Psychoacoustics against the enemy. Suppression system AHAD (USA)
The USA continues to develop non-lethal acoustic suppression systems for use in various fields. A new sample of this kind, the AHAD product, is distinguished by its small dimensions and ease of use, as well as an original principle of operation. Unlike other acoustic weapons, it does not hurt, but it also seriously affects the target.
Perspective development
For the past several years, the Naval Surface Warfare Research Center, Crane Division, has been working on the topic of non-lethal acoustic equipment. The main result of such work at the moment is the AHAD (Acoustic Hailing And Disruption) system.
AHAD research and design was completed about two years ago. In December 2019, NSW and the US Department of the Navy filed a patent application for "Handheld acoustic hailing and disruption systems and methods." In June of this year, the invention was secured by the patent US20210195306A1.
The document describes the design of the suppression system and the general principles of its operation. It also includes graphic images of the assembled product and individual components. Photos of a real prototype of AHAD were also published, on the basis of which drawings for the patent were made. They allow you to consider the design in more detail.
According to published data, the goal of the AHAD project was to create a fundamentally new non-lethal speaker system. It should act on the speaking or screaming person and silence him without resorting to pain. The solution to such a problem is provided due to a specific psychological and acoustic effect.
It should be noted that AHAD is not a completely new development. So, about 10 years ago, a Japanese-designed Speech Jammer Gun appeared on the civilian market. This device used the same principles of operation and could affect people within a radius of several meters. Later, there were applications for smartphones with similar functions.
Design features
The patented AHAD system is a portable device of limited weight and size. It is distinguished by a rather rough execution. The purpose of the prototype was only to demonstrate the original technology, and was not required of convenience or high performance. In the future, it is possible to create new options that are more convenient to use and even compatible with any media.
The AHAD prototype is based on a simple frame to which all other devices are attached. A microphone is installed at the front end of the frame; for more efficient operation, it is turned back, away from the target, and is complemented by an acoustic mirror. With the help of the latter, sound waves are collected and reflected on the microphone.
A signal processing unit is directly connected to the microphone. It is he who is responsible for the formation of "disturbing" sounds, and the performance of the entire system depends on him. The case under the frame houses the amplifier and the power supply, and its front wall is given for the installation of a directional acoustic emitter. The latter is based on 50 small speakers of the required power.
In the main operating mode of the device, a microphone and a mirror are used as a directional system that receives an acoustic signal from a target - a conversation or a shout. The processing unit generates a new signal: a copy of the original sound is mixed with a delay. A similar signal goes to an amplifier and is output to a directional emitter. The operator can control the volume of the system and the delay of the auxiliary audio signal.
If required, AHAD can operate as a conventional directional loudspeaker. In this case, the signal from the source goes directly to the amplifier, without additional processing.
Psychoacoustic effect
Normally, the speaking person perceives his voice due to the vibrations of the air and due to the conduction of the tissues of the head. At the same time, sounds reach the ears with a slight delay, but the brain quickly learns to ignore it and begins to perceive its own voice normally. Reflection of sound from surrounding objects and echoes with a longer delay interfere with normal perception. This effect can be seen in large rooms with good reverberation.
It is this phenomenon that is used by the AHAD system. A person who is talking or screaming under the influence of a directional microphone and loudspeaker hears his / her voice twice at a certain interval. Tests have shown that most of the "experimental" while experiencing discomfort, lose their thoughts and can not continue the conversation. The best results are achieved with a delay equivalent to one syllable in the speaker's speech.
The use of directional acoustic means allows the use of AHAD against a specific target. Only the speaking person will experience unpleasant sensations, while those around them will only notice a slight change in sounds and acoustic background. However, the "defeat" of the chosen target is also not guaranteed. Often, the subjects noticed a strange echo, but continued to speak. At the same time, no negative phenomena were noted.
Thus, AHAD in its current form has only limited effectiveness, and the potential of the product against a specific “target” is impossible to predict. The developers of the system believe that it is not yet ready to go beyond the laboratory and needs further research and improvement. At the same time, they cannot even name the approximate dates for the completion of work and the appearance of a full-fledged "combat-ready" product.
Practical potential
The architecture of the AHAD system lends itself to scalability without any special difficulties and allows you to create portable or portable products with different levels of technical characteristics. Accordingly, a potential operator gets the opportunity to order a system with the required parameters or choose a ready-made sample.
An acoustic “hail and break” system can be useful in suppressing riots and dispersing crowds. In such a situation, the AHAD operator must follow the crowd, look for the most active participants and literally silence them. Without the ringleader, the crowd will be less active.
However, the actual effectiveness of suppression in such a situation may be limited. Thus, an “activist” may be immune to the effects of AHAD. In addition, he can wait and return to his previous occupation - and demand a new impact. In addition, the situation during the riots is not always conducive to tracking down individuals.
The military use of AHAD is questionable. In a typical clash, there are simply no episodes in which the enemy could be influenced by his own voice. Only a directional loudspeaker of a new type has real prospects in the context of the army. The need for signal processing and microphone processing is questionable.
However, the suppression system can also be used in combat. In such an environment, AHAD should be directed at enemy gunners. Then they will hear not only shots from the other side, but also their own, and twice. Perhaps such an illusion of increased shelling can scare the enemy and affect the outcome of the battle.
With ambiguous prospects
Thus, one of the leading research organizations of the US Navy has studied the well-known psychoacoustic effect and developed its own version of the device for its practical application. The general characteristics and capabilities of this product have already been confirmed through tests, but the practical prospects are unclear.
It should be noted that the experimental AHAD system appeared two years ago, and at the same time the achieved level of the project made it possible to file a patent. Therefore, it cannot be ruled out that over the past time NSW has carried out new work and received certain results that fundamentally allow implementation in practice. However, a negative scenario is also possible with the termination of work due to the lack of real prospects. Whether the recent patent remains the only achievement of the AHAD program will become clear later.
- Ryabov Kirill
- US Navy/Naval Surface Warfare, Crane Division
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