Utdrag ur Microwaves and Behavior (American Psychologist 3/1975)
American Psychologist(APA) is the official peer-reviewed academic journal of the American Psychological Association. Page 396
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Microwaves and Behavior (American Psychologist 3/1975)
+Oddly enough, the mass of the interposed material does not seem to be too critical; I successively used smaller and smaller pieces of material as sonic transducers until it was necessary to impale tiny pieces on a toothpick, yet the clicking sounds induced in the material by microwave pulses were clearly audible to me.
+Sharp and Grove (Note 2) found that appropriate modulation of microwave energy can result in direct “wireless” and “receiverless” communication of speech.
+The capability of communicating directly with a human being by receiverless radio” has obvious potentialities both within and without the clinic.
Microwaves and Behavior (American Psychologist 3/1975)
Microwaves and Behavior by Don Justesen, American Psychologist, March 1975, pp. 391-401.
To “hear” microivave energy, it must first be modulated so that it impinges upon the “listener” as a pulse or a series of pulses of high amplitude. At first spurned by most microwave investigators in the United States, the radio- frequency hearing, or Frey effect, was repeatedly dismissed as an artifact until behavioral sensitivity to low densities of microwave energy was demonstrated in rats in an exquisitely controlled study by Nancy King (see King, Justesen, & Clarke, 1971). Shortly after the completion of the study and its informal dissemination via the invisible college, the skeptics began to appear in appropriately equipped microwave laboratories in the United States with requests to “listen to the microwaves.” A majority was able to “hear” the pulsed microwave energy, thereby belatedly confirming the claims made by Frey for nearly a decade.2
Recent work reported by Foster and Finch (1974) suggests that the Frey effect may be a thermohydraulic phenomenon. The authors suspended a microphone in a container of water that was radiated by pulsed microwaves at low-averaged densities of energy. The microphone delivered signals to an amplifier, the audio output of which was not unlike that “heard” by directly radiated human subjects. Since water changes density as its temperature is altered, the minuscule thermalizations produced in it upon absorption of the pulsed microwaves were sufficient to initiate small but detectable changes of hydraulic pressure.
Sonic transduction of pulsed microwaves at low-averaged densities has been demonstrated by Sharp, Grove, and Gandhi (1974) in materials lacking in
2There is irony here worthy of parenthetical comment. Consider that subspecies of human being, the experimental psychologist, who distrusts introspective data so thoroughly that a proposition based on them is considered highly suspect until corroborating data are observed in lower animals. The irony in the present case is that the demonstration of behavioral sensitivity to microwaves by a dumb animal does not imply that the animal is having an auditory “experience.” I was dubious about the Frey effect until I saw rats react to low densities of pulsed radiation; this conversion occurred despite my being one of the sizable minority that cannot hear microwaves under direct radiation. The other side of the coin of paradox is exemplified by a colleague, a confirmed cynic, who, while being irradiated in my presence, said, “Well, I can hear the <censored> microwaves, but I still don’t believe it!”
water, for example, in carbon-impregnated plastic and in crumpled sheets of aluminum foil. Even subjects who cannot hear microwaves when directly radiated by them can readily perceive clicking sounds when a piece of energy- absorbing material is interposed between the head and a radiator of pulsed microwave energy. Oddly enough, the mass of the interposed material does not seem to be too critical; I successively used smaller and smaller pieces of material as sonic transducers until it was necessary to impale tiny pieces on a toothpick, yet the clicking sounds induced in the material by microwave pulses were clearly audible to me.
The demonstration of sonic transduction bated and unresolved question of microwave energy by materials lacking in water lessens the likelihood that a thermoacoustic transduction probably underlies perception. If so, it is clear that simple heating as such is not a sufficient basis for the Frey effect; the requirement for pulsing of radiations appears to implicate a thermodynamic principle. Frey and Messenger (1973) demonstrated and Guy, Chou, Lin, and Christensen (1970) confirmed that a microwave pulse with a slow rise time is ineffective in producing an auditory response; only if the rise time is short, resulting in effect in a square wave with respect to the leading edge of the envelope of radiated radio-frequency energy, does the auditory response occur. Thus, the rate of change (the first derivative) of the wave form of the pulse is critical factor in perception. Given a thermodynamic interpretation, it would follow that information can be encoded in the energy and “communicated” to the “listener.” Communication has in fact been demonstrated. A. Guy (Note 1), skilled telegrapher, arranged for his father, a retired railroad telegrapher, to operate a key, each closure and opening of which resulted in radiation of a pulse of microwave energy. By directing the radiations at his own head, complex messages via the Continental Morse Code were readily received by Guy. Sharp and Grove (Note 2) found that appropriate modulation of microwave energy can result in direct “wireless” and “receiverless” communication of speech. They recorded by voice on tape each of the single- syllable words for digits between 1 and 10. The electrical sine-wave analogs of each word were then processed so that each time a sine wave crossed zero reference in the negative direction, a brief pulse of microwave energy was triggered.
By radiating themselves with these “voice modulated” microwaves, Sharp and Grove were readily able to hear, identify, and distinguish among the 9 words. The sounds heard were not unlike those emitted by persons with artificial larynxes. Communication of more complex words and of sentences was not attempted because the averaged densities of energy required to transmit longer messages would approach the current 10 mW/cm2 limit of safe exposure. The capability of communicating directly with a human being by receiverless radio” has obvious potentialities both within and without the clinic. But the hotly debated and unresolved question of how much microwave radiation a human being can safely be exposed to will probably forestall applications within the near future.
The U.S. limit of 10 mW/cm2 is actually an order of magnitude below the density that many investigators believe to be near the threshold for thermal hazards (Schwan, 1970). There are two camps of investigators in the United States, however, who believe that the limit is not sufficiently stringent. In the first camp of conservatives are those who accept the Soviet’s belief that there are hazardous effects unrelated to heating from chronic exposures to fields of low density (< 1 mW/cm2); some agree with Milton Zaret (1974), a New York ophthalmologist, who holds that severely debilitating subcapsular lesions of the eyes may develop years, even decades, after exposure to weak microwave fields. Others tend to reject the notion that weak microwave fields produce this anomalous cataract, because of lack of substantiating, evidence from the clinic or the laboratory (Appleton & Hirsch, 1975). But these conservatives are possessed of a vague unease simply because of the Soviet’s limit of continuous permissible exposure is three orders of magnitude below that of the United States.3
Utdrag 2
The demonstration of sonic transduction bated and unresolved question of microwave energy by materials lacking in water lessens the likelihood that a thermoacoustic transduction probably underlies perception. If so, it is clear that simple heating as such is not a sufficient basis for the Frey effect; the requirement for pulsing of radiations appears to implicate a thermodynamic principle. Frey and Messenger (1973) demonstrated and Guy, Chou, Lin, and Christensen (1970) confirmed that a microwave pulse with a slow rise time is ineffective in producing an auditory response; only if the rise time is short, resulting in effect in a square wave with respect to the leading edge of the envelope of radiated radio-frequency energy, does the auditory response occur. Thus, the rate of change (the first derivative) of the wave form of the pulse is critical factor in perception. Given a thermodynamic interpretation, it would follow that information can be encoded in the energy and “communicated” to the “listener.” Communication has in fact been demonstrated. A. Guy (Note 1), skilled telegrapher, arranged for his father, a retired railroad telegrapher, to operate a key, each closure and opening of which resulted in radiation of a pulse of microwave energy. By directing the radiations at his own head, complex messages via the Continental Morse Code were readily received by Guy. Sharp and Grove (Note 2) found that appropriate modulation of microwave energy can result in direct “wireless” and “receiverless” communication of speech. They recorded by voice on tape each of the single- syllable words for digits between 1 and 10. The electrical sine-wave analogs of each word were then processed so that each time a sine wave crossed zero reference in the negative direction, a brief pulse of microwave energy was triggered.
By radiating themselves with these “voice modulated” microwaves, Sharp and Grove were readily able to hear, identify, and distinguish among the 9 words. The sounds heard were not unlike those emitted by persons with artificial larynxes. Communication of more complex words and of sentences was not attempted because the averaged densities of energy required to transmit longer messages would approach the current 10 mW/cm2 limit of safe exposure. The capability of communicating directly with a human being by receiverless radio” has obvious potentialities both within and without the clinic. But the hotly debated and unresolved question of how much microwave radiation a human being can safely be exposed to will probably forestall applications within the near future.
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