The Forensic expert kollegium conducts all types of acoustic measurements.
Infrasound refers to elastic waves similar to sound waves but having a frequency below the threshold perceptible by the human ear.
In nature, infrasound waves occur during earthquakes, storms, hurricanes, and tsunamis. Technogenic sources of infrasound include high-power technological equipment: metal-cutting and woodworking machines, press equipment, power-generating equipment, boiler houses, elevator equipment, commercial equipment and refrigeration units, air intake shafts and ventilation equipment, as well as transport systems (especially near overpasses, suspension bridges, and tunnels).
Human organs have their own natural resonant frequencies. When exposed to sound at these frequencies, they may undergo internal structural changes, potentially leading to a loss of normal functioning. If the frequency of the affecting sound coincides with brain rhythms, disturbances in cerebral activity may occur. Being in different parts of a room where infrasound waves propagate may cause varying reactions of human organs and body systems. In such premises, a zone of infrasound wave gradient may be identified, where work efficiency decreases, the ability to distinguish sound impulses and light flickers is reduced, and a hypercoagulation reaction of the blood develops due to the effect of infrasound on blood vessel walls.
The standardized parameters of constant infrasound are sound pressure levels in octave frequency bands with geometric mean frequencies of 2, 4, 8, and 16 Hz. The standardized parameters of non-constant infrasound are energy-equivalent sound pressure levels in octave frequency bands with geometric mean frequencies of 2, 4, 8, and 16 Hz, as well as the equivalent overall sound pressure level.
According to the hygienic standard «Indicators of safety and harmlessness of infrasound exposure on humans», approved by Resolution № 37 of the Council of Ministers of the Republic of Belarus dated January 25, 2021, the maximum permissible levels of infrasound at workplaces, permissible levels in residential and public premises, and in residential development areas are as follows:
| Measurement location | Sound pressure levels, dB, | Overall sound pressure level, dB Lin | |||
|---|---|---|---|---|---|
| in octave bands with geometric mean frequencies, Hz | |||||
| 2 | 4 | 8 | 16 | ||
| Work of varying degrees of physical intensity | 100 | 95 | 90 | 85 | 100 |
| Work of varying degrees of intellectual and emotional intensity | 95 | 90 | 85 | 80 | 95 |
| Residential development area | 90 | 85 | 80 | 75 | 90 |
| Residential and public building premises | 75 | 70 | 65 | 60 | 75 |
The Forensic expert kollegium performs infrasound level measurements at industrial workplaces, in residential development areas, and within residential and public buildings.
You may contact the Forensic expert kollegium for consultation regarding infrasound level measurements at: Minsk, Zhukovskaga St., 11A, 4th floor
or by phone: +375 (17) 317 04 71; +375 (17) 317 04 72; +375 (17) 317 04 73; +375 (17) 317 04 74; +375 (17) 317 04 76; +375 (29) 109 60 11; +375 (44) 588 60 11.
©K.Dadzkou