SU1231160A1 - Wedge-type sound absorber - Google Patents

Abstract

A SLEEP sound absorber, comprising a frame filled with sound absorbing material and covered with acoustically transparent material, characterized in that, in order to expand the active sound absorption region towards low frequencies, the sound absorbing and acoustically transparent materials are separated by cavities limited by the frame members. (L SO

Description

one

The invention relates to building acoustics and can be used in the construction of silenced sound cameras designed for precise acoustic measurements.

The purpose of the invention is to expand the region of active sound absorption towards low frequencies.

FIG. 1 shows a wedge sound absorber; in fig. 2 - the same, longitudinal section.

The sound-absorbing element includes a frame 1, made of plastic, wooden slats, impregnated with flame retardants, or from light alcuminic corners. The frame 1 is filled with sound-absorbing materials 2 and 3. As material 2, a material can be rigid, for example, from mineral wool, basalt micro thin fiber (BMTV), basalt cardboard, etc., which simultaneously plays the role of a supporting rod. On top of the rigid material 2 is glued, for example, with the help of a polyvinyl acetate emulsion, soft material 3, for example, a terrestrial basalt fiber BSTV. Material 3 may be absent when a semi-rigid material is used as material 2.

The frame 1 is covered with acoustically transparent material 4, which can be EZ-100 TST-6 fiberglass, TST-8, etc., acoustically transparent for high and some part of mid frequencies. The sound absorber can be made in the form of a wedge, pyrax or cone.

Between the sound-absorbing material 3 and the acoustically transparent material 4, closed air cavities 5 are formed, bounded by framework elements.

A wedge sound absorber base 6 of a rigid or semi-rigid material is attached to the barrier surfaces (not shown). Fasteners are made, for example, by specials with a groove, metal bars, and so on.

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The wedge sound absorber works as follows.

The sound wave, falling on the wall of sound absorbers, is partially dispersed at their tops. Under the action of a sound wave, fiberglass 4, rigidly tensioned to frame 1 with reference to sound absorbing material 3, acts as a membrane fixed at a distance from the wall, all points of which oscillate in phase like a piston, moving parallel to itself, causing dissipative losses and thereby increasing the sound absorption coefficient at low frequencies.

The magnitude of sound absorption is significantly influenced by the added (fractile) air masses on both sides of the stretched glass fabric 4.

Opposite sides of fiberglass 4 oscillate in one phase, but excite in the air volumes of the closed cavities 5 protivopollyh oscillations that interfere with each other. As a result, in Cavity 5, the standing waves are set to decay very quickly due to the presence of a closely located sound-absorbing material 3, which also enhances the sound absorption in the low-frequency region.

The propagation of a sound wave in sound absorbing materials 2 and 3 and along them emerges absorption at high, medium and in a certain range of low frequencies. In addition, there is attenuation due to friction at the attachment points.

This wedge sound absorber allows the sound absorption band to be extended to the side of the most difficult to achieve low frequency range and to achieve high sound absorption coefficients in it. At the same time, the length of the sound absorber is reduced, which leads to a reduction in the dimensions of the rhythmic chamber by at least 20%.

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Claims (1)

A wedge sound absorber, including a frame filled with sound-absorbing material and covered with acoustically transparent material, is characterized by the fact that, in order to expand the area of active sound absorption towards low frequencies, the sound-absorbing and acoustically transparent materials are separated by cavities limited by elements frame.