Study type: Medical/biological study (experimental study)

Human perception of illumination with pulsed ultrahigh-frequency electromagnetic energy med./bio.

By: Frey AH, Messenger Jr R
Published in: Science 1973; 181 (97): 356-358
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Aim of study (acc. to author and editor)

To study the perception of "sound" induced by irradiation with pulse-modulated, ultrahigh-frequency electromagnetic energy and to answer the following questions: 1) Is perceived loudness a function of peak power, average power, or both? 2) What is the required energy density for the perceptual threshold? 3) Is there a minimal or optimal pulse width? Are there modulation characteristics that yield the perception of pitch?

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.245 GHz
Modulation type: pulsed
Exposure duration: intermittent, 5 s off/2 s on
Exposure 2: 1.245 GHz
Modulation type: pulsed
Exposure duration: intermittent 5 s off / 2 s on

Exposure 1

Main characteristics
Frequency 1.245 GHz
Type
Polarization
Exposure duration intermittent, 5 s off/2 s on
Additional info vertical polarisation
Modulation
Modulation type pulsed
Repetition frequency 50 Hz
Additional info

pulse widths of 70, 60, 50, 30, 20, 10 µs, and 40 µs (special case)
Exposure setup
Exposure source
Setup The subject sat on a wooden stool with his back to the antenna and his head fixed in space by placing his chin on an acrylic rest mounted on a wooden pole.
Additional info Each trial started with a brief dim light; after a variable period of up to 5 s, a reference RF sound was presented for 2 s, followed by a silent period of about 5 s, and finally the RF sound of variable loudness was presented for 2 s. Occasionally, no variable RF sound was presented at the expected time in order to test for false positives.
Parameters
Measurand Value Type Method Mass Remarks
power density 90 mW/cm² peak value measured - 70 µs
power density 105 mW/cm² peak value measured - 60 µs
power density 125 mW/cm² peak value measured - 50 µs
power density 210 mW/cm² peak value measured - 30 µs
power density 315 mW/cm² peak value measured - 20 µs
power density 630 mW/cm² peak value measured - 10 µs
power density 0.32 mW/cm² mean measured - kept constant for all pulse widths
Measurement and calculation details

Average power density measurements were taken with a half-wave dipole antenna located where the center of the subject's head was placed during the experiment. Peak power density was derived by dividing by the duty cycle.

Exposure 2

Main characteristics
Frequency 1.245 GHz
Type
Polarization
Exposure duration intermittent 5 s off / 2 s on
Additional info vertical polarisation
Modulation
Modulation type pulsed
Repetition frequency 50 Hz
Additional info

pulse widths of 10, 20, 30, 50, 60, and 70 µs
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 370 mW/cm² peak value measured - -
power density 0.19 mW/cm² mean measured - 10 µs
power density 0.37 mW/cm² mean measured - 20 µs
power density 0.55 mW/cm² mean measured - 30 µs
power density 0.93 mW/cm² mean measured - 50 µs
power density 1.11 mW/cm² mean measured - 60 µs
power density 1.29 mW/cm² mean measured - 70 µs
Additional parameter details

Average power density was varied by varying the pulse width, while peak power density was held constant at 370 mW/cm².

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The perceived loudness of the radiofrequency sound and within the limitation of the radiofrequency parameters investigated here, is a function of peak power rather than average power. Calculations from the data presented indicate that in this particular study, the peak power required for perception is somewhat less than 80 mW/cm². A band of optimal pulse widths seems to exist for the effect and there are also radiofrequency modulation parameters that cause subjects to report hearing "sounds" with definite pitch and timbre characteristics.

Study character:

Study funded by