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

Military Medicine, Feb 2007 by Jauchem, James R, Cook, Michael C

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." Annies 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.