Volume 29, Issue 1, January 2026, Pages 14-20
Injury of sonic weapons to human body: A narrative review
Author links open overlay panelYue Li a,
Guangming Yang b, Yongbo Zhao a, Bingcang Li b
1. Introduction
Sonic weapons are a type of non-lethal weapon that has increasingly received attention from people in modern warfare for their effects and
injuries to the human body. Sonic weapons can be divided into infrasonic weapons, intense sound weapons, and ultrasonic weapons based on their frequency. Scientists in China have previously reported on the concept of infrasonic weapons,
1,
2,
3,
4,
5 infrasound field characteristics,
6 infrasound focusing and targeting,
7,
8 psychological effects of infrasound,
9 biological effects of infrasound,
10,
11,
12the influence of infrasound on the
central nervous system and neural-psychological aspects,
13 military applications of infrasound,
14 and physical protection against infrasound.
15For intense sound weapons, Chinese scientists have introduced its concepts and applications,
16,
17,
18,
19,
20 the biological effects,
12,
21 and the effectiveness evaluation system.
22,
23,
24 However, there are relatively few literature reports on ultrasonic weapons, with only sporadic reports on the physical characteristics of ultrasound
12,
21 and the basic principles of ultrasonic weapons.
17
Given the lack of comprehensive and systematic research on the damage to the human body caused by sonic weapons and their prevention and treatment in previous reports, this article retrieves Chinese and English literature published from January 2000 to January 2024 through databases of SinoMed, CMCI, PubMed, Embase, Web of Science, as well as search engines such as Baidu Scholar and Microsoft Bing by using the keywords acoustic weapons, sonic weapons, infrasonic weapons, intense sound weapons, ultrasonic weapons, noise weapons, and prevention and treatment. The literature inclusion criteria were as follows: (1) literature collected from medical databases and internet search engines, and (2) original research papers and research reports. The literature exclusion criteria were: (1) literature that could not be accessed in full text or was not in Chinese or English; and (2) science-promoting papers. Finally, 24 Chinese and 32 English articles were included. The aim is to provide references for future development, protection, and medical treatment of acoustic weapons.
2. Acoustic concepts
2.1. Sound frequency
The number of vibrations per unit time by a sound source is known as sound frequency, also referred to as audio frequency, measured in hertz (Hz). Infrasound frequencies range from 0.001 to 20 Hz. Although infrasound is generally inaudible to the human ear, it can still be sensed and, at sufficiently high power levels, can be heard.
25,
26 Infrasound is commonly present in various industrial, transportation, and living environments, also generated by phenomena such as nuclear explosions, rocket launches,
9,
13 as well as natural occurrences like earthquakes, volcanoes, tornadoes, and waterfalls.
27,
28 Animals such as crocodiles, elephants, giraffes, and whales can use infrasound for long-distance communication.
27,
28Infrasound has long wavelengths, such as 5 Hz for 68 m and 7 Hz for 48.5 m.
22,
29Frequencies ranging from 20 Hz to 20 kHz are audible sounds, with the human ear being most sensitive to frequencies between 1 kHz and 3 kHz.
25,
26,
27 Ultrasound refers to frequencies higher than 20 kHz, which are inaudible to the human ear, but can be heard by dogs, cats, turtles, and bats. Also, whales and dolphins use ultrasound for prey detection.
25,
26,
27 Ultrasound is highly directional and can penetrate the body, allowing for medical
imaging techniques to obtain structural information of internal organs.
30 Sound frequencies can also be categorized as low-frequency (<400 Hz), mid-frequency (0.4–1 kHz), and high-frequency (>1 kHz).
31 Both infrasound and ultrasound can induce resonance in the human body.
25
2.2. Noise
Noise refers to sounds that are irritating, excessively loud, and detrimental to
human health. It is generated by the irregular vibrations of sound-emitting objects. Noise can be classified as steady-state noise (with fluctuations in sound level not exceeding 3 dB) and pulse noise (short duration with high and sharp amplitudes).
32 Similar to sound frequencies, noise can also be categorized as low-frequency, mid-frequency, and high-frequency.
The human
auditory system has a higher tolerance for low-frequency noise, even at high sound pressure levels (SPLs), resulting only in temporary threshold shifts (TTS) rather than permanent threshold shifts (PTS).
33,
34 Low-frequency noise ranging from 150 to 155 dB can cause chest wall vibration, slight nausea, and
dizziness. At 154–171 dB, it can lead to increased heart rate, flushing of the skin,
swallowing pain,
visual impairment, subcostal discomfort,
coughing,
sternum compression, and breathing difficulties.
33 When mid-frequency noise reaches 120 dB, it can resonate with the
nasal cavity or sinus and enhance their tactile sensation. At ≥142 dB, it can stimulate the
vestibular system, and at 165 dB, it can cause itching.
34 For high-frequency noise, TTS or PTS can be caused by SPL ranging from 80 to 120 dB, tactile sensations or itchiness can occur at 120 dB, vestibular reactions can be induced
at 125 dB, balance disorders can be caused at 140 dB, and thermal effects can be generated at 160 dB.
33 The combination of sound intensity and exposure time determine the level of damage, for example 135 dB for 7 min, 140 dB for 40 s, 145 dB for 4 s, 150 dB for 0.4 s, and 160 dB can cause perforation of the
eardrum (it is previously believed that the perforation have a protective effect on the inner ear, but human data suggests that
eardrum perforation provides no protection, whether unilateral or bilateral).
35
2.3. Acoustic power
Acoustic power refers to the amount of sound energy passing through a specified area per unit time. When measured in terms of energy, it is referred to as sound intensity, expressed in W/m2. If measured in terms of pressure, it is referred to as SPL with the unit of Pa. The indicator of SPL is in dB.25 The conversion formula between dB and Pa is given by L=20, where L is the SPL, P1 represents the sound pressure being compared, and P0 represents the reference sound pressure (often taken as 20 μPa). Acoustic power is directly proportional to the square of sound velocity, sound frequency, and amplitude. Therefore, ultrasound has high acoustic power, while explosion waves own high acoustic power due to their high amplitudes.
31 When acoustic power exceeds 120 dB, it is considered high-intensity sound, causing discomfort to the human ear and potential hearing loss. At 140 dB (200 Pa), it can be painful to the human ear, above 160 dB (2 kPa) causes eardrum rupture, and 173 dB (9 kPa) for lung rupture.
30,
33
2.4. Acoustic propagation
Infrasound and audible sound propagate at the same speed,
3 which is about 300–340 m/s in the atmosphere and 1480 m/s in water.
7,
21 The energy of sound wave undergoes attenuation and absorption during propagation, which is influenced by factors such as humidity, temperature, and pressure.
19 The rate of sound attenuation is directly proportional to the square of its frequency, so higher frequencies result in faster attenuation.
12 As a result, infrasound experiences less attenuation, allowing for long-distance propagation (thousands to tens of thousands of kilometers).
7,
21 On the other hand, ultrasound experiences significant attenuation, resulting in shorter propagation distances.
29 The penetrating power of sound waves is inversely proportional to the sound frequency. For example, 7 Hz infrasound can penetrate through reinforced concrete walls several meters thick, as well as steel plates,
seawater, and soil layers, while audible sound at 7 kHz cannot pass through a piece of paper.
14,
30
3. Infrasonic weapon
3.1. Types and applications of the weapons
Currently, there are 3 types of sonic weapons: sonic cannons, sonic bullets, and sonic guns, all composed of sonic generators, power devices, and control systems.
14 The Chinese Academy of Sciences has developed a sonic gun with a frequency less than 20 Hz.
36 The SPL of sonic guns developed by the United States (U.S.)
18 and France
20 can reach 160 dB. Infrasonic weapons can be classified into 5 categories based on their generation methods: (1) burst-type: compressed gas, high-pressure steam, or high-pressure gas is released in a pulse to excite the medium and generate sonic waves, with the advantages of small size, low frequency, and easy control, but with low sonic intensity and short range of effect; (2) explosive-type: infrasonic waves are generated by explosions, and about 50% explosive energy converts shockwaves, then decay to produce infrasonic waves; (3) tube-type: its structure and working principle are similar to a flute. Infrasonic waves are generated when the air inside the tube vibrates at the same frequency as the tube itself; (4) speaker-type: the working principle is similar to a speaker. Special diaphragms are used to generate infrasonic waves through vibration; (5) beat frequency-type: 2 sound wave generators with different frequencies are used simultaneously to generate infrasonic waves based on the difference in their frequencies.
2 Compared to intense sound weapons, the development of infrasonic weapons is more challenging, due to the technical difficulties such as it is hard to increase the power output and duration of the infrasonic generator, to reduce the size and weight of the weapon system, to make wave beam more directional and focused.
7,
18,
23
The US has secretly used infrasonic weapons in the Somali, the Bosnian, and the Gulf War. It is reported that infrasound attacks on the Bosnian Serb Army caused a large number of soldiers to faint and vomit within seconds, resulting in the loss of combat effectiveness.
20The US also suspects that its embassy personnel in Havana (Cuba) and Guangzhou (China) have been attacked by infrasonic weapons.
27,
28
3.2. Mechanism and characteristics of injury
The main characteristic of infrasonic weapons’ harm to the human body is organ resonance. When the frequency of infrasonic waves is close to the inherent frequency of human organs, the organs can absorb sonic energy at the maximum extent, thus causing damage through resonance.
13,
20 Infrasound can also convert mechanical energy into thermal, biochemical, and bioelectricity energy, thereby damaging the molecular structure of cells.
11,
20 Infrasound stimulation can disrupt the brain and cause
mental disorders, while stimulating somatosensory and visceral receptors can produce reflexive
physiological responses. Based on these, infrasonic weapons can be divided into “neurological type” and “organ type”.
12,
13,
20
Neurological infrasonic weapons have a frequency of 8–12 Hz, which is the same as the inherent frequency of the head.
15,
34 It is also consistent with the
α rhythm (8–12 Hz, amplitude of 20–100 μV, commonly seen during relaxation) of brain waves, which also has
β rhythm (14–30 Hz, amplitude of 5–22 μV, commonly seen during thinking),
θ rhythm (4–7 Hz, amplitude of 20–150 μV, commonly seen when drowsy), and
δ rhythm (0.5–3 Hz, amplitude of 20–200 μV, commonly seen during sleep).
30 When infrasonic waves resonate with the head,
dizziness, numbness in limbs, confusion, and abnormal behavior can be caused.
30 The experiments in
New Zealand rabbit have shown that exposure to 16 Hz/130 dB infrasonic waves for 20 min significantly increases δ rhythm, and exposure to 6 Hz/110 dB can convert α to θ rhythm, indicating that brain wave activity in animals can be significantly suppressed by infrasonic waves.
13 Organ-type infrasonic weapons usually have frequencies ranging from 4 to 18 Hz, which correspond to the inherent vibration frequencies of various organs in the human body. The frequency for the torso is 7–13 Hz, the heart is 5 Hz, the
chest cavity is 4–6 Hz, the
abdominal cavity is 6–9 Hz, the
abdominal wall is 10 Hz, the
pelvic cavity and the chest wall are 6 Hz and 60 Hz, respectively.
9,
12,
15,
34 When the frequency of infrasonic waves is close to the inherent frequency of human organs, resonance occurs, leading to symptoms such as tinnitus,
palpitations, muscle spasms, difficulty breathing, and even rupture of blood vessels and organ damage.
9,
15,
18 When the frequency of infrasonic waves is less than 2 Hz, the human body responds as a whole rather than at the organ level.
27,
28,
33
3.3. Injury threshold
The
injury extent of infrasonic waves to the human depends on their power, frequency, and duration of exposure.
25 When the power is the same, the frequency determines the type of damage, while the duration determines the injury degree, which is also closely related to the frequency and sound pressure.
9,
25 Due to the different structures and inherent frequencies of humans and animals, the same infrasonic parameters can have varying effects on different organisms.
9 A test involving 15 males aged 20 to 25 years showed that exposure to 10 Hz/136 dB infrasound for 15 min resulted in symptoms such as
headaches,
dry mouth, difficulty swallowing, sweaty palms, and extreme fatigue. The average low- and mid-frequency
hearing thresholds decreased by 10–15 dB, and some internal organs experienced noticeable vibrations. After the exposure stopped, most of the symptoms disappeared within 10–30 min, but the feeling of fatigue persisted.
9 Infrasound of 12.5–20.0 Hz/105.0–113.5 dB for 6 h caused restlessness, muscle tremors, spasms, and decreased muscle strength in 67.8% of the subjects.
13 Exposure to infrasound at 1–30 Hz/125 dB can cause ear pressure sensations and a decrease in task performance,
13 at 95–110 dB for 20 min can make people drowsy and reduce work efficiency,
34 16 Hz/95 dB for 30 min can increase
diastolic blood pressure and heart rate.
34 However, some infrasound is harmless to the human body. For example, 2–15 Hz/115 dB do not affect task performance,
13 7.5 Hz/130 dB for 50 min has negligible effects on the human body,
34 8 Hz/130 dB for 30 min has no
adverse effects on most people,
34 10–15 Hz/130–135 dB for 30 min cannot affect hearing or
vestibular function,
34 7 Hz/142 dB for 15 min does not cause
dizziness or orientation disorders.
34 Animal experiments have shown that infrasound at 172 dB can cause breathing difficulties and even
suffocation in dogs, while at 6–9 Hz/195 dB can cause immediate death in monkeys and baboons.
6,
11 Exposure to infrasound at 16 Hz/105 dB for 10 min can shorten the tolerance time of rats to sound waves, and infrasound at 10 Hz/160 dB can interrupt tracking behavior in adult macaques, but it has no effect on
hearing measurement,
otoacoustic emissions (OAE), and auditory
brainstem responses.
34 Infrasound at 15–20 Hz/140 dB has no effect on pigs and macaques.
34
It is usually believed that infrasound at 90 dB is generally not harmful,
9 and 120 dB is the threshold level for infrasound damage.
11 Even short-term exposure to infrasound at 140 dB is enough to cause harm to the human body,
9,
34 and at 150 dB for 2–3 min can cause irreversible damage and even death.
6,
9,
10,
11 The International Infrasound Professional Committee in Paris has set the allowable infrasound intensity of 2 Hz at 130 dB, 4 Hz at 128 dB, 8 Hz
at 125 dB, and 16 Hz at 120 dB.
6,
11 According to the changes in
red blood cell membrane permeability, adenosine-triphosphat, and
succinate dehydrogenase activity, the impact of infrasound frequency is determined to be in the order of 16 Hz>8 Hz>4 Hz>2 Hz.
9,
10
3.4. Biological effects
The harmful biological effects of infrasound on the human body include: (1) vestibular effects, such as dizziness and nausea;
27,
28,
34 (2) auditory effects, such as auditory pain, sensation of pressure in the middle ear, and annoyance;
37 (3) visceral effects, such as nausea, chest tightness, and hallucinations;
27,
28,
34 (4)
cardiovascular effects, such as increased heart rate (averagely increasing 11/min) and elevated diastolic blood pressure (averagely increasing 1.2±0.27 kPa), but returned to normal after half an hour;
9 (5) psychological effects, such as fear, sadness, depression, anxiety, lack of concentration,
aversion, indifference, and sorrow;
25 (6) chronic effects, such as
rectal cancer,
colon cancer,
pancreatic cancer, etc.
27,
28,
38
Infrasound also has certain benefits to the human body. For example, sonic massage of 4 Hz/170 dB can stabilize the
progression of myopia,
13 and sonic waves with frequencies ranging from 0.1 to 3 Hz can relieve pain.
10 During anesthesia, moderate infrasound has sedative effects on
central nervous system, and reduces adverse reactions caused by surgical stimuli.
13 Sonic waves at 8–12 Hz can improve concentration, enhance learning efficiency, and increase alertness.
13,
34 If at 8–12 Hz/72–79 dB, permeability of tumor cell membranes can be changed, and the killing effect on
glioblastoma cells can be enhanced with 5-fluorouracil together.
13 Otherwise, the proliferation activity of
mesenchymal stem cells in the bone marrow can be increased by infrasound which inhibits
apoptosis.
13 Also, the
survival rate of guinea pigs during
hypersensitivity reactions can be increased by exposure to 10 Hz/155–160 dB for 10 min,
10 and
cognitive impairment in rats with
vascular dementia can be improved by infrasound.
9
3.5. Injury diagnosis
Due to surprise attack (fast propagation) and crypticity (inaudible and invisible) of infrasonic weapon assault, combined with its long operating distance and strong penetration capabilities,
12,
18 it is difficult for people to realize they have been damaged by infrasound timely, until they experience symptoms such as dizziness, nausea, chest tightness, hallucinations, fear, sadness, depression, and anxiety, which are often referred to as “mysterious symptoms”.
38 Still, it is difficult to determine the attack source and to diagnose quickly,
38 unless symptoms occur simultaneously in batch soldiers during wartime or gathering crowds during peacetime, or a infrasound detection device (such as a infrasonic sensor) is available at the scene.
3.6. Injury prevention and treatment
It is quite difficult to protect against sonic weapons.
2 The best protection is to minimize the infrasonic intensity and to shorten the exposure duration.
11,
15 Alternatively, it can be used to reduce resonance by absorption, isolation, and reducing energy during infrasound propagation. Although many materials can protect against medium and high frequency noise, the materials for protecting against infrasound and low-frequency noise are lacking at present.
9 Due to the strong penetration capability of infrasound, the equipment made of ordinary materials cannot provide effective protection. It is reported that the anti-infrasound
earplugs developed by Chinese scientists can effectively reduce human injuries.
9 In addition, high-intensity music can mask infrasonic waves and provide some relief for certain symptoms,
10,
11 and low-intensity infrasonic waves can alleviate the damage caused by high-intensity sonic waves, which may be used to increase the tolerance of the human to infrasound damage by pre-stimulating effects in the future.
9
Infrasound can activate the body's oxidative system, generate a large number of
free radicals, and further exacerbate
lipid peroxidation reactions, thus damaging
biological membranes. Therefore, antioxidants, such as α-tocopherol,
vitamin C, 2.3-dimethyl-2-sulfopropionate sodium,
imidazole derivatives, etc., and free radical scavengers have therapeutic effects on infrasonic weapon damage.
9,
10,
11 Glutamate receptor antagonists can effectively reduce the number of damaged neurons affected by infrasonic waves.
11
4. Intense sound weapons
4.1. Types and applications of the weapon
Intense sound weapons, also known as noise weapons, belong to audible sound weapons and currently have various products, including land-based, vehicle-mounted, and ship-borne versions.
18,
22 The acoustic wave disperser installed on armored vehicles by the U.S. military can reach up its SPL to 145 dB.
23 Also, SPL produced by the explosion of sound and light bombs can exceed 140 dB,
23,
39 and detonation shells can emit a loud noise of 172 dB.
17,
20,
23The Long Range Acoustic Device (LRAD), developed by the US, is the most famous intense sound weapon, which has been equipped with the U.S. Army, Navy, Marine Corps, and the Japan Maritime Self-Defense Force.
19,
38 The LRAD emits a high-frequency (1–2.5 kHz
36 or 2–4 kHz
29) directional sound beam at an angle of 150° to 300°.
27,
28 Its SPL is 165 dB at 1 m,
12,
30 and 140 dB at 300 m.
29 It has a range of 8.9 km36 can provide voice warnings within 2 km
23 or 3 km39 and be used for strong sound dispersion within 650 m.
23 The permanent hearing loss can be caused within 15 m.
27,
28 LRAD has different models including 100X, 300X, 500X, 1000X (for police use),
28,
38 and 2000X (for military use).
18,
19,
27,
28 It has been reported that the US military used LRAD in the wars in Afghanistan and Iraq.
31,
39,
40Likewise, the directional strong sound dispensers in various models developed by China have been widely used in public security, armed police, and coast guard units.
19
The impulse noise is generated by guns, cannons, and explosives, while the steady-state noise is produced by wheeled and tracked vehicles, aircraft, ships, and aircraft carriers.
41Impulse noise causes greater injury to the human body than steady-state noise, and individuals have higher susceptibility to it compared to steady-state noise.
29,
33 Usually, the impulse noise of small arms ranges from 130 to 175 dB,
42 and suppressors can reduce the impulse noise to 15–25 dB.
41 For example, the noise of handguns is 168 dB (5.0 kPa), rifles is 171 dB (7.2 kPa), 105 mm cannons is 188.0 dB (50.3 kPa), and mortar cannons is 189.2 dB (58 kPa).
33 Due to reflections, the duration of indoor noise is longer than that of outdoor noise (5–10 ms outdoors; over 100 ms indoors) with longer propagating distance.
41 Among US military veterans, 21% suffer from hearing loss,
43 and the incidence of PTS among soldiers after shooting training is 13% (the US),
44 or 24% (Sweden).
45 Among 419 French soldiers, tinnitus accounted for 87.4% (
n=366), hearing loss for 35.1% (
n=147),
ear pain for 21.2% (
n=89), and
hearing threshold shifts averaged 15.4 dB, subsequently hearing loss for more than 20%.
46
4.2. Mechanism and characteristics of damage
The human ear is most sensitive to impulse noise in the frequency range of 2–4 kHz
31 or 2–5 kHz,
12,
23 therefore, sonic weapons often select this sensitive frequency range. Additionally, the higher the frequency, the greater the sound power.
12 The
auditory system damaged by sonic weapons can be temporary or permanent conductive, sensorineural, or
mixed hearing loss.
34,
47 It is pointed out that low-frequency noise is more terrifying than high-frequency noise.
29 Low-frequency noise at 90–120 dB for 1 min can cause irritability and restlessness in humans, 110–130 dB can cause intestinal pain and nausea, 140–150 dB can cause severe
tissue damage, and the injury caused by 170 dB is similar to blast injury.
31,
33 Mid-frequency noise can cause resonance in body cavities,
33 however, high- and ultrahigh-frequency noise can cause extreme increases in body temperature, leading to tissue burns and dehydration, both of which can also cause bubbles formation in the tissues.
33
4.3. Injury threshold
The extent of damage depends on the acoustic power, frequency, and operating distance of the weapons.
20 The SPL of a normal conversation is about 60 dB.
29 At 120 dB, discomfort can be felt in the human ear, and the risk of hearing loss is high. At 135–162 dB,
eardrum rupture, labyrinth
bleeding, and peeling of the
organum spirale from the
basilar membranemay occur.
23,
37 The human tolerance to a noise level of 140 dB should not exceed 1 s,
48 and exposure to pulse noise of 4–6 kHz/140–155 dB for 2 ms can cause TTS, while longer or repeated exposure can lead to PTS.
33 Monkey exposed to a noise level of 160 dB for 10 min can result in PTS, pathological T and QRS waves on electrocardiograms, and cause
ischemic heart disease and myocardial infarction
31 The National Institute for
Occupational Safety and Health in the U.S. recommends that exposure to 110 dB should not exceed 1.5 min, 120 dB not exceed 9 s, and 129 dB not exceed 1 s, and 130–140 dB should be less than 1 s.
39 The US Department of Defense regulates that the maximum permissible noise level for unprotected ears is 140 dB, and noise levels equal to or above 140 dB can cause acute
acoustic trauma(AAT).
31
4.4. Biological effects
The biological effects of intense sound weapons can be divided into the following types: (1) auditory effects, referring to the sonic damage to the sound conduction pathway and resulting
tympanic membrane rupture, ossicles fracture, injury of vestibular
sensory organsand inner ear hair cells, so that conductive, sensorineural, or
mixed hearing loss, and some symptoms such as dizziness and tinnitus can occur. Besides, TTS or PTS can result in, with the most obvious high-frequency hearing loss at 3, 4, and 8 kHz, but indistinctive low-frequency hearing loss at 0.25, 0.5, and 1 kHz; (2) non-auditory effects, referring that systems of sympathetic nervous, neuroendocrine, gastrointestinal, immune, and other human organ are stimulated by strong sound, and result in
headache, dizziness, nausea, vomiting, increased heart rate and blood pressure.
34,
47 Moreover, these can become risk factors for pulmonary injury, cardiovascular and
cerebrovascular diseases, neurocognitive changes, and
gastrointestinal diseases.
12,
21,
31 It is reported that non-auditory effects will exacerbate auditory effects.
31 So far, research on auditory effects in humans is far more systematic and intensive than that on non-auditory effects, and the effects of strong noise on the nervous and cardiovascular systems has not been sufficiently emphasized.
31
4.5. Injury diagnosis
Diagnosing methods of AAT include pure-tone audiometry (PTA),
OAE, and
auditory evoked potentials, but PTA is the gold standard for diagnosis.
49,
50 A study showed that among 71 Swiss soldiers examined by PTA, 41 experienced AAT due to automatic carbine shooting, with the highest sensitivity at 11–14 kHz by PTA and the highest sensitivity at 3–6 kHz by OAE.
50 PTA examination also showed that occurrence rates of hearing loss in the US and the United Kingdom military was 20%–30% and 28%, respectively,
50 while the occurrence rate of
sensorineural hearing loss in the Thai military was 64.35%.
51
4.6. Injury prevention and treatment
4.6.1. Equipment protection
Both earmuffs and
earplugs can attenuate noise above 500 Hz by about 15–45 dB, but earmuffs are not as effective as earplugs for protecting against noise below 250 Hz, while foam earplugs can attenuate low-frequency noise by 35 dB
33,
41,
52 and reduce the occurrence rate of AAT by about 15 times.
51 Earmuffs combined with earplugs can protect against impulsive noise above 160 dB, and earmuffs combined with earplugs and sound-absorbing helmets can attenuate impulsive noise of 800–7000 Hz by 30–50 dB.
51 Protective equipment made with sound-absorbing materials is more effective in protecting against high-frequency noise than low-frequency noise.
33,
41 When professional protective equipment is not available, cotton balls, tissues, or cartridge cases can be used for noise protection.
51
4.6.2. Surgical operations
Some symptoms, such as TTS, tinnitus, pain, dizziness, and other auditory effects can recover within minutes or months.
33 About 80%–90% of small perforations in the tympanic membrane will be self-healing, and hearing will be restored even with small perforations bilaterally, while perforations larger than 1/3 of the
eardrum should be repaired surgically.
33Fractures or displacements of the middle ear ossicles also require surgical repair.
33 Deaf patients should use hearing aids or receive
cochlear implants to stimulate sensory neurons to restore hearing and speech abilities, which is the only reliable method for treating permanent hearing loss.
33
4.6.3. Drugs
The main purpose of
drug treatment is to improve cochlear
microcirculation and correct
tissue hypoxia; the earlier the medication, the better treatment effect.
53 Steroids are effective for sensorineural hearing loss by activating Na, K-ATPase in cochlear neurons, thereby improving cell osmotic pressure and chemical gradients to restore
neural conduction.
49,
53Commonly used doses of
Prednisolone are 1 mg/kg (up to 60 mg/day) for 10 consecutive days, regardless of the
route of administration.
46 Prednisolone can be combined with
Piracetam (a
neuroprotective and antithrombotic drug) at a dose of 8 mg/L normal saline per day for 10 consecutive days, with satisfactory treatment effect.
53 Methylprednisolone can be taken orally at a dose of 64 mg/day for the first 3 days, 32 mg/day for the next 3 days, and 16 mg/day for the following 3 days.
54 Hyperbaric oxygen therapy has vasodilating effects and can be used in combination with steroids.
46,
49,
54 Other drugs such as
Vitamin A,
Vitamin B1,
Nicotinic acid,
Vitamin E,
Lazabemide,
Ketamine,
Betahistine, and
Ginkgo Biloba can also be used.
46,
49
N-acetyl-L-cysteine is an antioxidant that can be used as a preventive medication before acoustic trauma occurs, or taken orally within 1 h after acoustic trauma at a dose of 400 mg (not exceeding 4 h) and administered again after 24 h, with a total dose of 800 mg, which is effective in treating TTS but cannot improve PTS.
55 Naphthoquinone Nitroxide,
Analgin,
Rizatriptan,
Zolmitriptan,
Acetylsalicylic Acid, Nimesulide, Ibuprofen, and
Naproxen Sodium can treat noise-induced headache, but
Naphthoquinone Nitroxide is the most effective, which is a
sympathomimetic drug that enhances
norepinephrine release and activates the
opioid system for analgesia. It can be used in
nasal spray form at a dose of 0.14 mg 3 times a day.
38
5. Ultrasonic weapons
At present, there is little literature and incomplete data on ultrasonic weapons, which may be due to the technological difficulties of weapon development and the low level of weapon practicality.
18,
20 The hand-held ultrasonic weapon, powered by a 9 V battery lasting for approximately 20 h, can emit ultrasound waves ranging from 15 to 30 kHz, with a maximum SPL of 130 dB56 or 145 dB17 and an effective range of 6 m.
56 The ultrasonic bullet developed by the US can transmit highly directional ultrasonic waves that can attack enemies in confined spaces such as caves.
12,
21
The wavelength of ultrasound is shorter than that of infrasound (<2 cm, for medical diagnosis ranging from 10 μm to 350 μm). Ultrasound has stronger directional propagation compared with that of infrasound, which is easy losses and scattering when propagating in the air, resulting in poor penetration. However, absorptive attenuation of ultrasound is small when propagating in liquids or solids, thus allowing them to penetrate through rocks, bricks, metal, and concrete walls up to 15 m thick.
12,
17,
21 Ultrasonic waves will be reflected when encountering different material interfaces, where they can be absorbed and converted into thermal energy, so increasing the interface temperature, and becoming more significant with higher frequencies.
12,
21
The symptoms of ultrasonic weapon injuries are similar to those of infrasonic weapons.
17Ultrasound can enhance air pressure and cause physiological reactions such as visual blurring, itching of the nose and mouth,
ear pain, skin heating, nausea, vomiting, abdominal pain, and result in skin burns and increasing body temperature at 160 dB. In addition, ultrasonic waves can cause bone fractures through resonance with the
skeleton.
25,
29,
37
6. Conclusion
Although sonic weapons have a low potential for causing severe damage and fatality to humans, infrasonic weapons have characteristics such as surprise attack, invisibility, long-range action, and strong penetration, making it not only difficult to diagnose timely but also quite difficult to prevent and treat. While intense sound weapons are relatively easy to diagnose and have many prevention and control measures, research on non-auditory effects still needs to be further enhanced, especially during wartime and non-war operations, when the damage to the human body is more extensive; therefore, future research should focus on its prevention and treatment. The symptoms of ultrasonic weapon injuries are similar to those of infrasonic weapons, but there is a lack of previous research report; thus, strengthening research on ultrasonic weapons injury should be one of the key areas in the future study of acoustic weapons.
CRediT authorship contribution statement
Yue Li: Writing – review & editing, Writing – original draft.
Guangming Yang: Writing – review & editing.
Yongbo Zhao: Data curation.
Bingcang Li: Writing – review & editing, Writing – original draft, Supervision, Conceptualization.
Strong write up.. The horn source of the infrasound. Really misses the mark on the dB.. does not take into consideration that ambient infrasound amplifies infrasound. iy uses frequencies near its intended frequencies to amplify them.. Initially readings showed much more defined spikes at specific frequencies at dB more reflective of the dBs published here. Stacking infrasound frequencies near each other likely allows for the generation of effects usually only seen at higher dBs.
They are also still lost in the delusional doldrums of the puzzle of how they are able to focus hyper focus infrasound. The easiest way to start to escape is to answer why they would try.. they wouldn’t and they don’t.
Really strong bio residence and correlation to widely reported symptoms of “directed energy” victims and undeniably correlates strongly with vast majority of “Havana syndrome” victims or what ever name it’s been given as of late.
Really brings up the shortcomings of ultrasound transmitted through gas.. but surprisingly to me it seems to travel quite far in solid without losing its payload. should look at its ability to follow solid structures possibly like an “electrical wire” for ultrasound. Resonance of different structures to produce ultrasound ?
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