SOUND-ABSORBING ROOF CONSTRUCTION OF A HALL HAVING REDUCED REVERBERATION TIME

Abstract

The invention relates to a sound-absorbing roof construction of a hall (01) with walls (02), several roof trusses (03) resting at least at their ends on the walls (02) and with a sound-reflecting roof cladding (06) carried by the roof trusses (03). On the side faces of several of the roof trusses (03) there are absorber strips (04) which are composed of sound absorber elements. A sound-reflecting section of the roof cladding (06) extends between adjacent roof trusses (03) with the absorber strips (04) with a width that is at least twice the average height of the roof trusses (03).

The invention also relates to a sound absorber arrangement with sound absorber elements which are arranged in a hall (01) with walls (02) and a roof structure which closes the hall upwards, the roof structure comprising a plurality of roof trusses (03) and a roof cladding (06) carried by them.

According to the invention, absorber strips (04) are attached to the two side surfaces of several of the roof trusses (03), which are composed of sound absorber elements arranged in a row.

Finally, the invention relates to a hall (01) with reduced reverberation time, which uses the sound absorber arrangement.

Claims

1. Sound-absorbing roof construction of a hall with walls, several roof trusses resting at least at their ends on the walls and with a sound-reflecting roof cladding carried by the roof trusses, wherein on the side surfaces of several of the roof trusses absorber strips are attached, which are composed of sound absorber elements, wherein a sound-reflecting section of the roof cladding extends between adjacent roof trusses with the absorber strips with a width which is at least twice the average height of the roof trusses.

2. Sound-absorbing roof construction according to claim 1, wherein the absorber strips substantially completely cover the side surfaces of all roof trusses lying in the interior of the hall.

3. Sound-absorbing roof construction according to claim 1, wherein further absorber strips run along the upper edge of the walls and/or between adjacent roof trusses in the roof construction.

4. Sound-absorbing roof construction according to claim 1, further comprising an acoustically hard reflection wall is arranged between the absorber strips located opposite one another on the same roof truss which is located between the upper flange and the lower flange of the roof truss

5. Sound-absorbing roof construction according to claim 4, wherein an air gap remains between the absorber strips and the reflection wall.

6. Sound-absorbing roof construction according to claim 1, wherein the sound absorber elements of the absorber strips have a thickness of 20-65 mm, preferably 25 mm.

7. Sound-absorbing roof construction according to claim 1, wherein the sound absorber elements of the absorber strips have a length-specific flow resistance in the range 7-15 kPa*s/m.sup.4.

8. Sound-absorbing roof construction according to claim 1, wherein the sound absorber elements consist of a non-ductile foam, in particular a glass-based foam, which comprises expanded glass granulate.

9. Sound-absorbing roof construction according to claim 8, wherein the sound absorber elements are made of expanded glass granulate with a grain size of 0.25-4 mm, the granulate being sintered in plate form or being bonded with added binder, and the length-specific flow resistance being in the range 9-11 kPa*s/m.sup.4.

10. Sound-absorbing roof construction according to claim 1, wherein the roof trusses are spaced apart from one another by more than four times their mean height.

11. Sound-absorbing roof construction according to claim 1, wherein the area occupied by the absorber strips on the side faces of the roof trusses is smaller than the projected area of the roof cladding.

12. Sound-absorbing roof construction according to claim 1, wherein the roof cladding, which extends between the side surfaces of the roof trusses covered with absorber strips, is not covered with sound-absorbing material.

13. Sound absorber arrangement comprising a plurality of sound absorber elements which are arranged in a hall with walls and a roof structure which closes the hall upwards, the roof structure having a plurality of roof trusses resting on the walls and a roof cladding supported by the roof trusses, wherein absorber strips, which are composed of the sound absorber elements, are attached to the two side surfaces of several of the roof trusses, the roof cladding with absorber strips located between the roof trusses extending with a width that is more than twice the height of the absorber strips.

14. Hall with reduced reverberation time, wherein it comprises a sound-absorbing roof structure according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further details and advantages of the sound absorber arrangement according to the invention and the hall equipped therewith result from the following description of a preferred embodiment with reference to the drawing. Shown are:

[0037] FIG. 1 is a not-to-scale ceiling view of a first embodiment of a hall according to the invention with reduced reverberation time;

[0038] FIG. 2 is a schematic diagram of the sound wave course on a roof cladding and an absorber strip which is attached to a roof truss;

[0039] FIG. 3 is a not-to-scale ceiling view of a second embodiment of a hall with reduced reverberation time;

[0040] FIG. 4 is a detailed view of the arrangement of the absorber strip on the roof truss in two subsequently attached embodiments;

[0041] FIG. 5 is a detailed view of the arrangement of the absorber strip on the roof truss in two integrated embodiments;

[0042] FIG. 6 is a diagram to show measured values of the reverberation time in differently configured halls over a wide frequency range.

DETAILED DESCRIPTION OF THE INVENTION

[0043] FIG. 1 shows a not-to-scale ceiling view of a hall 01 according to the invention with reduced reverberation time. The floor area of the hall extends, for example, to 21.5 m 17.5 m. The hall is equipped with a sound absorber arrangement according to the invention, which is designed as a sound-absorbing roof structure. Hall 01 has walls 02 and three interior roof trusses 03, which carry a roof cladding 06 (FIG. 2). Absorber strips 04 are attached to the side surfaces of the roof trusses 03 and essentially cover the entire side surfaces. The roof trusses covered on both sides with absorber strips are spaced about 5.4 m apart in the example shown. There is approximately the same distance between the end walls and the next roof truss. Between the roof trusses 03, sections of the roof cladding 06 extend that are sound-resistant and whose width is more than twice the average height of the roof trusses.

[0044] Each absorber strip 04 consists of one or, preferably, a plurality of sound absorber elements made of a non-ductile foam, preferably a glass-based foam with a proportion of expanded glass granulate. This material is well suited for sound insulation and is easy to process. The sound absorber elements have, for example, an absorption coefficient of =0.4.

[0045] The absorber strip has a width that is adapted to the height of the roof truss and a thickness of, for example, 25 mm. The absorber strip 04 is preferably plate-shaped. To form an absorber strip, several sound absorber elements are strung together with little or no space between. Small distances between the sound absorber elements have a marginal effect on the acoustic damping result.

[0046] FIG. 2 shows in simplified form the absorber strip 04 arranged on the roof truss 03. It can be seen that the roof cladding 06 rests on the roof truss 03 and the absorber strip covers the side surface of the roof truss essentially in its entire height. The reflections of diffuse sound waves occurring on the roof cladding 06 are shown in a very simplified manner by means of arrows. The incident sound waves are reflected on the roof cladding and directed into the absorber strips, whereby a particularly good absorption effect is achieved by means of the absorber strips 04.

[0047] FIG. 3 shows a not-to-scale ceiling view of a second embodiment of Hall 01 with reduced reverberation time. The floor area of the hall is again 21.5 m17.5 m. In addition to the three inner roof trusses 03, further absorber strips 07 are arranged here at the upper ends of the end walls and on the side walls between the roof trusses.

[0048] FIG. 4 shows a simplified cross-sectional view of the roof truss 03, which has an upper flange 08, a lower flange 09 and a stiffening framework 10 between them. In this case, retaining profiles 11 are attached to the roof truss for fastening the absorber strips 04. On the left side of the figure, the absorber strip is held between an upper and a lower holding profile 11, which are each fastened to the upper and lower flange. As shown on the right-hand side of the figure, a holding profile 11 can alternatively be used, which is only attached to the upper flange 08 and yet engages around the absorber strip on its upper edge and lower edge. In this case, the holding profile 11 has a sound-open rear side 13. In preferred embodiments, between the two absorber strips 04 located opposite one another on the roof truss and which are sound-open on the rear, there is a sound-reflecting reflection wall 12 which is positioned between the side surface of the roof truss and the absorber strip in order to return the sound waves penetrating the absorber strips back into the absorber strips. An air gap preferably remains between the absorber strip and the reflection wall 12, which leads to a further diffraction of the sound waves, which has a positive influence on absorption due to interference and impedances that occur.

[0049] FIG. 5 shows two further design options for the arrangement of the absorber strips 04 on the roof truss 03. These variants are particularly suitable if the absorber strips are not attached to the roof trusses only after the hall has been completed, but the sound-absorbing equipment of the roof trusses is already carried out during the construction phase, preferably already during the manufacture of the roof trusses. For this purpose, the absorber strips 04 are preferably integrated into the roof trusses 03. The absorber strip is inserted between the upper flange 08 and the lower flange 09 on the left-hand side of the illustration in FIG. 5, so that holding profiles can be dispensed with. The absorber strip can either be attached to the supporting structure 10 and/or to the upper and lower flange. On the right side of the illustration, a first section of the absorber strip 04 is again arranged between the upper and lower flange, while further sections are attached in the double-T-shaped profiles of the upper and lower flange. This increases the usable absorber area and also improves the visual design.

[0050] FIG. 6 shows a diagram of several measured value curves for the reverberation time over a wide frequency range. The individual curves were recorded in the same hall with a base area of 21.5 m17.5 m and a height of 4.9 m.

[0051] Curve 1)shown as a dash-dot line without markingshows the course of the reverberation time in the original hall, i.e. without installing the sound absorber arrangement. The reverberation time averages 1.52 s and is therefore significantly higher than the value of 1.1 s required by DIN 18041 for speech environments (dashed line).

[0052] Curve 2)shown as a full line with a square markingshows the reverberation time after installation of the absorber strips according to the arrangement shown in FIG. 1 on the three roof trusses inside. The absorber strips in this case have a width of 630 mm. The reverberation time is reduced evenly across all frequencies to an average of 0.93 s.

[0053] Curve 3)shown as a dashed line with diamond markingsshows the reverberation time in the hall if, in addition to the absorber strips on the roof trusses, further absorber strips with a width of 630 mm on the side and end walls are attached which correspond to those in the embodiment shown in FIG. 3. The acoustic absorption performance is only slightly improved by the additional installation. The reverberation time is 0.86 s.

[0054] Curve 4)shown as a solid line with a triangle markingshows the reverberation time in the hall again in accordance with the arrangement according to FIG. 1. Absorber strips are only on the three roof trusses on the inside. However, the width of the absorber strips was doubled to 1240 mm, while the thickness remained the same. It can be seen that a significantly reduced reverberation time of 0.66 s can be achieved in this way.

[0055] The effect that can be achieved by the sound absorber arrangement according to the invention becomes particularly clear when the absorption surfaces required are compared to the absorption surface that would be required mathematically (using Sabine's formula) if the same absorption performance is to be achieved by a closed absorption surface running parallel to the floor surface. The values are shown in the table below:

[0056] Absorber area (a=0.40) and reverberation time

TABLE-US-00001 Reverberation Absorber surface time calculation acc. to 250-4,000 Hz Sabine formula Built-in sec. m.sup.2 m.sup.2 % Comment 1.52 0 without acoustic installation according to DIN 1.1 189 18041 0.93 314 88 = 28 0.86 379 137 = 36 plus all-round installation 0.66 644 174 = 27

[0057] It is clear from the values mentioned in the table that the required absorber area can be reduced to <30% of the area calculated according to the prior art by the arrangement according to the invention.