DE29813397U1 - Noise protection of a microphone - Google Patents

Description

Noise protection of a microphone

The invention relates to an interference noise protection device, in particular a wind noise protection device for putting over a microphone, which consists of a fine-pored, open-pored foam jacket with a wall thickness of at least 1 cm and whose jacket surface is coated with plastic fiber flakes.

Such flocked foam covers for microphones are well known. This soft cover serves to avoid or attenuate low-frequency wind noise and to dampen high-frequency crackling noises and hissing sounds; in the rest of the spectral range, however, they show very little dampening, so that the overall system of microphone and cover achieves a high quality of conversion of recorded sounds and spoken language. The directional effect of directional microphones, which are usually made up of several microphone sensors or are equipped with sound conductors and/or reflectors, is only slightly influenced by the all-round foam cover.

Furthermore, microphone foam covers without fiber flocking are known, which provide slightly less attenuation of the high frequencies than with flocking, but also suppress the generation of wind noise.

The object of the invention is to improve the noise protection so that it further increases the implementation quality of the acoustic events.

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The solution is that only parts of the shell surface are coated with the plastic fiber flakes.

Preferably, the rear area of the jacket surface, which is usually further away from the sound source, is flocked. This means that the sound waves of the sound source up to the highest recordable frequencies are accessible to the microphone largely undamped, and noise arriving from the rear, in particular echoes from objects close to the microphone, are dampened. This improves the directivity of the microphone arrangement depending on the frequency and increases the sound fidelity and intelligibility of recorded and later reproduced speech.

Preferably, the outer surface is flocked over 1/4 to 3/4 of its axial extension parallel to the microphone longitudinal axis, and the thickness of the flocking layer is preferably 1-2 mm.

However, if the microphone is intended for recording acoustic events in concert halls, it is often desirable to record the orchestral sound without the higher frequency background noise that occurs in the orchestra room, but with good room echo conversion. In this case, the front part of the jacket is equipped with the flocking and the rear part is left free. The acoustic effect of the partial flocking is similar to the optical effect of an anti-reflective coating on a lens.

Partial flocking can be carried out directly with a stencil covering the surface of the jacket to be kept free or using the well-known flock layer transfer process. In this case, a

A detachably applied, thermally activated adhesive layer is flocked and the flock fleece produced in this way is then placed on the surface of the casing. The adhesive is then activated using an increased temperature so that it adheres to the foam and binds the flock layer there. The activation temperature of the adhesive is selected and controlled during activation so that the foam does not noticeably shrink or harden.

The flock layer transfer process can also be used to attach emblems, as these can be easily created by flocking with appropriate stencils on the adhesive layer and can be easily transferred. Such flock fleece emblems can be sealed onto the foam surface as well as onto an already flocked surface. In addition to the technical effect, this offers a wide range of design options, as both the foam and the flock layer and the emblems can be colored in different colors.

Preferred examples are shown in Figures 1 to 4.

Fig. 1 shows an axial section of a first embodiment;

Fig. 2 shows a side view of a second embodiment; Fig. 3 shows a cross section A-A of the first type; Fig. 3 shows a cross section of the second type.

Figure 1 relates to a version of the noise protection jacket 1 with flocking on the back. Inside it there is a coaxial recess 2 that is open at one end to accommodate a microphone M. This is

2 ¹

including a support extension H, is tightly enclosed by a 1-2 cm thick, fine-pored, open-pored foam layer 10. In the rear third of the axial extension on the support side, a flocking layer 11 made of plastic fiber material, approximately 1-2 mm thick, is applied to the foam casing 10. It has such a density that the foam surface is still slightly translucent, even if it is of a different color. The entire shape of the casing 1 has rounded contours so that no eddies are created in the air passing by.

Figure 2 shows a side view of a microphone casing IA, the foam casing 10 of which is covered with a flocking layer HA in the front area over approximately 2/3 of the axial length. In addition, emblems 12, 13 made of flock fleece are used on the foam surface as well as on the larger-area flocking layer HA. These emblems 12, 13 do not exhibit any significant acoustic properties due to their structures and small size. The thin adhesive layer T of the transfer material is dissolved so much by the thermal treatment and is so tightly bound to the adjacent materials that it is permeable to air, and therefore does not cause interference.

Instead of the emblems shown, stripe or hole patterns can also be produced and applied, which then preferentially dampen a certain frequency range according to their structural dimensions.

Figure 3 shows a cross section A-A through Figure 1, where the foam casing 10 has a circular outer contour. The relatively thick foam casing has a thin flake layer 11 all around it. The elastic foam 10 encloses the microphone M without a

Intermediate space.

Figure 4 shows an alternative cross-section of the foam casing 1OA, which is polygonal and has rounded edges. It is evenly surrounded by the flock fleece HA. Other shapes of the foam casing can be created freely without having to accept any significant change in the acoustic effectiveness, but rounded edges should be provided if possible.

Claims (8)

Protection claims 1. Noise protection (1), in particular wind noise protection to be placed over a microphone (M), which consists of a fine-pored open-pored foam casing (10) of at least 1 cm wall thickness and whose jacket surface is coated with synthetic fiber flakes (11, HA, 12, 13), characterized in that only partial areas of the jacket surface are coated with the synthetic fiber flakes (11, HA, 12, 13). 2. Noise protection according to claim 1, characterized in that the plastic fiber flakes (11, HA) cover the jacket surface in the microphone axis direction over 1/3 to 2/3 of its length. 3. Noise protection according to claim 2, characterized in that the plastic fiber flakes (11, HA) are arranged on the jacket surface to the rear or front of the microphone (M). 4. Noise protection according to claim 2 or 3, characterized in that the plastic fiber flakes (12, 13) are at least partially structured and/or applied as emblems on the casing surface directly or on the plastic fiber flake layer (11, HA). 5. Noise protection according to one of the preceding claims, characterized in that the layer of plastic flakes (11, HA, 12, 13) has a thickness of 1 - 2 mm. 6. Noise protection according to one of the preceding claims, characterized in that the plastic fiber flakes (11, HA) are flocked as a flake layer directly onto the casing surface. 7. Noise protection according to one of claims 1 to 5, characterized in that the plastic fiber flakes (12, 13) are fixed with a porous transfer adhesive layer to the jacket surface directly or on a plastic fiber flake layer (11, HA). 8. Noise layer according to one of the preceding claims, characterized in that the foam casing (10) and the plastic fiber flakes (11, HA, 12, 13) are of different colors.