Development of technology and vehicles, improvement of technological processes and the equipment are followed by increase in power and dimensions of cars that causes a tendency of increase of low-frequency components in ranges and emergence of an infrasound which is rather new, not completely studied factor of the production environment.
The infrasound can be the cause of resonant fluctuation of the ship masts leading to their breakage (the plane can lead impact of an infrasound on design elements to similar consequences. Low-frequency sound vibrations can be the cause of emergence over the ocean quickly arising and also quickly disappearing dense ("as milk") fog ─ atmospheric moisture, the discharges condensed during a phase, can not manage to be dissolved in air during the subsequent phase of compression, but in too time is capable to disappear "instantly", during some periods of lack of infrasonic fluctuations. And, at last, the infrasound with a frequency of 5 — 7 hertz can get to a resonance with a pendulum of the mechanical, wrist watch having the same period of fluctuations.
In practice usually use electromechanical generators of ultrasound which action is based on ability of some materials to change the sizes under the influence of magnetic (magnetostriction generators) or electric field (piezoelectric generators) to receiving ultrasound, thus generators make sounds of high frequency.