High-Intensity Acoustics for Military Nonlethal Applications: A Lack of Useful Systems

James R. Jauchem^*, PhD, Michael C. Cook^*, PhD

^* U.S. Air Force Research Laboratory, Human Effectiveness Directorate, Directed Energy Bioeffects Division, Brooks City-Base, San Antonio, TX 78235-5147.

Author Notes

Military Medicine, Volume 172, Issue 2, February 2007, Pages 182–189,
https://doi.org/10.7205/MILMED.172.2.182

Published: 01 February 2007

ABSTRACT

There have been many previous claims of nonlethal acoustic weapon effects, mostly in the popular rather than the scientific literature. Anecdotal reports of extraordinary effects can make meaningful assessment and review of this area very difficult. Acoustics research has shown that the nonlethal weapon capabilities of audible sound generators have been grossly overstated. Although high-intensity infrasound significantly disrupted animal behavior in some experiments, the generation of such energy in a volume large enough to be of practical use is unlikely because of basic physical principles. On the basis of experimentation completed to date at a number of institutions, it seems unlikely that high-intensity acoustic energy in the audible, infrasonic, or low-frequency range can provide a device suitable for use as a nonlethal weapon.

Introduction

Acoustic energy includes sound in the audible frequency (20–20,000 Hz) and infrasound (<20 Hz) ranges. In popular press articles, there have been many previous claims of either the potential usefulness or the actual existence of acoustic weapons. To avoid conflicting and false expectations, it is essential that military commanders and policymakers understand the real capabilities and limitations of nonlethal technologies before putting them into the hands of troops. Narrow-band, high-intensity, acoustic energy in the audible frequency range and infrasound have been proposed for use as nonlethal weapons. Some potential nonlethal weapons proposed for law enforcement agencies may be adapted from military technology.¹ One of the most frequently cited technical needs, according to law enforcement officers and other individuals who coordinate agency responses to terrorist incidents, is “improved nonlethal weapons to apprehend terrorists.”²

The purposes of this article are to review anecdotal and laboratory reports of acoustic weapon effects and to assess the potential usefulness of high-intensity acoustic energy in nonlethal weapon applications, particularly in relation to psychological effects. Potential underwater applications are not discussed in this article.

In addition to journal articles, books, and book chapters (i.e., “publications” as strictly defined by Easterbrook et al.³), items from the so-called “gray literature”⁴ (such as abstracts, proceedings of meeting presentations, conference reports, technical reports, patents, and official government documents) were used for this review. Items were identified from the following electronic databases: National Library of Medicine PubMed (including Medline), Biosis, Embase, Toxicology Literature Online (Toxline Special), Developmental and Reproductive Toxicology/Environmental Teratology Information Center database, Agricola, Inspec, JICST-EPlus (Japanese Information Center for Science and Technology), Pascal (Institut de l'Information Scientifique et Technique, Centre National de la Recherche Scientifique), CAB Abstracts, Chemical Engineering and Biotech Abstracts, Life Sciences Collection, SciSearch, National Technical Information Service, Applied Science and Technology Abstracts, Academic Search Premier, Master File Premier, PsychInfo/Psychological Abstracts, Aerospace Database, and Online Computer Library Center FirstSearch (including General Science Index, Applied Science and Technology Index, Electronic Collections Online, and ArticleFirst). Accounts from newspaper articles were not included.

Previous Claims of Acoustic Weapon Effects

Audible Frequencies

A prototype “acoustic blaster” was described as “developed and tested successfully.”⁵ Another acoustic weapon prototype was alleged to produce effects “ranging from minor annoyance to total incapacitation.”⁶ Arkin⁷ suggested that acoustic weapons were so far advanced that deployment was imminent.

A complex waveform acoustic device was described as a prototype nonlethal weapon.^8,9 It was later portrayed as “a viable crowd deterrent.”¹⁰ Van Williams¹¹ listed several acoustic non-lethal weapons “in advanced test and evaluation stages.” A device that could cause “emission of an acoustical pulsed periodic stimulus” that “effectively suppresses determined human operations” was mentioned by Rynne.¹² Lewer and Schofield¹³ stated that acoustic weapons developed by Scientific Applications & Research Associates were at an advanced stage of production. Rappert and Wright¹⁴ noted that acoustic weapons “are thought to offer unprecedented options” in nonlethal applications.

The United Kingdom has implemented export controls for “acoustic devices represented by the manufacturers … as suitable for riot control purposes.”¹⁵ More recently, a device nicknamed the “acoustic bazooka,” more formally known as the directed stick radiator or high-intensity directed acoustics, was developed to serve as either a voice-hailing signal device¹⁶ or supposedly a nonlethal weapon that makes “people turn as green as grass” with sickness.¹⁷ The original research effort, however, consisted of equipment development and was not intended to evaluate aversive effects on humans.¹⁶ No results of any such testing have been published, to date, in the scientific literature. It has been suggested that the device could “have the capacity to knock people off their feet.”¹⁸ A “long-range acoustic device” has been deployed by the U.S. military in Iraq and by the New York Police Department.¹⁹ The device was intended for use as a communication device, however.²⁰ Although some news outlets have referred to recent uses of the long-range acoustic device (e.g., on a cruise ship on November 7, 2005²¹) as “nonlethal weapon” deployment, such systems are still described by the manufacturer as “designed beneath pain thresholds” and “not nonlethal weapons.”²² They have been represented elsewhere as devices “designed to modify the behavior of personnel with a high intensity warning tone”²³ and to “deliver a shrill 145 dB tone … causing headaches and panic.”²⁴

Ben-David²⁵ recently reported that the Israel Ministry of Defence developed an acoustic device (dubbed “the shout”) that is “capable of incapacitating crowds at a range of 100 m without causing permanent physical damage.” Sound intensity or frequencies were not disclosed, however. Such a system has been described as the “shophar,” “a nonlethal, high power acoustic radiator used for riot suppression.”²⁶

In contrast to the enthusiastic descriptions mentioned above, Moore and Freund²⁷ correctly suggested that any aversive audible device should be considered “as a tool” to study acoustic effects “and not a weapon.” Norbut²⁸ also appropriately noted that such acoustic devices were “still in the experimental phase of development.” Altmann^29,30 noted that many claims by Scientific Applications ' Research Associates or others regarding potential acoustic weapons were not accurate. Chaloner and Ryan³¹ considered acoustic weapons to be “unacceptable by currently existing international treaties.” If prototypes of such devices cannot be developed into effective weapons, however, evaluation and discussion of the acceptability may be unnecessary.

Infrasound

Infrasound is generally defined as sound below 20 Hz. Anecdotal reports of extraordinary acoustic or infrasound weapon effects can make meaningful assessment and review of this area very difficult. A scientific journal article by Gavreau³² is often cited in the popular literature as evidence of an accidental death attributable to infrasound. Such an event, however, was not reported in the article. Instead, the effects of infrasound were described as “certainly unpleasant.” Altmann³³ noted that present-day scientists at the same institute have doubts about Gavreau's conclusions, because his experiments have not been replicated.

In another report, an infrasound weapon device that produced one ultrasound frequency at 16,000 Hz and a second at 16,002 Hz, which would combine to form a “beat frequency” of 2 Hz, was described. Supposedly, “when the two frequencies mix in the human ear, they become intolerable,” with people becoming “giddy or nauseous” and, in extreme cases, fainting.³⁴ This “squawk box”³⁵ (reported to have been built and tested by the British Army) was portrayed as being highly directional, so that it could be focused on individuals in a riot. It was later admitted that this “weapon” was a hoax³⁶ and was simply “disco gear” mounted on two armored personnel carriers.³⁷ In addition, Rehn and Riggs,³⁸ after performing a literature search, could find no data to support the earlier claims of effects.

Observers invited to the Center for Testing of Devices with Non-Lethal Effects on Humans in Moscow³⁹ reported “a 10-Hz acoustic generator which would be used to deliver a pulse about the size of a baseball that could knock you down or more, depending on how you power it.” It was suggested that the handheld device could be “kicked up to lethal level.” Adams⁴⁰ and Roush⁴¹ mentioned efforts by the U.S. military and other militaries to build similar devices.

It has often been suggested that infrasound generators could be powerful enough to trigger nausea or diarrhea.⁴² Acoustic systems using infrasound could, in theory, cause a loss of muscle control or unconsciousness.⁴³ Exposure to 16 Hz has been presumed to “make people feel nauseated and disoriented.”⁴⁴ Remarkable properties have been attributed to infrasound, including the capacity to “debilitate people for hours and even days,” with “pulsing in their internal organs and blurred vision, both of which can lead to …, in rare cases, death.”⁴⁵ Thomas⁴⁶ reported a claim in a Chinese military medical journal⁴⁷ that an infrasound weapon had already been developed and tested and that the device was adjustable, to cause controllable amounts of disorientation, nausea, vomiting, and incontinence. However, the details of that work were not reported in the English literature. Bortz⁴⁸ mentioned potential use by the Marine Corps of “low frequency sound waves that can knock a person out but cause no permanent damage.” Armies are alleged to have already deployed “devices generating infrasound.”⁴⁹ Synetics Corp.⁵⁰ referred to one specific type of infrasound generator and noted, “with sufficient energy, the resulting infrasonic waves can be disabling or lethal.” A statement that “low frequency infrasound systems were considered for use in Somalia”⁵¹ could give readers the false impression that such weapons actually exist and are viable options for commanders to use. Military scenarios have even included the mock employment of infrasonic weapons.⁵²

Simple “nuisances” caused by infrasound (without “weaponization potential”) were mentioned by Cabal and Roszak.⁵³ Kuralesin⁵⁴ postulated that “infrasound exposure is associated with a hypothalamic crisis with sensory/somatovegetative symptoms.” One system, known as the “infrapulse-generator,” was assumed to have “strong biologic impact on wellness by generating resonances in entire organs of the human body.”⁵⁵ The resonances were “suspected to cause increasing of pulsebeat frequency and in certain circumstances sudden nausea.” No details on hypotheses for such effects were provided.

Possible Mechanisms Mediating Effects of Acoustic Nonlethal Weapon Applications

Audible Frequencies

Potential effects of high-intensity acoustic energy in the audible frequency ranges can be divided into three categories, (1) aural effects (effects on hearing, including temporary or permanent threshold shifts), (2) extra-aural effects mediated through hearing and subsequent activation of the sympathetic nervous system (e.g., increases in heart rate and blood pressure), and (3) non-hearing-related extra-aural effects (e.g., pain, vertigo, nausea, and vomiting). This review does not address aural effects in any detail. Permanent damage to hearing would probably not be acceptable in terms of policy considerations relating to the use of nonlethal weapons.

Because of the acoustical “mismatch” between air and the surface of a solid body, only a small percentage of incident acoustical energy at higher audible frequencies is absorbed. Below 1000 Hz, however, there is appreciable absorption of airborne sound by the body. In very intense sound fields, widespread stimulation of somatic mechanicoreceptors can occur.⁵⁶ At very low frequencies (below 100 Hz), the body responds as a whole, and oscillations of the limbs, head, and chest may occur. Moore et al.⁵⁷ suggested that effects of exposure to acoustic energy could be expected to range from “disorientation to even lethality.” Noppen et al.⁵⁸ speculated that exposure to music from commercial loud speakers (ranging down to 30 Hz) could have caused four cases of spontaneous pneumothorax.

Effects of impulsive sound (e.g., from “blast waves”) in animals and humans were reviewed extensively by Altmann³³ and are not discussed further in this article, with the exception of one device that was tested at the Air Force Research Laboratory. Another item, the vortex ring generator,⁵⁹ is not strictly an acoustic device but rather is designed to integrate modalities of concussion, flash, chemicals such as malodors and tear gas, and marker dyes into a single delivery system. Diversionary devices such as “flash-bang grenades”⁶⁰ are also not exclusively acoustic devices. Therefore, additional details are not provided in this review.

Infrasound and Low-Frequency Sound

Although by common definition low-frequency sound is in the audible range, in this article the nonlethal weapon potential of low-frequency sound and infrasound are jointly considered. On the basis of animal experimentation, it is known that the attenuation of low-frequency sound in some body organs is much less than that of high-frequency sound.⁶¹ Therefore, infrasound and low-frequency sound may be more likely to be absorbed and to have some effect on body function.

Some investigators have suggested that infrasound can directly affect the vestibular system, thereby inducing vertigo and, potentially, motion sickness (see articles by Harris et al.⁶² and Von Gierke and Parker⁶³ for reviews). The mechanism of these effects could be a change in the activity of the labyrinth and/or otolith organs.

The idea that low-frequency vibrations may be used to make people feel ill may be traced back to the observation that some people feel queasy during earthquakes. Tesla reportedly duplicated the effect with a “vibrating chair.”⁶⁴ However, those observations were based on mechanical vibration in solids. The possible responses to vibration include the degradation of performance and the production of discomfort.⁶⁵ Although it has been suggested that there are parallels between the effects of low-frequency sound/infrasound and vibration,^66,67 mechanical vibration couples to the body much more efficiently than do airborne sound waves. Therefore, intense levels of low-frequency noise would be necessary to achieve the same level of discomfort resulting from low-frequency vibration applied to the body via mechanical contact.⁶⁸

“Body resonance” could be important in correlating the mechanical amplification of vibration in various parts of the body with physiological responses; that is, different parts of the body are in resonance at varying frequencies.⁶⁹ For example, Von Gierke and Parker⁷⁰ reported that human thoracoabdominal viscera exhibit resonance at 4 to 6 Hz. Kjellberg and Wikström⁷¹ reported that stomach motility in humans is affected by whole-body vibration (at 3 Hz and 6 Hz), as measured by electrogastrography. Changes in physiological function may be directly attributable to the differential vibratory movement or deformation of particular body structures. Because sound couples to the body less efficiently than does mechanical vibration (as noted above), the possible effect of infrasound on body organs with different resonant frequencies is less clear. It has been hypothesized that body resonances, such as the abdomen at 10 Hz and the chest wall at 60 Hz, could be stimulated by high-intensity infrasound.⁷² Unlike other investigators who suggested detrimental effects of infrasound, Arabadzhi⁷³ hypothesized that infrasound of moderate intensity at frequencies of 8 to 13 Hz could promote maintenance of a human's state of alertness. This has not been verified.

Previous Studies of Acoustic Effects

Audible Frequencies

Effects of high-intensity audible sound on the vestibular system have been demonstrated in animal experiments. For example, at frequencies of 500 Hz and 2000 Hz, stimulation of the vestibular system of guinea pigs was demonstrated at sound pressure levels of ≥142 dB.⁷⁴ In studies of human subjects, noise from jet engines (at levels of ∼140 dB) produced disturbances in equilibrium.⁷⁵

At sound pressure levels as low as 120 dB, resonances in the nasal cavities or sinuses appear to be related to a heightened sense of touch in that area of the body.⁷⁶ Allen et al.⁷⁷ reported a tickling sensation in persons in the vicinity of a 165-dB sound source. Becker et al.⁷⁸ found that perceived workload was elevated in personnel exposed to intermittent jet engine noise (maximum of 95 dB).

Experiments were performed at the Air Force Research Laboratory to determine whether narrow-band, high-intensity, acoustic energy in the audible frequency range could be used as a nonlethal weapon.⁷⁹ Four acoustic devices were tested, (1) a compressed air-driven siren (Scientific Applications & Research Associates, Inc., Cypress, California), (2) a combustion-driven siren (the dismounted battle space battlefield laboratory) (Scientific Applications & Research Associates, Inc.), (3) an impulsive acoustic device (the sequential arc discharge acoustic generator) (U.S. Army Research Laboratory, Adelphi, Maryland), and (4) a complex waveform generator (the Gayl Blaster, U.S. Army Armament Research, Development & Engineering Center, Picatinny, New Jersey). The compressed air-driven siren produces a high degree of airflow to create sound. Although exposure to the device significantly affected the performance of some rhesus monkeys, the effect was probably attributable to the substantial airflow, which unavoidably passed directly over the animals. The effects of the dismounted battle space battlefield laboratory siren on goal-directed behavior (panel pressing for food) of goats were both minimal and transient. Exposure to the sequential arc discharge acoustic generator⁸⁰ affected operant behavior of swine but failed to significantly affect performance in rhesus monkeys. The Gayl Blaster had no effects on behavior (panel pressing) in goats. In summary, none of the four devices tested would have obvious utility as a nonlethal weapon.

Audible sound can result in short-term reactions of a “startle response” nature (e.g., increased heart rate, muscle tension, and constriction of skin blood vessels). Studies of these effects were reviewed by Jansen⁸¹ and are not addressed in detail here. In general, levels of >90 dB may be aversive to mammals and cause startle responses.⁸²

It is important to note that the effects of audible sound cannot always be differentiated from those of infrasound.⁸³ Infrasound may be audible to humans at sufficient intensity, but it is also easily masked by sound at higher frequencies.⁸⁴

Infrasound and Low-Frequency Sound

There have been a number of reviews on the effects of infrasound and low-frequency sound on humans, including changes in performance.^{62,63,66,85,86} Studies generally involved exposures of short duration, at frequencies above the infrasound frequency range, at <154 dB. Some studies produced results suggesting effects on performance, whereas others indicated a lack of effects. A review by Pawlaczyk-Luszczyńska⁸⁷ reflects the lack of studies of infrasound at high intensities in more-recent years.

Most studies of infrasound and low-frequency sound effects on the human body have involved occupational aspects of chronic exposures.^67,88,–90 Studies of potential acute effects of infrasound were discussed previously.⁹¹ Effects discussed included slight dizziness, nausea, and feelings of apprehension⁹²; coughing, choking, and a generalized stress reaction⁹³; eardrum⁹⁴ and skin⁹⁵ vibration sensations; and annoyance and fatigue.⁹⁶ Slarve and Johnson⁹⁷ found that humans reported a small amount of chest or abdominal vibrations during exposure to frequencies between 4 and 25 Hz, with a threshold at 8 Hz of 132 dB.

Borredon⁹⁸ noted that 7.5-Hz infrasound at 130 dB for 50 minutes had a negligible effect on simple reaction time in men. Borredon and Nathie⁹⁹ exposed men to pure tones of infrasound (again at 130 dB) and found that some subjects exhibited decreased performance on some tasks, whereas other subjects actually exhibited improvements in performance. Kyriakides and Leventhall¹⁰⁰ reported no statistically significant effects on task performance in subjects exposed to a band of infrasound extending from 2 Hz to 15 Hz at 115 dB. The authors speculated that performance on tasks of longer durations could potentially be affected by infrasound; however, there has been no additional evidence to support this claim. Moller¹⁰¹ found that the most conspicuous effects in men and women exposed to frequencies of 1 to 30 Hz (maximal sound pressure, 125 dB) were a feeling of annoyance and a sensation of ear pressure. A decrement in performance was noted during a cue utilization task; however, there were no effects on eight other tasks (including tests of logic, short-term memory, and reaction time). Nussbaum and Reinis¹⁰² reported that most individuals tolerated exposure to 8 Hz at 130 dB for 30 minutes with no ill effects. In other studies, humans exposed to 10 to 15 Hz at 130 to 135 dB for 30 minutes exhibited no changes in hearing level, vestibular function, or autonomic nervous functions.¹⁰³ Faustov et al.¹⁰⁴ noted a decrease in work capacity after 20 minutes of exposure to infrasound.

Landström et al.¹⁰⁵ reported that exposure to infrasound at 95 and 110 dB caused drowsiness in human subjects. Ising et al.¹⁰⁶ exposed 100 volunteers to infrasound and found no equilibrium disturbances or nausea but stated that “infrasound acted as a stressor and probably causes fatigue and a reduction in respiratory rate.” Danielsson and Landström¹⁰⁷ noted increased diastolic blood pressure in men exposed for 30 minutes to 16-Hz infrasound at a level of 95 dB. Nonspecific responses of humans to infrasound (e.g., a temporary increase in heart rate) have been reported.¹⁰⁸ In a study by Okamoto et al.,¹⁰⁹ body sway was observed to be more prominent in humans exposed to infrasound of 15 Hz, compared with 10 Hz, but no changes in respiration, blood pressure, pulse rate, and several other measures were found.

Alker¹¹⁰ described a study performed by Wyle Laboratories in 1993, using human volunteers. The purpose of the study was to investigate the feasibility of denying access to a bunker through the use of high-intensity sound. An electromechanical sliding valve modulated the release of compressed air into a room 5.18 m long, 4.27 m wide, and 3.05 m high. The most effective frequencies were above the infrasound range (63 Hz and 100 Hz). Alker¹¹⁰ hypothesized that, although more-useful body resonances (in terms of an access-denial effect) would occur at infrasound frequencies, only relatively low-intensity sound could be achieved in the infrasound range.

Alves-Pereira¹¹¹ reviewed possible extra-aural pathological conditions attributable to high-amplitude (>90 dB), low-frequency (defined by him as 0–500 Hz, thus including both infrasound and some audible frequencies) sound. The author dealt mainly with the concept of noise-induced vibration and noted that, although detrimental extra-aural effects have been suspected, inconsistencies between studies did not allow definitive conclusions. On the basis of experimental data, Huang et al.¹¹² suggested that infrasonic fields may adversely affect minesweeper crews' psychological health, but implications for non-lethal weapon effects are unknown.

Investigations with rodents have supplemented the human studies. For example, Yamamura and Kishi,¹¹³ using a test to measure equilibrium, found that endurance time of rats was reduced by exposure to 16 Hz at 105 dB after 10 minutes. Additional studies of rodents are not covered in this review.

In one series of experiments,¹¹⁴ tracking behavior of five adult male rhesus monkeys (Macaca mulatta) was substantially disrupted by exposure to 10-Hz infrasound at 160 dB. There was no evidence of any postexposure alterations in tympanometry, distortion product otoacoustic emissions, or auditory brainstem evoked potentials.

In another series,¹¹⁵ three micropigs (Sus scrofa) were exposed to acoustic energy (40 and 80 Hz at 164 and 167 dB, respectively) generated in a progressive wave tube by two Mark VI acoustic generators (Team Corp., Burlington, Washington). Large changes in air pressure were necessary to obtain high sound levels (with obviously high volumes of air flowing directly across the animals). No gross physiological effects were evident after 1 to 2 minutes of exposure. Immediately after release from the test chamber, the subjects showed normal ambulation (i.e., no vertigo) and readily consumed both food and water. There was no evidence of incapacitation induced by the acoustic energy per se.

Exposure to infrasound of 10 to 20 Hz, in a reverberant resonant chamber,⁹⁵ had minimal impact on consummatory and escape behavior. Rhesus monkeys performing a continuous, compensatory-tracking task were also not substantially affected.

Assessment of the Practicality of Using Acoustic Weapons

Infrasound and other acoustic generators represent a completely new mode of weapons based on novel physical principles (compared with existing nonlethal weapons). This novel approach may be part of the attraction for some. In this case, however, a lack of understanding of the physical principles could lead to the premature development of “prototype weapons” before testing or even reasonable consideration of such principles has occurred. Studies mentioned above (e.g., Ref. 79) have shown that the weapon capabilities of audible sound generators have been grossly overstated.

Vogel¹¹⁶ reviewed potential psychological effects of high-intensity acoustic energy. He suggested that sound pressure levels necessary to create annoyance (i.e., 115 dB) could be produced out to ranges of 1000 feet but such effects would be of negligible use as a nonlethal weapon.

One may consider useful indoor applications to be more likely, because energy can be concentrated more easily. On the basis of the previous work by Von Békésy¹¹⁷ and Von Gierke and Parker,⁶³ who reported a pain threshold in humans at a level of 140 dB at frequencies of 15 and 20 Hz, respectively, some of the exposures in our indoor experiments (including those with a sound pressure of 145 dB at 20 Hz) might have been expected to cause noticeable effects. Such effects, however, were not seen in experiments with either pigs or monkeys exposed to this high sound level.⁹⁵ This lack of effect is consistent with some of the earlier work by Mueller and Mayes,¹¹⁸ in which squirrel monkeys exposed to 2 Hz at 140 dB showed no evidence of discomfort. Some of those exposures lasted for 6 hours.

A prototype acoustic test chamber, developed to support experiments at infrasonic frequencies,^119,120 can produce sound pressures in excess of 140 dB. The test volume, however, is only 5 m³. Stagg¹²¹ developed a portable device capable of producing >150 dB of infrasound (into a test volume of 30 cm³). Although some experiments used technology that enabled achievement of sound pressures as high as 165 dB (at 0.5 Hz), those studies were performed using a small steel chamber. The use of infrasound in such small volumes would not appear to be relevant to hostage rescue scenarios.

Harris and Johnson¹²² exposed humans to 7 Hz at 142 dB for 15 minutes and found no decrements in performance and no subjective reports of dizziness or disorientation. The authors concluded that potential adverse effects of infrasound had been exaggerated in previous reports. Johnson¹²³ stated, “… infrasound is an overrated phenomenon as far as some authors would have you believe. Animals and people do not ‘fall apart’ due to infrasound. The ‘infrasonic death ray’ should at best be confined to the comics.”

In a review of the technology, the Swedish Defence Material Administration concluded that the possible danger attributable to infrasound “has been much over rated.”¹²⁴ According to Backteman et al.,¹²⁵ the Swedish Board of Occupational Safety and Health stated that there was no scientific proof of an association between infrasound and consequences such as nausea and malaise. Moller¹⁰¹ also suggested that extra-auditory effects of infrasound “seem to have been exaggerated.” Bunker126 noted that the alleged effects of infrasound for use as a nonlethal weapon have been questioned because of contradictory evidence presented in previous reports. Small¹²⁷ speculated that forthcoming technological innovations could result in an effective acoustic weapon that would not be subject to problems of direction and attenuation. When discussing the practical limitations of technology, however, Altmann¹²⁸ suggested that, because of basic physical principles, the development of a useful weapon using high-intensity acoustic energy is unlikely. Regarding infrasound, Altmann³³ noted that “it turns out that infrasound or prominent in journalistic articles or does not have the alleged drastic effects on humans.” In another assessment of nonlethal acoustic technology, no useful extra-aural behavioral effects were reported.¹²⁹ “Infrasound auditory devices” were included in examples of programs that were discontinued after negative assessments.¹³⁰

Even if an effect could be obtained in a volume large enough to be of use in a hostage rescue scenario, a notable limitation of infrasound acoustics for use as a nonlethal weapon is the requirement for large amplifiers and large-volume speakers.¹³¹ This may severely limit the mobility of any proposed weapon. Swanson132 noted that, even though a small percentage of society may be hypersensitive to infrasound, that aspect does not constitute a basis for development of a nonlethal acoustic weapon. As Heal¹³³ pointed out, “even the most effective device will have little value if it cannot be easily and quickly employed.”

The lack of practicality of using acoustic weapons has not prevented several patents relating to such technology from being issued.^134–136 Some research on potential acoustic nonlethal weapon prototypes has continued despite the lack of a repeatable useful bioeffect.¹³⁷ Murphy¹³⁸ pointed out that, without sufficient attention to bioeffects regarding nonlethal weapon concepts (including acoustic energy), military services could end up developing expensive hardware that would be operationally useless.

Conclusion

On the basis of results of numerous investigators, it seems unlikely that high-intensity acoustic energy in the audible, infrasonic, or low-frequency ranges will provide a device suitable to be used as a nonlethal weapon.

Acknowledgments

All animal research at the Air Force Research Laboratory mentioned in this review was performed in accordance with approved protocols under the Federal Animal Welfare Act (PL 89-544), Department of Defense Directive 3216, and Air Force Regulation 169-2.

References

1. Fischetti M: Less-than-lethal weapons. Technol Rev 1995; 98: 14-5.

2. Stambaugh H. Tillery C, Schaenman P: Inventory of State and Local Law Enforcement Technology Needs to Combat Terrorism. National Institute of Justice Research in Brief 173384. Washington. DC. U.S. Department of Justice, 1999.

3. Easterbrook PJ, Berlin JA, Gopalan R, Matthews DR: Publication bias in clinical research. Lancet 1991: 337: 867-72.

4. Alberani V, De Castro Pietrangell P, Mazza AM: The use of grey literature in health sciences: a preliminary survey. Bull Med Library Assoc 1990; 78: 358-63.

5. Sze H, Gilman C, Lyon J, Naff T, Pomeroy S. Shaw R: Non-lethal weapons: an acoustic blaster demonstration program. Presented at National Defense Industrial Association Non-Lethal Defense III; February 25-26, 1998; Laurel, MD.

6. U.S. Army Research Office: High powered acoustic weapon. In: Advanced Concepts and Technology II. Alexandria, VA, U.S. Army Research Office, 1995.

7. Arkin WM: Acoustic anti-personnel weapons: an Inhumane future? Med Confl Surviv 1997: 14: 314-26.

8. Anonymous: NSAP funds student thesis research. Nav Postgrad School Res 1998; 8: 26.

9. Gayl F: High intensity sound as a nonlethal weapon. Mar Corps Gaz 1998; 82: 29-30.

10. Anonymous: Survivability and force protection. Army Mater Command Sci Technol News 2000; 5: 1-3.

11. Van Williams T: Filling an Operational Requirement: The Nonlethal Approach. Newport, RI, Naval War College. 1998.

12. Rynne T: Non-Lethal Devices: Federal Research in Progress: Small Business Innovation Research 1996. Washington, DC, U.S. Department of Commerce, 1996.

13. Lewer N, Schofield S: Non-Lethal Weapons: A Fatal Attraction? London. United Kingdom, Zed Books, 1997.

14. Rappert B, Wright S: A flexible response? Assessing non-lethal weapons. Technol Anal Strateg Manage 2000; 12: 477-92.

15. Ministry of Defence: Strategic Export Controls: Annual Report. London, United Kingdom, Foreign and Commonwealth Office, Department of Trade and Industry, 1999.

16. American Technology Corp.: Acoustic Bazooka Proof-of-Concept: Final Report. Project K02TH082H00. San Diego. CA. American Technology Corp., 2002.

17. Kenyon HS: Cutting-edge sonic equipment offers many military applications. Signal 2002; 56: 43-6.

18. Lewer N: Non-lethal weapons: operational and policy developments. Lancet 2003; 362: 20-1.

19. Davison N, Lewer N: Bradford Non-Lethal Weapons Research Project Research Report 6. Bradford, United Kingdom, Centre for Conflict Resolution, University of Bradford, 2004.

20. McQuery C: The Testimony of the Honorable Charles McQuery, Under-Secretary, Directorate of Science and Technology, U.S. Department of Homeland Security, to the U.S. Senate Committee on Commerce, Science, and Transportation: Hearing on Enhancing Border Security. Washington, DC, U.S. Senate Committee on Commerce, Science, and Transportation, 2004.

21. American Technology Corp.: Long range acoustic device. Defense Update, 2005. Available at http://www.defense-update.com/products/1/LRAD.htm; accessed October 22, 2005.

22. Pappalardo J: Acoustic systems enter homeland security market. Natl Def 2005; 90: 10.

23. Grimes J: Modeling Sound as a Non-Lethal Weapon in the COMBATXXI Simulation Model. Naval Postgraduate School. Master's Thesis, Monterrey, CA, 2005.

24. Vinokur R: Acoustic noise as a non-lethal weapon source. Sound Vibrat 2004; 38: 19-24.

25. Ben-David A: New non-lethal weapon shouts a warning to rioters. Jane Def Wkly 2004; 41: 14.

26. State of Israel, Ministry of Industry, Trade, and Labor: EORD has developed and produced the "SHOPHAR." Available at http://www.tamas.gov.il/CmsTamat/ ICAProfiles.aspx?id=48%20&Ptype=0; accessed December 20, 2005.

27. Moore HL Jr, Freund CT: Aversive audible acoustic devices. In: Proceedings of the National Defense Industrial Association's Joint Services Small Arms Symposium, Exhibition, and Firing Demonstration. Crane, IN, Naval Surface Warfare Center, 2000. Available at http://www.dtic.mil/ndia/nld4/moore.pdf.

28. Norbut GW: Non-Lethal Weapons: Force Enabler for the Operational Commander Conducting Peace Operations. Newport, RI, Naval War College, 2001.

29. Altmann J: Acoustic weapons: myths and reality. In: Jane's Non-Lethal Weapons Conference: Fielding NLW for the New Millennium. London, United Kingdom, Jane's Publishing, 1999.

30. Altmann J: Non-lethal weapons: the case for Independent scientific analysis. Med Confl Surviv 2001; 17: 234-47.

31. Chaloner E, Ryan J: Weapons and the law [letter[. Lancet 1999; 353: 2078.

32. Gavreau V: Infrasound. Sci J 1968; 4: 33-7.

33. Altmann J: Acoustic weapons: a prospective assessment. Sci Glob Secur 2001; 9: 165-234.

34. Anonymous: Army tests new riot weapon. New Sci 1973; 59: 684.

35. Rodwell R: "Squawk box" technology. New Sci 1973; 59: 667-8.

36. Young R: Exotic audio research. Wire 1997; 157: 1-9. Available at http:// www.thewire.co.uk/archive/interviews/exotic_audio_research.html; accessed December 21, 2005.

37. Home S: There's no success like failure. Variant 1996; 2: 18-9.

38. Rehn KW, Riggs PK: Non-Lethal Swimmer Neutralization Study. Technical document 3138. Austin, TX, Applied Research Laboratories. University of Texas, 2002.

39. Anonymous: Russians continue work on sophisticated acoustic weaponry. Def Electron 1994; 26: 12.

40. Adams J: The Next World War: Computers Are the Weapons and the Front Une Is Everywhere. New York, NY, Simon & Schuster, 1998.

41. Roush W: The soldier as geek. Technol Rev 1998; 101: 95.

42. Morgan J: Bang! You're alive. Sci Am 1994; 270: 22-4.

43. Alexander LR, Klare JL: Nonlethal weapons: new tools for peace. Issues Sci Technol 1995; 12: 67.

44. North Atlantic Treaty Organization: Non-Lethal Weapons. Brussels, Belgium, North Atlantic Treaty Organization, North Atlantic Assembly, International secretariat, 1997.

45. Kocher R: Rumbly in the tumbly. Bull At Sci 2003; 59: 9-10.

46. Thomas TL: Human network attacks. Milit Rev 1999; 79: 23-33.

47. Anonymous: New concept weapons and its medical-related problems (in Chinese]. Beijing Renmin Junyi 1997; 9: 507-8.

48. Bortz J: New Weapons Provide Alternative for Marines Dealing with Non-combatants. Washington, DC. U.S. Marine Corps, 1998.

49. Coupland RM: "Non-lethal" weapons: precipitating a new arms race [editorial]. BMJ 1997; 315: 72.

50. Synetics Corp.: Army SBIR award: parametric difference waves for low frequency acoustic propagation. 1997. Available at http://hometown.aol.com/ultra21753/ weapon.htm; accessed October 17, 2001.

51. Richardson D: Non-lethal options. Def secur Rev 1998; 2: 44-7.

52. Bunker RJ: National security implications of emerging forms of warfare. Presented at the University of New Hampshire Non-Lethal Technology Innovation Center's First Annual Non-Lethal Technology and Academic Research Symposium; May 3-5. 1999; Quantico, VA.

53. Cabal C, Roszak E: Nuisances caused by infra-sounds [in French]. Arch Mal Prof 1974: 35: 848-9.

54. Kuralesin NA: Health related and medico-biological aspects of the effects of infrasound [in Russian]. Noise Vibrat Bull 1997; 5: 221-6.

55. Detailing L, Backhaus J, Liehmann W. Thiel K-D: Infrapulse generator: an effective non-lethal weapon. In: Non-Lethal Weapons: New Options Facing the Future, pp 25-1-6. Karlsruhe, Germany, DWS Werbeagentur und Verlag, 2001.

56. Stephens RWB, Bate AE: Acoustics and Vibrational Physics. London, United Kingdom, Edward Arnold Publishers, 1966.

57. Moore HL Jr, Shippell RJ Jr, Koeppel BJ, Freund CT, O'Malley K: Acoustic characterization of Bunker 1201. Presented at the National Defense Industrial Association's 5th Annual Security Technology Symposium and Exhibition, Group II: Security-Related Research and Methodology; June 14-17, 1999; Norfolk, VA.

58. Noppen M. Verbanck S. Harvey J. et al: Music: a new cause of primary spontaneous pneumothorax. Thorax 2004; 59: 722-4.

59. Lucey G, Jasper L: Vortex Ring Generator. Laurel, MD, National Defense Industrial Association. 1998.

60. Lewis B: NIJ's less-than-lethal flash-bang round project. Correct Today 2003; 65: 117-9.

61. Peters AJM. Abrams RM, Gerhardt KJ, Longmate JA: Three dimensional sound and vibration frequency responses of the sheep uterus. J Low Freq Noise Vibrat 1991; 10: 100-11.

62. Harris CS, Sommer HC, Johnson DL: Review of the effects of infrasound on man. Aviat Space Environ Med 1976; 47: 430-4.

63. Von Gierke HE, Parker DE: Infrasound. In: Handbook of Sensory Physiology, Vol. V: Auditory System, Part 3: Clinical and Special Topics, pp 355-624. Edited by Keidel WD, Neff WD. Berlin, Germany, Springer-Verlag, 1976.

64. Hecht J: Not a sound idea: nonlethal acoustic weapons seem to be doomed. New Sci 1999; 161: 17.

65. Guignard JC: Vibration. In: A Textbook of Aviation Physiology, Section VI: Noise and Vibration, pp 813-94. Edited by Gillies JA. Oxford, United Kingdom, Pergamon Press, 1965.

66. Broner N: The effects of low frequency noise on people: a review. J Sound Vibrat 1978; 58: 483-500.

67. Landstrom U: Occupational aspects of infrasound and whole body vibrations. Arh Hig Rada Toksikol 1983; 34: 287-93.

68. Kryter KD: Physiological. Psychological, and Social Effects of Noise. Report NASA-RP-1115. Hampton, VA, National Aeronautics and Space Administration Langley Research Center, 1984.

69. Dupuis H: Biodynamic behavior of the trunk and the abdomen during wholebody vibration. Acta Anaesthesiol Scand 1989; 90(Suppl): 34-8.

70. Von Gierke HE, Parker DE: Differences in otolith and abdominal viscera graviceptor dynamics: implications for motion sickness and perceived body position. Aviat Space Environ Med 1994; 65: 747-51.

71. Kjellberg A, Wikstrom BO: Acute effects of whole-body vibration: stabilography and electrogastrophy. Scand J Work Environ Health 1987; 13: 243-6.

72. Anonymous: Infrasound [editorial]. Lancet 1973; 2: 1368-9.

73. Arabadzhi VI: Infrasound and biorhythms of the human brain. Biophysics 1992; 37: 130-1.

74. Reschke MF: High-Intensity, Audio-Frequency Vestibular Stimulation in the Guinea Pig. Miami University, Doctoral Dissertation, Oxford, OH, 1971.

75. Dickson EDD. Chadwick DL: Observations on disturbances of equilibrium and other symptoms Induced by jet engine noise. J Laryngol Otol 1951; 65:154-65.

76. Davis H, Parrack HO, Eldredge DH: Hazards of Intense sound and ultrasound. Ann Otol Rhinol Laryngol 1949; 58: 732-8.

77. Allen CH, Frtngs H, Rudnick I: Some biological effects of Intense high frequency airborne sound. J Acoust Soc Am 1948; 20: 62-5.

78. Becker AB. Warm JS, Dember WN, Hancock PA: Effects of Jet engine noise and performance feedback on perceived workload in a monitoring task. Int J Aviat Psychol 1995; 5: 49-62.

79. Sherry CJ, Cook MC, Brown GC, Jauchem JR, Merritt JH. Murphy MR: An Assessment of Four Acoustic Devices on Animal Behavior. Technical report AFRL-HE-BR-TR-2000-0153. Brooks AIr Force Base, TX, Air Force Research Laboratory, 2000.

80. Boesch H, Benwell B, Ellis V: A High-Power Electrically Driven Impulsive Acoustic Source for Target Effects Experiments and Area-Denial Applications. Adelphi, MD, Army Research Laboratory, 2000.

81. Jansen G: Physiological effects of noise. In: Handbook of Acoustical Measurements and Noise Control, Ed 3, pp 25-1-19. Edited by Harris CM. New York, NY, McGraw Hill, 1991.

82. Manci KM, Gladwin DN, Villella R, Cavendish MG: Effects of Aircraft Noise and Sonic Booms on Domestic Animals and Wildlife: A Literature Synthesis. Report NERC-88/29. Fort Collins, CO, U.S. Fish and Wildlife Service National Ecology Research Center, 1988.

83. Pimonow L: Physical and physiological action of Infra and low-frequency sound. Rev Acoust 1971; 15: 205-12.

84. Johnson DL: Infrasound: Its Sources and Effects on Man. Technical Report ARML-TR-76-17. Wright-Patterson Air Force Base, OH, Aeromedical Research Laboratory, 1976.

85. Von Gierke HE: Non-auditory effects of ultrasonic, infrasonic, and vibratory energy on man. In: Proceedings of the Conference on Acoustics and Societal Problems, pp 91-4. Harriman, NY. Acoustical Society of America, 1972.

86. Westln JB: Infrasound: a short review of effects on man. Aviat Space Environ Med 1975; 46: 1135-40.

87. Pawlaczyk-Luszczynska M: Infrasound in the occupational and general environment: a three-element microphone measuring method for locating distant sources of infrasound. Int J Occup Environ Health 1996: 1: 17-27.

88. Izmerov NF, Suvorov GA, Kuralesin NA, Ovakimov VG: Infrasound: the body's effects and hygienic regulation [in Russian]. Vestn Ross Akad Med Nauk 1997; (7): 39-46.

89. Branco NA, Alves-Pereira M: Vibroacoustic disease. Noise Health 2004; 6:3-20.

90. Feldmann J, Pitten FA: Effects of low frequency noise on man: a case study. Noise Health 2004; 7: 23-8.

91. Cook MC, Sherry CJ, Brown GC, Jauchem JR: Lack of Effects on Goal-Directed Behavior of High-Intensity Infrasound in a Resonant Reverberant Chamber. Technical report AFRL-HE-BR-TR-2001-0154. Brooks Air Force Base, TX, Air Force Research Laboratory, 2001.

92. Wever EC, Bray CW: The perception of low tones and the resonance volley theory. J Psychol 1936; 3: 101.

93. Mohr GC, Cole JN, Guild E, Von Gierke HE: Effects of low frequency and infrasonic noise on man. Aerosp Med 1965; 36: 817-24.

94. Nixon CW: Human Auditory Response to Intense Infrasound. Technical report AMRL-TR-74-2. Wright-Patterson Air Force Base, OH, Aeromedical Research Laboratory, 1974.

95. Cole JN, Mohr GC, Guild E, Von Gierke HE: The Effects of Low Frequency Noise on Man as Related to the Apollo Space Program. Technical report AMRL-TR-66-119. Wright-Patterson Air Force Base, OH, Aeromedical Research Laboratory, 1966.

96. Edge PM Jr, Mayes WH: Description of Langley Low-Frequency Noise Facility and Study of Human Response to Noise Frequencies below 50 cps. NASA technical note NASA-TN-D-3204. Hampton, VA, National Aeronautics and Space Administration Langley Research Center, 1966.

97. Slarve RM, Johnson DL: Human whole-body exposure to infrasound. Aviat Space Environ Med 1975; 46: 428-31.

98. Borredon P: Physiological Reaction of Human Subjects Exposed to Infrasound. Report 3710. Paris. France. Centre de Recherches de Medicine Aeronautique. 1972.

99. Borredon P, Nathie J: The psychological effects observed on a man exposed to an Infrasonic level of 130 dB. Paris, France, International Colloquium on Infrasound, 1973.

100. Kyriakides K, Leventhall HG: Some effects of infrasound on task performance. J Sound Vibrat 1977; 50: 369-88.

101. Moller H: Physiological and psychological effects of infrasound on humans. J Low Freq Noise Vibrat 1984; 3: 1-17.

102. Nussbaum DS, Reinis S: Some Individual Differences in Human Response to Infrasound. Report 282. Toronto, Canada, University of Toronto Institute for Aerospace Studies, 1985.

103. Taenaka K: A study on the effect of infrasound [in Japanese]. Nippon Jibiinkoka Gakkai Kaiho 1989; 92: 1399-415.

104. Faustov A, Fraiman B, Bosova L: The phase features of man and animal reaction to infrasound effect. In: Proceedings of the 6th International Congress on Noise as a Public Health Problem, pp 265-8. Nice. France, Institut National de Recherche sur les Transports et leur Securite. 1993.

105. Landstrom U, Danielsson A, Lindmark A, Lindqwlst M, Uszka L, Soderberg L: Exposure to Three Different Levels of lnfrasound, 95, 100 and 125 dB: Effects on Man [in Swedish]. Solna, Sweden, Arbetarskyddsstyrelsen, Publikationsservice, 1982.

106. Ising H, Market B, Shenoda F: Effects of Infrasound on Man [in German]. Federal Republic of Germany, VDI-Verlag, 1985.

107. Danielsson A, Landstrom U: Blood pressure changes in man during infrasonic exposure: an experimental study. Acta Med Scand 1985; 217: 531-5.

108. Martinik K, Opltova L: Human nonspecific response to sound stimulation. J Hyg Epidemiol Microbiol Immunol 1986; 30: 139-44.

109. Okamoto K, Yoshida A, Inoue J, Takyu H: The Influence of infrasound upon human body [in Japanese]. J UOEH 1986: 8(Suppl): 135-49.

110. Alker G: Acoustic Weapons: A Feasibility Study. Report DRA/SS(PS)/CR96039/ 1.0. Famborough, United Kingdom, Defence Evaluation and Research Agency, 1996.

111. Alves-Pereira M: Noise-Induced extra-aural pathology: a review and commentary. Avlat Space Environ Med 1999; 70(Suppl 3): A7-21.

112. Huang ZQ, Uang ZF, Shi XF, Yu H: The psychological effect of minesweeplng infrasonic field [in Chinese]. Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi 2003; 21: 27-9.

113. Yamamura K, Kishi R: Effects of infrasound on the Rota-rod treadmill performance of rats. Eur J Appl Physiol 1980: 45: 81-6.

114. Sherry CJ, Cook MC, Jauchem JR. Brown GC, Edris RW: The effects of infrasound on rhesus monkey performance of a continuous compensatory tracking task. Low Frequency Noise. Vibration and Active Control (in press).

115. Murphy MR Jauchem JR, Merritt JH, Sherry CJ, Cook MC, Brown GC: Acoustic bioeffects research for non-lethal applications. In: Non-Lethal Weapons: New Options Facing the Future, pp 9-1-13. Karlsruhe, Germany, DWS Werbeagentur und Verlag, 2001.

116. Vogel HH: The Applicability of Acoustic Energy as a Battlefield Weapon. Report for contract DA-18-001 -AMC-551PO. Aberdeen Proving Ground, MD, U.S. Army Limited War Laboratory, 1964.

117. Von Bekesy G: On the hearing threshold and limit of perception of slow, sinusoidal changes in air pressure. Ann Phys 1936; 26: 554-66.

118. Mueller AW, Mayes WH: Acoustic Exposure Tests of Squirrel Monkeys in the Langley Low Frequency Noise Facility. NASA Langley Working Paper 412. Hampton, VA, National Aeronautics and Space Administration, Langley Research Center, 1967.

119. Boesch HE, Benwell BT, Reiff CG: Design and Test of a Prototype Acoustic High-Intensity Infrasonic Test Chamber. Army Research Laboratory Technical Report ARL-TR-2137. Adelphi. MD, Army Research Laboratory, 2000.

120. Boesch HE, Reiff CG, Benwell BT: A prototype infrasonic test chamber (HILF1). Presented at National Defense Industrial Association Non-Lethal Defense IV; March 20-22, 2000; Vienna, VA.

121. Stagg J: A compact infrasound and pressure waveform generator for use with small cavities. J Med EngTechnol 1980; 4: 186-9.

122. Harris CS. Johnson DL: Effects of Infrasound on cognitive performance. Aviat Space Environ Med 1978; 49: 582-6.

123. Johnson DL: Auditory and Physiological Effects of Infrasound. Technical report ARML-TR-75-33. Wright-Patterson Air Force Base, OH, Aeromedical Research Laboratory, 1975.

124. Defence Material Administration: Infrasound: A Summary of Interesting Articles. Report FMV:ELEKTRO-A12:142/83. Stockholm, Sweden, Defence Material Administration. Radio Department, 1985.

125. Backteman O, Kohler J, Sjoberg L: Infrasound: tutorial and review: part 2. J Low Freq Noise Vibrat 1983; 2: 176-210.

126. Bunker RJ: Non-lethal weapons conferences. Milit Rev 2000; 80: 103-4.

127. Small SC: Small arms and asymmetric threats. Milit Rev 2000; 80: 33-41.

128. Altmann J: Acoustic Weapons: A Prospective Assessment: Sources, Propagation and Effects of Strong Sound. Ithaca, NY, Cornell University Peace Studies Program, 1999.

129. National Research Council: An Assessment of Non-Lethal Weapons Science and Technology. Washington, DC, National Academies Press, 2003.

130. Anonymous: Researchers fill gaps for less-than-lethal weapons. Natl Def 2005; 89: 50-1.

131. Siniscalchi J: Non-Lethal Technologies: Implications for Military Strategy. Occasional paper 3. Maxwell Air Force Base. AL, Center for Strategy and Technology, Air War College. Air University, 1998.

132. Swanson DC: Non-lethal acoustic weapons: facts, fiction, and the future. Presented at the University of New Hampshire Non-Lethal Technology Innovation Center's First Annual Non-Lethal Technology and Academic Research Symposium; May 3-5, 1999; Quantico, VA.

133. Heal CS: What will the 'magic bullet" look like? In: Non-Lethal Weapons: New Options Facing the Future, pp 15-1-8. Karlsruhe, Germany. DWS Werbeagentur und Verlag, 2001.

134. Drewes W: Sonic weapon system. U.S. patent 4.349,898. September 14, 1982.

135. Loos HG: Subliminal acoustic manipulation of nervous systems. U.S. patent 6.017,302, January 25, 2000.

136. Naff JT, Shea JH: Acoustic cannon. U.S. patent 5,973.999, October 26. 1999.

137. Tiron R: Acoustic-energy research hits sour note. Natl Def 2002: 86: 29, 41.

138. Murphy MR: Biological effects of non-lethal weapons: Issues and solutions. Presented at National Defense Industrial Association Non-Lethal Defense III; February 25-26, 1998; Laurel, MD.

Author notes

The views and opinions expressed in this article are the authors' own and do not necessarily state or reflect those of the U.S. government.

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