ANTINOISE

From Big Medical Encyclopedia

ANTINOISE (ustar. synonym antiphons) — individual protection equipment of an acoustic organ and the prevention of various frustration of an organism caused by excessive noise. Items use hl. obr. when technical means of noise control (see) do not provide decrease it to safe limits. Items absorb sounds of various frequency and intensity, weaken action of noise on a human body, interfere with development of exhaustion. Systematic and the correct use of P. can prevent decrease in hearing (see. Acoustic injury ) and other frustration of an organism caused by excessive noise. Items to destination and to design subdivide into three types: inserts, earphones and helmets.

Fig. 1. Types of antinoise inserts: 1 — from silicone rubber; 2 — from spongy polymer; 3 — individual, cast in a form of acoustical pass; 4 — from the rubber which is put on rigid cores.

Antinoise inserts enter into outside acoustical pass. Inserts happen repeated and disposable. Numerous options of caps in the form of caps of various design and a form from rubber, rubber and other plastic polymeric materials which in certain cases are put on rigid cores (fig. 1) belong to inserts of repeated use. Antinoise inserts of repeated use release several types and the sizes; their weight is not regulated and fluctuates in limits to 10 g.

Fig. 2. Antinoise inserts of «Earplug»: 1 — separate inserts; 2 — packaging on 50 pieces of inserts.

A variety of forms and the amount of outside acoustical passes creates difficulties at individual adjustment of antinoise inserts. An exception are inserts disposable — the organic high-disperse cotton wool impregnated with paraffin, wax or other cementitious matters and also inserts from the organic materials capable to change the form depending on temperature or pressure, e.g. «Earplugs» — the commercial name of domestic antinoise inserts disposable from the organic perkhlorvinilovy filtering noise-absorbing material (FPP-Sh) cut by the squares 40 X 40 mm laid on 50 pieces in a box (fig. 2).

Fig. 3. Antinoise earphones: 1 — cups; 2 — the condensing rollers; 3 — a bridle.

Antinoise earphones represent cups, in a form close to a hemisphere, from light metals or plastic, filled with fibrous or porous sound absorbers, withheld by means of a bridle. On a way of fastening on the head they are subdivided into the independent, having a rigid or soft bridle, and built in a headdress (helmets, helmets, kerchiefs) of a pla other protection device (a respirator, points, guards, etc.). For a convenient and dense prileganiye to parotid area they are supplied with the condensing rollers from the synthetic pellicles which are often filled with air or liquid substances with big internal friction (glycerin, a liquid paraffin and so forth). The condensing roller at the same time damps fluctuations of the case of the earphone that is essential at low-frequency sound vibrations (fig. 3).

Fig. 4. Antinoise helmet: 1 - - rigid helmet; 2 — - earphones; 3 — the condensing roller; 4 — a hose for a poddutiya of the roller air.

Antinoise helmets — the most bulky and expensive of individual protection equipment of an acoustic organ. They are used at high levels of noise, often applied in a combination with earphones or inserts. The condensing roller located on edge of a helmet provides a dense prileganiye it to the head. There are designs of helmets with poddutiy the roller air for reliable fitting of the head (fig. 4).

P.'s efficiency is characterized by extent of weakening of the noise getting into outside acoustical pass. There are several methods of its assessment based on a threshold audiometriya (see). Most often use methods of shift of an absolute threshold of hearing, a method of the masked threshold and a method of balance of loudness. These methods of a research correspond to actual data for this or that P. more precisely, than physical methods with use, e.g., of acoustic probes. P.'s efficiency is expressed in a difference of the threshold levels received for unprotected and the protected ears during the giving of true tones or strips of noise.

The choice of individual means of protection of an acoustic organ depends on the power of noise, their spectral structure, time of action during the shift. Protection against powerful noise is provided by helmets (more often rigid) with the built-in antinoise earphones, the circular condensing roller, skintight to the head. Easing at low and average frequencies shall be within 15 — 25 dB, on high — to 40 — 60 dB.

Requirements to P. at expressed low - or a high-frequency range of noise are various. If in the first case of P. shall have the large volume of cups and to be rather heavy, then in the second they can be the lungs with the cups of small volume well adjacent to parotid area condensing with rollers.

In the USSR the weight (weight) of P. and force of their pressing to parotid area are standardized. Depending on a design and protective properties P. also groups (table) are divided into types.

Items shall provide effective weakening of surrounding noise, to be hygienic, safe and convenient in use (at the rate on a 4-hour shift), shall meet the requirements of an industrial design; shall not emit the toxic or irritating skin substances, to contaminate an integument, to cause the painful and irritating feelings. The design of earphones and inserts of repeated use shall allow their processing. The item should be applied from the first day of stay in a noisy situation that promotes prevention of a hearing disorder and emergence of other adverse effects connected with impact of noise.




Bibliography: Suvorov G. A. and Shkarinov L. N. Influence on a human body and animal intensive and long noise influences, in book: What logich. fiziol, the person, Adaptation of the person to extreme conditions, under the editorship of O. G. Gazenko, page 240, M., 1979, bibliogr.

L. N. Shkarinov.

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