[Occurrence and evaluation of a law frequency noise in residential buildings]

Low-frequency noise emitted into the environment by technical equipment in the residential buildings, including equipment of workshops for services or production near these buildings, was measured. In the spectrum of noise derived from installations and equipment in residential buildings and shops low frequency (20-125 Hz) sounds and infrasounds (below 20 Hz) were detected. Their sources were mainly pumps in hydrophors, lifts, cooling machinery, central heating, air conditioning and ventilating installations. The analysed noise was in a small degree only damped by partitions in buildings and penetrated more easily than higher-frequency noise, without exceeding usually the permitted levels. Noises with dominating low-frequency sounds are regarded by the inhabitants as troublesome and causing various adverse psychosomatic effects, such as pulsation feeling, somnolence, headaches, nausea etc. The present system of noise assessment leaves low-frequency noise aside and fails to protect sufficiently the inhabitants against this nuisance.