AU9045898A - Acoustically resistant wall - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for Service: Invention Title: CSR LIMITED of 1 O'Connell Street, Sydney, NSW, 2000, Australia David Came of CSR Building Materials Research and Development, 376 Victoria Street, Wetherill Park, NSW, 2164 H.R. HODGKINSON CO.

Patent Trade Mark Attorneys Level 3, 20 Alfred Street MILSONS POINT NSW 2061 ACOUSTICALLY RESISTANT WALL Details of Associated Provisional Application: Nos: PP0201 filed 4 November 1997 The following statement is a full description of this invention, including the best method of performing it known to us.

BACKGROUND TO THE PRESENT INVENTION: The present invention relates to acoustically resistant walls and, in particular to acoustically resistant walls for use as dividing walls between rooms or halls such as auditoriums or cinema theatres. Acoustically resistant walls for use in cinemas ("cinema walls") are specially constructed so as to minimise the amount of sound transmitted through the wall, or, in other words to maximise the Sound Transmission Loss The acoustically resistant wall of the present invention is able to achieve a high STL whilst overcoming a number of the disadvantages of the prior art.

PRIOR ART: Most existing cinema walls consist of a central concrete or staggered steel structure with multiple layers of plasterboard affixed thereto by acoustically isolating mounts or clips.

An example of such a clip is that produced by Boral Australia Gypsum Limited, as disclosed in AU65859/96 ("the Boral Application"). The Boral Application discloses a lining board mounting system including a clip for a furring channel to which the lining board is secured.

The clip includes an externally screw threaded fastener which is engaged with and projects from the clip, an elastomeric sleeve on the fastener, a nut on the fastener to axially compress and thereby radially expand the sleeve in a wall bore, and an elastomeric pad to space and thereby acoustically isolate the clip from the wall when the system is secured on the wall.

Existing methods of cinema wall construction have a number of disadvantages including but not limited to the following: Firstly, the central concrete or staggered steel supporting structures, which are needed to support the isolated plasterboard surfaces, require a large amount of concrete and or steel for their construction. This has disadvantageous implications both in terms of the cost of materials required to build such walls and the difficult and time consuming nature of their construction.

Secondly, cinema walls of the prior art which require such wide central supporting structures must be made very wide so that there is sufficient air space between the central supporting structure and the outer panels to minimise the sound resonance which occurs within the wall itself. The burdensome width of these walls reduces the floor space available to cinema patrons and decreases the profitability of such cinema enterprises.

Thirdly, a number of cinema walls of the prior art require many layers of plasterboard on their outer surfaces in order to attain the STL levels required for cinema complexes. Consequently, such structures require an excessive amount of plasterboard for their construction which results in large material and labour costs.

It is therefore a non-limiting object of the present invention to provide an acoustically resistant wall which achieves a high sound transmission loss using less concrete and steel, is of a reduced width, and is more easily constructed than the acoustically resistant walls of the pnrior art.

THE PRESENT INVENTION: According to one aspect of the present invention there is provided an acoustically resistant wall including a plurality of central supporting members, a plurality of horizontally aligned structural members, a plurality of vertically aligned structural members and at least one surface member. Each of the horizontally aligned structural members is attached to at least one of the central supporting members by at least one mount. This attachment is made in such a way that at least part of each of the horizontally aligned structural members protrudes beyond a sideways extremity of the central supporting members. The horizontally aligned structural members are fixedly connected to the vertically aligned structural members which, in turn, are fixedly connected to the surface member.

According to one aspect of the present invention there is provided an acoustically resistant wall as described above wherein each member of a first set of the horizontally aligned structural members at least partially protrudes beyond a first sideways extremity of the central supporting members. These member of the first set of horizontally aligned structural members are fixedly connected to at least one of a first set of vertically aligned structural members which, in turn, are fixedly connected to a first surface member. Each member of a second set of horizontally aligned structural members at least partially protrudes beyond a second sideways extremity of the central supporting members. These member of the second set of horizontally aligned structural members are fixedly connected to at least one of a second set of vertically aligned structural members which, in turn, are fixedly connected to a second surface member. The structural and surface members are arranged such that the area between the first and second surface members defines a central cavity.

According to a further aspect of the present invention there is provided an acoustically resistant wall as described above wherein members of the first and second sets of horizontally aligned structural members are vertically spaced up the height of the central supporting members in an alternating manner.

According to yet another aspect of the present invention there is disclosed an acoustically resistant wall including a plurality of laterally spaced steel columns, a plurality of vertically spaced, horizontally aligned girts, a plurality of mounts, a plurality of laterally spaced, vertically aligned top hat battens, two surface members, a central cavity and at least one layer of insulating material. The surface members of the acoustically resistant wall include at least one layer of fire graded plasterboard and are attached to the laterally spaced top hat battens.

The top hat battens are fixedly connected to the vertically spaced, horizontally aligned girts.

The girts are fixedly connected to the laterally spaced steel columns by means of the plurality of mounts.

According to a further aspect of the present invention there is provided an acoustically resistant wall as described above wherein the girts are fixedly connected to the laterally spaced steel columns by means of a plurality of acoustically isolating mounts on one side, and by means of a plurality of non-acoustically isolating mounts on another side. The girts are attached to the steel columns so that each girt protrudes beyond one side, but not the other, of the steel columns. The insulating material is positioned within the central cavity between each girt and the top hat batten on the opposite side of the central cavity.

According to an additional aspect of the present invention there is provided a method of constructing an acoustically resistant wall as described above, including the steps of: fixing the supporting members to the floor; attaching the horizontally aligned structural members to the supporting members by the mounts; attaching the vertically aligned structural members to the horizontally aligned structural members; and attaching the at least one surface member to the vertically aligned structural members.

According to yet another aspect of the present invention there is provided a method of constructing an acoustically resistant wall as described above, including the additional step of securing channel means to the floor and inserting the bases of the vertical structural members into the channel means.

According to yet a further aspect of the present invention there is provided a method of constructing an acoustically resistant wall as described above, including the additional step of sealingly connecting the surface members and the channel to the floor using sealing means.

PREFERRED EMBODIMENT: One non-limiting embodiment of the present invention will now be described with reference to the drawings in which: Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Is a sectional elevational view of the acoustically resistant wall; Is an exploded sectional elevational view of an acoustically isolating mount; Is a close up of a sectional elevational view of the circled area marked 2' in Figure 1; Is an isometric view of the furring channel; Is a layered skeletal elevational side view of the acoustically resistant wall; Is a sectional plan view of the acoustically resistant wall; and Is a close up of a layered skeletal elevational side view of the acoustically resistant wall.

As seen in Figure 1, the acoustically resistant wall comprises two surface members 3), a central cavity a plurality of laterally spaced top hat battens a plurality of vertically spaced, horizontally aligned girts 7, 8, a plurality of isolating mounts at least one layer of insulating material and a plurality of laterally spaced steel columns (12).

The outer surface members 3) of the acoustically resistant wall of the preferred embodiment comprise three layers of fire graded plasterboard (13, 14, 15), such as 16 mm Fyrechek made by CSR Limited. As seen in Figure 7, the layers of fire graded plasterboard (13, 14, 15) are attached to the battens preferably by means of self tapping screws As can be seen in Figure 5, the first layer of plasterboard (15) is screwed to the battens and the second layer of plasterboard (14) is then overlaid on top of the first layer of plasterboard The third layer of plasterboard (13) is then overlaid on top of the second layer of plasterboard (14) so that the joints (16, 17, 18) of each of the layers of plasterboard (15, 14, 13) are staggered, preferably with a minimum of 300 mm between joints (16, 17, 18).

As can be seen in Figure 3, the battens are secured within a furring channel (19) preferably made by Rondo Building Services Pty Ltd ("Rondo"). The furring channel (19) is fixedly attached to a concrete slab (20) by furring channel connective means (not shown) which pass through a layer of high density glass wool (21) positioned between the furring channel (19) and the concrete slab The layers of plasterboard (13, 14, 15), attached to the battens rest upon the concrete slab (20) with sealing means (22) positioned in the join between the layers of plasterboard (13, 14, 15) and the concrete slab Figure 4 shows an isometric view of the furring channel (19).

The laterally spaced top hat battens (19) are connected to the vertically spaced, horizontally aligned girts 7) preferably by means of self-tapping screws (not shown).

As can be seen in Figure 1, the girts 7) are preferably connected to the steel columns (12) by means of acoustically isolating mounts (10, 24) such as the M107-40 and M104-70 isolating mounts made by Mackay Consolidated Industries ("Mackay"). The vertically spaced, horizontally aligned girts 9) are preferably attached to the steel columns (12) by means of non acoustically isolating mounts (25, 26). However, if the concrete slab (20) is not isolated between the adjoining cinemas, then the non acoustically isolating mounts (25, 26) should be replaced by acoustically isolating mounts (such as those made by Mackay) in order to achieve the requisite STL levels.

The girts are connected to the steel columns (12) so that one side of the girts 7) protrudes beyond one edge (27) of the steel columns (12) in order that the battens on one side of the wall do not come in contact with the steel columns Similarly, the girts 9) are attached to the steel columns (12) so as to protrude beyond another side (28) of the steel columns (12) so as to prevent contact between the battens (23) on the other side of the wall and the steel columns (12).

As can be seen in Figure 1, the girts 7) are vertically spaced in an alternating manner in relation to the girts Preferably, the distance between the centres of opposite girts, such as 6 and 8, and such as 7 and 9, is no less than 300 millimetres. This is so that the sonic resonance between the girts 7, 8, 9) within the central cavity is minimised.

channel (19) to the concrete slab (20) and inserting the bases of the vertically aligned top hat battens into the furring channel (19).

The preferred method of constructing the acoustically resistant wall of the preferred embodiment, as described above, may further include the additional step of sealingly connecting the surface members and the furring channel (19) to the concrete slab using sealing means.

ACOUSTIC TESTS CARRIED OUT The acoustically resistant wall of the preferred embodiment, as described above, was subjected to a transmission loss test by the National Acoustic Laboratories in September of 1997. A test sample of the wall was constructed in a testing opening between two reverberation rooms at the NAL acoustic test facility.

The sound transmission class of the wall was determined by a program of measurements carried out according to the procedures and methods of Australian Standard 1191-1985, "Acoustics-Method for the laboratory measurement of airborne sound transmission loss of building partitions".

A rating of STC 77 (dB) was measured for the wall test sample.

ACOUSTIC TEST RESULTS: A complete set of measurements and calculation for the determination of the Sound Transmission Loss of the test wall sample was calculated and is presented numerically and graphically on the spreadsheet annexed hereto and marked with the letter A summary of these results, rounded off to the nearest Decibel as required by AS1191, is as follows:

I

Transmission Loss Results 1/3 Octave Centre STC77 Wall Criteria Test Sample Difference Frequency (Hz) (dB) Attenuation (dB) (dB) 100 -56 125 61 58 -3 160 64 64 200 67 66 -1 250 70 67 -3 315 73 73 400 76 75 -1 500 77 72 630 78 71 -7 800 79 76 -3 1000 80 78 -2 1250 81 81 1600 81 87 2000 81 88 2500 81 89 3150 81 89 4000 81 88 5000 82 The determination of the STC for a test sample requires a comparison of its sound transmission loss with a series of values for each transmission class rating listed in the STC tables at each 1/3 octave band centre frequency, from 125 Hz to 4,000 Hz. The correct Sound Transmission Class rating determined by these tables is reached when either or both of the following requirements are met: the test sample transmission loss at any frequency in the range 125 Hz to 4,000 Hz must not lie more that 8 dB below that of the STC graph; the total sum of the test sample values lying below the STC graph values at the same frequency must not add up to more than 32 dB.

Details of the testing procedure carried out appear below.

TESTING PROCEDURE: The test sample wall was fitted in an aperture between the reverberation rooms and the aperture perimeter was carefully sealed with a thick sealing compound to avoid acoustical leakage between the two reverberation rooms.

After the "drying" time had elapsed, the sample was performance measured according to the transmission loss methods and procedures of Australian Standard AS 1191-1985, "Acoustics Method for laboratory measurement of airborne sound transmission loss of building partitions".

The STC value was determined according to procedures specified in AS 1276-1979, ("Methods for determination of sound transmission class and noise isolation class of building partitions").

REVERBERATION

ROOMS:

Each acoustical test facility reverberation room is approximately 200 cubic metres in volume and is fully air conditioned by a special temperature and humidity controlled and acoustically attenuated air conditioning system. The floors are pentagonally shaped. The ceilings are inclined to the plane of the floors, and the overall construction ensures that internal opposite facing surfaces are not parallel. Reverberation room construction detail conforms with the sound field diffusivity, volume and shape requirements of International Standardisation Organisation document IS0354 1985 "Acoustics, Measurement of sound absorption in a reverberation room".

Both reverberation rooms are inside separate isolating rooms which serve as plenum chambers. This construction ensures freedom from flanking noise transmission problems even when very high acoustical sound pressure levels are generated inside either reverberation room.

A sample testing space of approximately 10 square metres is located within an opening in the common wall between the plenum chambers. This wall is part of the sound shell construction and effectively isolates the sample from any vibrational energy which may be generated inside either reverberation room.

Exposure of either side of any test sample in this test space to a sound field is achieved by apertures in each reverberation room wall which align with the opening in the common wall of the plenum chambers. Acoustical sealing at the location of the openings between the reverberation rooms and the wall holding the test sample is achieved by means of compliant, high transmission-loss gaskets installed between the reverberation rooms and the common wall between the plenum chambers.

The 300 mm thick walls, floor and ceiling of all three rooms and plenum chambers are made from a heavily reinforced, high density concrete which was poured on site during the construction of the Acoustical Test Facility. The reverberation rooms are vibrationally suspended on damped, high tensile springs resting on neoprene rubber. The entire suspension assembly forms a two-pole resonant suspension system which is tuned below The complete mounting system of springs, dampers and high compliance acoustical seals around the test apertures ensures negligible vibrational coupling between the reverberation rooms, or interference from outside vibrational sources, for all frequencies within the operating range of the two reverberation rooms. Entry to both reverberation rooms and plenum chambers is by means of bi-parting doors.

Additional sound diffusion within the rooms is achieved by means of non-parallel room surfaces coupled with the careful placing of randomly-oriented, suspended panels (19mm Factors determining sound level measured in the receive room are: 1. sound pressure level in the send room; 2. transmission loss of the sample and; 3. reverberation time of the receive room.

Sets of measurements were obtained at six low height positions and six high positions in both the "receive" and the "send" rooms. Reverberation time in the "receive" room was obtained according to the procedures of AS 1045 ("Acoustics-Measurement of Sound Absorption in a Reverberation Room").

The complete measurement cycle for the test therefore comprised a total of twenty four sets of recordings taken at six combinations of the measurement positions of microphone and loudspeaker. Each set of measurements contained a recording of third octave frequency bands between 100Hz and 5000Hz (eighteen in total). During the measurement procedure, care was taken to check if the measurement to background noise level margin exceeded 10dB before determination of the STC value was made.

Acoustical calibration of each microphone was repeated at completion of the testing cycle to verify accuracy of results.

Although the invention has been described herein with reference to a preferred embodiment including drawings, it will be recognised by persons skilled in the art that numerous variations and modifications may be made to the invention as broadly described herein without departing from the overall spirit and scope of the invention.

Claims (31)

1. An acoustically resistant wall including, a plurality of central supporting members, a plurality of horizontally aligned structural members, a plurality of vertically aligned structural members and at least one surface member; wherein each of said horizontally aligned structural members is attached to at least one of said central supporting members by at least one mount so that at least part of each of said horizontally aligned structural members protrudes beyond a sideways extremity of said at least one central supporting member and are fixedly connected to at least one of said vertically aligned structural members which, in turn, are fixedly connected to said at least one surface member.

2. An acoustically resistant wall as claimed in Claim 1, wherein each member of a first set of said horizontally aligned structural members at least partially protrudes beyond a first sideways extremity of said at least one central supporting member, and are fixedly connected to at least one of a first set of vertically aligned structural members which, in turn, are fixedly connected to a first surface member; and each member of a second set of horizontally aligned structural members at least partially protrudes beyond a second sideways extremity of said at least one central supporting member, and are fixedly connected to at least one of a second set of vertically aligned structural members which, in turn, are fixedly connected to a second surface member; such that the area between said first and second surface members defines a central cavity.

3. An acoustically resistant wall as claimed in Claim 2, wherein members of said first and second sets of said horizontally aligned structural members are vertically spaced up the height of said central supporting members in an alternating manner.

4. An acoustically resistant wall as claimed in any preceding claim, wherein said at least one mount is an acoustically isolating mount.

An acoustically resistant wall as claimed in any preceding claim, wherein said at least one mount is a non-acoustically isolating mount.

6. An acoustically resistant wall as claimed in any preceding claim, wherein said central cavity contains insulating means.

7. An acoustically resistant wall as claimed in any preceding claim, wherein said plurality of central supporting members includes a plurality of vertically aligned, laterally spaced, steel columns.

8. An acoustically resistant wall as claimed in any preceding claim, wherein said plurality of horizontally aligned structural members includes a plurality of horizontally aligned, vertically spaced girts.

9. An acoustically resistant wall as claimed in any preceding claim, wherein said plurality of vertically aligned structural members includes a plurality of vertically aligned, laterally spaced, top hat battens.

An acoustically resistant wall as claimed in Claim 9, wherein said top hat battens have bases and said bases sit within a channel means which is secured to a floor.

11. An acoustically resistant wall as claimed in Claim 10, wherein said channel means includes a furring channel.

12. An acoustically resistant wall as claimed in any preceding claim, wherein said at least one surface member includes at least one layer of fire graded plasterboard.

13. An acoustically resistant wall as claimed in Claim 12, wherein said at least one layer of fire graded plasterboard includes three layers of 16mm fire graded plasterboard.

14. An acoustically resistant wall as claimed in either of Claims 12 or 13, wherein said layers of fire graded plasterboard are positioned so that joints between adjoining layers of plasterboard are staggered.

15. An acoustically resistant wall as claimed in Claim 14, wherein said joints are staggered by at least 300mm.

16. An acoustically resistant wall as claimed in any one of Claims 10 to 15, wherein said at least one surface member and said channel means are sealingly connected to said floor by sealing means.

17. An acoustically resistant wall as claimed in Claim 16, wherein said sealing means includes at least one layer of high density glasswool.

18. An acoustically resistant wall as claimed in any one of Claims 6 to 17, wherein at least part of said insulating means is positioned between at least one of said first set of horizontally aligned structural members and said second surface member.

19. An acoustically resistant wall as claimed in any one of Claims 6 to 18, wherein at least part of said insulating means is positioned between at least one of said second set of horizontally aligned structural members and said first surface member.

An acoustically resistant wall according to any one of Claims 6 to 19, wherein said insulating means is woven within said central cavity between said first and second surface members and said alternately spaced members of said first and second sets of said horizontally aligned structural members.

21. An acoustically resistant wall as claimed in any one of Claims 6 to 20, wherein said insulating means includes at least one layer of insulating material.

22. An acoustically resistant wall as claimed in Claim 21, wherein said insulating material is a glasswool building blanket.

23. An acoustically resistant wall as claimed in any one of Claims 2 to 22, wherein said central cavity is at least 375mm wide so as to minimise the sonic resonance within said wall.

24. An acoustically resistant wall as claimed in any one of Claims 3 to 23, wherein the vertical distance between said alternately spaced horizontally aligned structural members is no less than 300mm.

An acoustically resistant wall as claimed in any preceding claim, wherein adjacent members of said first set of vertically aligned supporting members are approximately 900mm apart.

26. An acoustically resistant wall as claimed in any preceding claim, wherein adjacent members of said second set of vertically aligned supporting members are approximately 900mm apart.

27. A method of constructing an acoustically resistant wall as claimed in any preceding claim, including the steps of: fixing said supporting members to said floor; attaching said horizontally aligned structural members to said supporting members by said mounts; attaching said vertically aligned structural members to said horizontally aligned structural members; and attaching said at least one surface member to said vertically aligned structural members. 27. A method of constructing an acoustically resistant wall as claimed in Claim 26, including the additional step of securing said channel means to said floor and inserting said bases of said vertical structural members into said channel means.

28. A method of constructing an acoustically resistant wall as claimed in either of Claims 26 or 27, including the additional step of sealingly connecting said surface members and said channel to said floor using sealing means.

29. A method of constructing an acoustically resistant wall as claimed in any one of Claims 26 to 28, including the additional steps of weaving said insulating means within said cavity between said horizontally aligned structural members and said surface members.

An acoustically resistant wall as claimed in any one of Claims 1 to 25, substantially as hereinbefore described with reference to the drawings.

31. A method of constructing an acoustically resistant wall as claimed in any one of Claims 26 to 29, substantially as hereinbefore described with reference to the drawings. DATED this 30th day of October 1998 CSRL E. by: H.R. HODGKINSON CO. Patent Attorneys for the Applicant