THE EFFECTS OF ULTRASONIC VIBRATIONS ON MAN.
PSYCHOLOGICAL CORP NEW YORK
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Contradictory reports are cited about biological and psychological effects of exposure to jet engines, to defices used to produce ultrasonic vibrations experimentally, and of participation in high speed flight. The effects upon man are alleged to involve nausea, disturbance of equilibrium, fatigue, mental confusion, headache, and auditory, visual, and motor disturbances. The effects are said to be transient. Disturbances of equilibration, fatigue, and confusion are the most frequently reported symptoms. These deleterious effects are attributed to ultrasonic vibrations. The logic by which ultrasonic vibrations become the cause is unclear in many of the reports. Effects of ultrasonic energy when applied locally to man are considered. In general, heat develops at the site of application and appropriate sensory stimulation results. Spectral analyses of the noise obtained near turbo-jet engines on the ground or aircraft in flight show that both sonic and ultrasonic vibrations are produced. Under the conditions studied, sonic components exceed the ultrasonic components in intensity. Intensity levels appear to be reduced as engine speed decreases. There is evidence that, with increasing air speed, the overall intensity level of the noise increases and strong energy components may appear at ultrasonic frequencies as well as in the audible range. According to one study, this tendency is exaggerated as the speed approaches a Mach number of 1.0. If it is established that exposure to vibrations from current type engines or aircraft is harmful, such effects would appear to be more closely related to the high intensities involved rather than the high frequencies arising from these sources. Author
- Stress Physiology
- Environmental Health and Safety