding frogmen.
With the popularization of the concept of directional sound wave and the expansion of application fields, the application of directional sound wave as an acoustic deterrent method is becoming more and more extensive. As an industrial power, China has naturally made continuous progress in this field.
Recently, the China Coast Guard released an official information saying that the Chinese Coast Guard has implemented control measures in accordance with the law on three Philippine Fisheries and Aquatic Resources Bureau official vessels that intruded into the waters adjacent to Scarborough Shoal in the Spratly Islands.
* It shows that the Chinese coast guard ship used water cannons to drive away the Philippine vessel, but in fact, the Chinese coast guard also used a long-range directional sound wave dispersion device on the Philippine vessel, which amplified the noise to 160 decibels, far exceeding the 100 decibel hearing limit of the human ear, and can use sound waves to interfere at a distance of 3 kilometers. This is not new equipment.
According to the People's Liberation Army Daily, as early as 2010, directional sound waves were used on the escort ships of the fifth batch of escort formations of the Chinese Navy**. The structural principle of directional acoustic wave is not complicated, and it is generally composed of signal processing circuits, power amplifiers, transducers and control circuits.
The signal processing circuit is responsible for modulating the input audio information, the power amplifier is responsible for amplifying the modulated electrical signal, the transducer is responsible for turning the amplified electrical signal into a sound wave signal and transmitting it, and the control circuit is responsible for the control of the whole system.
In recent years, domestic enterprises have invested in the research and development and production of directional acoustic equipment, although this equipment is more complex in design, but there is no technical threshold. It is widely used in the field of military and police in anti-terrorism and riot control, warning, dispersal, strike, airport bird repellent, maritime surveillance and law enforcement.
In addition, some manufacturers have also combined directional acoustic wave dispersion equipment with infrared, thermal imaging, monitoring, radar and other perception systems to create a control platform integrating monitoring, early warning and dispersal strikes. In addition to the military and police fields, directional acoustic wave equipment is also used in bridge collision avoidance, emergency rescue, traffic guidance and other fields.
Even some hydropower reservoirs are equipped with directional acoustic dispersion equipment to drive away illegal fishing.
In order to expand sales, some manufacturers have transformed the directional sound wave drive away equipment into sound wave directional broadcasting equipment, which has a wider range of applications, from square dance directional sound to museum ultrasonic directional speakers, school playground directional broadcast systems, high-speed directional speakers, digital signage sound directional communicators, etc., all reflect its multi-functional applications.
Technology proliferation is inevitable, and people will always find unexpected application results. Just as the U.S. military did not expect that the equipment used to prevent suicide boats would be used as entertainment facilities by Chinese aunts, the diffusion of this technology is also one of the symbols of national strength.