The specificity of measurements at low sound frequencies in aeroacoustics

Studies of "noise pollution the" of territories which are placed near the railroads or street railway, and also experimental studies of sound fields of local noise zones (race circuit, airports, gunnery range) which were carried out in recent years by the acoustics department employees confirm need of rationing both levels of sound pressure, and oscillatory velocity of medium particles for control of noisiness level at low sound frequencies. Methods of calibration in close field of pressure gradient receivers at the anechoic chamber and real room are discussed.