- Clinical Neurophysiology: Repetitive transcranial magnetic stimulation creates a loud clicking sound simultaneous with exposure to magnetic pulses. It has potential for “auditory cognitive neuroscience” (i.e., perception of speech, music, natural sounds, emotion, memory, attention and production of auditory events), along with treating tinnitis. See patent for “RF Hearing Effect“.
- Journal of the American Medical Association: Persistent cognitive, inner ear/balance, and eye movement dysfunction, as well as sleep impairment and headaches, were observed among US government personnel in Havana, Cuba, associated with reports of directional audible and/or sensory phenomena of unclear origin. These individuals appeared to have sustained injury to widespread brain networks without an associated history of head trauma.
- US Army Medical Intelligence and Information Agency: Soviet and Eastern European scientists believe that biological harm occurs at non-thermal power densities. If Western nations strictly enforce stringent, non-thermal exposure standards, unfavorable effects on industrial output and military functions may occur. Eurasian communist countries could give lip service to strict standards, allowing their military to gain the advantage in electronic warfare and antipersonnel applications.
- Aerospace Medicine: Deaf subjects with 50 decibel hearing loss could hear RF sounds approximating perception in normal subjects. When asked to localize the source of the RF sound, the apparent source was a short distance behind their head, regardless of where the RF field was located.
- Journal of Applied Physiology: Electromagnetic fields generate sounds in normal and deaf humans, several hundred feet from the antenna. Attempts were made to match sounds induced by electromagnetic and acoustic energy. The closest match occurred when the acoustic amplifier was driven by the RF transmitter’s modulator, down to 400 μw/cm2, 425 to 1,310 MHz.
- Journal of Microwave Power: Pulse bursts of microwave energy stimulate resonant-type acoustical response in models of the brain irradiated by radar transmitter (5.655 GHz, 200 kW peak, and 1.10 GHz, 4 kW peak).
- Magnetic Resonance in Medicine: Evaluation of auditory thresholds for RF pulses generated by MRI coils (2.4 to 170 MHz, 16 +/- 4 mJ). Resonance mode for the skull was 1.7 kHz, with 11 kHz for the brain.
- Perceptual and Motor Skills: Applied electromagnetic patterns, with energy levels which are potentially within the range of both geomagnetic activity and contemporary communication networks, might allow all normal human brains to be affected by subharmonic frequency ranges around 10 Hz, +/- 0.1 Hz.
- Perceptual and Motor Skills: Electromagnetic equivalents (1 µT) of the acoustic signature for spoken words, applied across the temporoparietal lobes, correlates among participants who selected the target word within a group of words. Study discusses neurocognitive detection of emotional components of words, when transformed to electromagnetic equivalents.
- IEEE Engineering in Medicine and Biology: A significant limitation of transcranial magnetic stimulation is that the magnetic pulse delivery is associated with a loud clicking sound as high as 140 dB resulting from electromagnetic forces. There are concerns about hearing loss, induction of tinnitus, as well as tolerability.
- Scandinavian Audiology: Profoundly hard-of-hearing and deaf patients who were candidates for cochlear implants were examined by non-invasive extracranial electromagnetic stimulation (EMS). Although EMS evoked auditory sensations in most patients, severe cochlear damage and permanent hearing loss occurred in lab animals.
- Journal of Microwave Power and Electromagnetic Energy: The microwave auditory effect is the only well-established specific effect in realistic microwave exposure situations. The threshold for the effect depends on the energy density per pulse and may be as low as 20 mJ/m2 for people with low hearing threshold.
- Bioelectromagnetics: The human auditory response to pulses of RF EMF (2.4 MHz to 10 GHz) is a well established phenomenon. The induced sounds are similar to a click, buzz, hiss, knock, or chirp. They’re typically heard in quiet environments by people with good acoustic hearing at frequencies above 5 kHz.
- Electroencephalography and Clinical Neurophysiology: The acoustic artifact produced by the extracranial magnetic field stimulation coils in some clinical instruments may pose risks of temporary and permanent hearing loss in patients and clinicians when held in close proximity to the unprotected ear. Initial studies suggest that the magnetic field alone did not cause permanent hearing impairment.
- Electroencephalography and Clinical Neurophysiology: Extracranial electromagnetic stimulation (EMS) of human head models had impulse noise levels associated with hearing loss. Ear protectors reduced sound pressures reaching model head ear canals by 15-22 dB, and are recommended for patients exposed to EMS.
- Physics in Medicine and Biology: Evaluates how the shape of microwave pulses affects the sound wave amplitudes generated in an irradiated spherical head model. Also evaluates thresholds for human hearing effects as pulse repetition frequency is varied.
- Health Physics: Microwave auditory effect is the most widely accepted biological effect of microwave radiation (in the 100’s of MHz to 10’s of GHz). Upon absorption by soft tissues in the head, a thermoelastic wave of acoustic pressure travels by bone conduction to the inner ear, activating the cochlear receptors, similar to normal hearing.
- Magnetic Resonance in Medicine: To avoid RF-evoked sound pressure levels in the head rising above the discomfort threshold at 110 dB, an upper limit of 30 kW applied peak pulse power is suggested for MRI head coils and 6 kW for surface coils.