SOUND ATTENUATING CLIP

Technical Field

The present disclosure relates to sound insulation, in particular acoustic clips used to connect building components together. The clip of the present disclosure improves noise insulation in a building by reducing the level of sound and vibrations travelling through the building components.

Background

Buildings are conventionally are made up of living spaces surrounded by building elements such as floors, walls, ceilings and/or brackets. There are a number of variations of types of the floors, walls and ceilings available, such as framed walls using metal or wood. In other examples, the floors, walls and ceilings may be made of bricks, blocks, concrete or reinforced concrete.

In the modem world, noise insulation is becoming of increasing importance because buildings are being built closer together. Also, many buildings that were originally used as houses are being converted to flats so that many people may be present within the building. In doing so, the conversion must comply with Part E building regulations, which relates to sound insulation. However, even with these regulations, noise will still pass from one flat to another. As a result, in the modern world there are more potential sources of noises and so the demand for providing improved noise insulation has increased.

In some known examples, a clip is used to attach a plasterboard to a building element. The clip may include a bracket and a fixture for fixing the bracket to a building element. The clip may hold a furring channel to which a plasterboard may be attached. The clip may include a soft, sound attenuating material between the bracket and the building element to reduce sound vibrations passing between the building element and the plasterboard. The clip may provide some sound insulation between the plasterboard on the inside of the living space or room and the wall and/or ceiling. However, in these known examples, there is still a significant proportion of sound vibrations transmitted through the wall and or ceiling. Therefore, there exists a need to improve noise isolation in buildings. Summary

According to a first aspect of the present invention, there is provided a clip for connecting a furring channel to a building element, the clip comprising: a bracket for receiving a furring channel, wherein the bracket is configured to be connected to the building element via a fixture; and a sound attenuator comprising a first element and a second element, wherein in use, a first part of the first element is at least partially enclosed by the second element and at least the second element is configured to abut the building element, and wherein the second element has an acoustic attenuation property different to an acoustic attenuation property of the first element. The provision of a clip with a sound attenuator having a first element having a first acoustic attenuation property and a second element have a second acoustic attenuation property improves sound insulation within a building. In particular, the clip 100 improves de-coupling from a building element, such as a wall or ceiling to a partition. The use of the first element and second element reduces the ease in which sound energy may travel through the clip.

The use of a sound attenuator including a first element having a first acoustic attenuation property and a second element having a second acoustic attenuation property, different to the first, goes against the conventional teaching of the art because the complexity of the system is increased. However, this dual system provides surprising sound attenuation benefits when compared with clips having a sound attenuator formed of a single element.

In one example, the acoustic attenuation property is based on one or more of: density, elasticity, hardness, stiffness and Young’s Modulus.

In one example, the bracket comprises at least one slot for receiving the furring channel. Further, the bracket may comprise a sheet metal defining a planar surface and a plurality of arms may project away from the planar surface and the at least one slot may be defined by the plurality of arms. In one example, the first part of the first element is configured to be received in a hole in the second element so as to be substantially flush with the second element and abut the building element.

In one example, the second element is substantially located between the first element and the building element.

In one example, the bracket comprises a through-hole for receiving said fixture.

In one example, a second part of the first element of the sound attenuator is located on the opposite side of the bracket to the first part of the first element. Further, the clip may comprise an insert comprising a bushing and a flange; wherein the flange provides a bearing surface for said fixture and the bushing is configured to project through the second part of the first element and the through-hole of the bracket.

In one example, the bracket may comprise at least two indents located either side of the through hole.

In one example, the first element may have a hardness of between 25 to 60 A shore hardness and the second element has a hardness of between 35 to 70 A shore hardness.

In one example, the first element may have a lower hardness compared with the second element.

In one example, the first element and the second element may comprise a rubber polymer.

In one example, the sound attenuator may comprise a fire retardant additive.

In one example, the second element is connected to the first part of the first element via an interference fit.

In one example, the sound attenuator may include a third element located between the first element and the second element and wherein the first element, the second element and the third element each have a different acoustic attenuation property. In one example, the first element and the second element may be modular to enable the first element and/or the second element to be replaced by another first element and/or second element having a different acoustic attenuation property.

In one example, the second element may be shaped to ensure the clip is arranged substantially parallel to the building element.

In one example, the first part of the first element may be substantially cylindrical.

In one example, the second element may be substantially cylindrical.

In one example, the second element is substantially cuboid.

In one example, the first element comprises a second part in the form of a truncated cone to enable it to be pushed through the through hole of the bracket.

In one example, the first part of the first element includes a lip that extends substantially around the perimeter of the first element to enable the second element to be located on the first element.

According to another aspect, there is provided a system comprising: a clip, a furring channel connected to the clip; and a fixture for connecting the clip to a building element.

According to another aspect of the present invention, there is provided a clip for connecting a furring channel to a building element, the clip comprising: a bracket for receiving a furring channel, wherein the bracket is configured to be connected to the building element via a fixture; and a sound attenuator comprising a first element and a second element, wherein in use, a first part of the first element is at least partially enclosed by the second element and at least the second element is configured to abut the building element, and wherein the second element has a hardness different to a hardness of the first element.

According to one example, there is provided a clip for connecting a furring channel to a building element, the clip comprising: a bracket for receiving a furring channel, wherein the bracket is configured to be connected to the building element via a fixture; and a sound attenuator comprising a first element and a second element, wherein in use, a first part of the first element is at least partially enclosed by the second element and at least the second element is configured to abut the building element, and wherein the second element has a physical and acoustic attenuation property different to a physical and acoustic attenuation property of the first element. The first element may have a different hardness, stiffness, density, mass, Young’s modulus, surface area, profile and/or elasticity compared with the second element.

The clip combines more factors from the basic principles of sound attenuation than any prior art and furthermore, these elements are easily customisable for different uses / benefits, as well as being completely recyclable.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 shows an illustrative side view of a clip according to a first example;

Figure 2 shows an illustrative perspective view of the clip according to a first example;

Figure 3 shows an illustrative perspective view of the components of the clip according to a first example;

Figure 4A shows an illustrative side view of the components of the clip according to a first example;

Figure 4B shows an illustrative side view of the first element and the second element of the clip connected together;

Figure 5A shows an illustrative example of two clips located on a building element in the form of a brick wall;

Figure 5B shows an illustrative example of the two clips holding a furring channel;

Figure 6A shows an illustrative side view of an example of a furring channel;

Figures 6B shows an illustrative perspective view of an example of a furring channel;

Figure 7A shows an illustrative example of the side view of the clip with a furring channel connected to the clip; Figure 7B shows an illustrative example of the side view of the clip connected to a building element with a furring channel connected to the clip and a plasterboard connected to the furring channel;

Figure 8A shows an illustrative perspective view of a second example of a clip;

Figure 8B shows an illustrative perspective view of the components of the second example of the clip;

Figure 9A shows an illustrative perspective view of a third example of a clip;

Figure 9B shows an illustrative perspective view of the components of the third example of the clip;

Figure 10 shows an illustrative view of a clip connected to a building element via a fixture

Figure 11 shows a graph of the Sound Reduction Index for a clip having a sound attenuator with only one value of acoustic attenuation property;

Figure 12 shows a graph of the Sound Reduction Index for a clip having a sound attenuator with a first element and a second element having different acoustic attenuation properties; and

Figure 13 shows a comparison of the results of Figures 11 ands 12.

Detailed Description

Soundproofing, sound attenuation and noise reduction through building elements are essentially concerned with energy management. Noise may be transferred from outside of the building into a living space of the building through the vibration of the building elements. One way for reducing the transfer of noise through a building element is to change the vibrational sound energy into other forms of energy, such as heat.

In addition, another way of increasing the sound insulation is to provide an additional layer of building material for the sound to travel through. For example, plasterboard may be used that is spaced apart from a building element to form a void. The plasterboard may be attached to a clip that is connected to a building element. Providing a void means that there is further for the sound vibrational area to travel and there is reduced direct contact between the building element and the inside living space of the building.

One important factor of sound insulation is the mass of the building element and the components, such as the clip and plasterboard, attached to a building element. Typically, on a common single wood stud wall, doubling the number of drywall layers yields 3-5dB of improvement. Mass impedes the transmission of sound vibrations because the larger the mass of the component, the more energy is required to vibrate the component. In contrast, a component with a relatively smaller mass will require less energy in order to vibrate the component. However, simply adding mass is not a workable long term strategy for sound insulation. The addition of mass is a simple method for improving sound insulation. For example, doubling the mass of a solid partition may gain an additional 6dB. However, then to gain a further 6dB improvement, the mass of the whole system needs to be doubled again, which is not practical in building construction.

An additional principal of sound attenuation is mechanical decoupling. In some examples, walls or ceilings may be made up of multiple components or layers. For example, a wall may have a building element in the form of brickwork and plasterboard located away from the wall, which creates a cavity between the building element and the plasterboard. Mechanically decoupling the layers or components of the wall and/or ceiling prevents or reduces vibrations passing directly from one layer to the other layer. Mechanical decoupling may be achieved via one or more of sound attenuation clips, resilient channels, staggered studs and double stud walls. All of these components function by inhibiting the movement of sound vibrations from one side of the wall or ceiling to the other side of the wall or ceiling through mechanical paths (like studs or joists). However, mechanical decoupling is frequency-dependent. If, for example, two pieces of drywall are de-coupled, a natural resonance in the cavity between the two pieces of drywall is created. At vibrational frequencies close to the resonant frequency, the effect of the mechanical de-coupling will be reduced and vibrations may still be transferred from between the two pieces of the drywall. Treating the cavity with an absorption material, such as mineral wool, will alter and reduce the resonant frequency of the wall. If a first side of the building element is mechanically decoupled from the second side of the building element then even if the first side of the building element is subject to vibrations, the second side of the building element will significantly reduce the vibrations.

Another method of improving noise insulation is to install insulation in a wall or ceiling cavity. This increases the sound attenuation because some sound energy is changed to heat energy. Further, providing absorption in a cavity between building elements or between a building element and a plasterboard will provide extra mass and also lower the resonant frequency of the walls. However, insulation may lose its effectiveness at very low frequencies due to the long wavelength of sound at low frequencies. This means that bass levels such as 20-60 Hz may travel unimpeded through standard walls or ceilings.

A resonant frequency is a natural frequency of vibration determined by physical parameters of an object. This natural frequency is determined by many physical factors, mass, density, molecular structure etc. If noise vibration is applied at the resonant frequency of the object, then the level of vibration of the component is increased. One sound attenuation goal is to reduce the frequency at which the resonance occurs. Another goal is to also to ensure that there is not constructive interference whereby many components resonate at the same frequency, thereby doubling the amplitude in effect. If sound vibration strikes a plasterboard at the same frequency as it naturally resonates, it will result in higher levels of vibration and therefore increased noise.

Conduction plays a role in transmitting sound energy/vibrations through building elements and components. Sound energy will pass between components of any material that are in direct contact. Conduction also plays a large role in flanking noise, i.e. noise that travels from one room to another room by an indirect path. To reduce the conduction of a structure, mechanical breaks (like cuts) could be used or alternatively, the damping of the structure could be increased.

Figure 1 shows a side view of a clip 100 configured to be attached to a building element. The clip 100 includes a bracket 102 and a sound attenuator 104. In some examples, the bracket 102 is formed of a sheet metal, such as aluminium or galvanised steel. The main body of the bracket 102 may define a planar surface. In some examples, the clip 100 includes one or more arms or projections 106 that project from the planar surface of the sheet metal. The arms 106 may be made of a distinct component connected to the sheet metal or alternatively be a folded part that is continuous with the main body of the bracket 102. The arms 106 may include one or more slots or recesses 108 that enable a channel, such as a furring channel or bar to be held by the clip 100.

The sound attenuator 104 may abut the main body of the bracket 102 and be received in a hole (not shown) in the bracket 102. In one example, the sound attenuator 104 is made of a rubber polymer such as silicone. The dynamic characteristics of silicon rubber provide resilience and significant energy dissipation capacity, which makes the material extremely useful for controlling and absorbing vibrational energy. In use, the sound attenuator 104 is configured to abut the building element such as a ceiling element, wall element or floor element or bracket element.

Figure 2 shows a perspective view of the clip 100 shown in Figure 1. In the example shown in Figure 2, the sound attenuator 104 is comprised of at least a first element 110 and a second element 112. The first element 110 has a first acoustic attenuation property and the second element 112 has a second acoustic attenuation property, different to the first acoustic attenuation property. The first element 110 is at least partially enclosed by the second element 112. In the example shown in Figure 2, the first element 110 is substantially surrounded by the second element 112 around the sides, but the first element 110 has an exposed face. In this example, the first element 110 is received in a recess or hole in the second element 112. In the example shown in Figure 2, the first element 110 and the second element 112 have the same height, i.e. they terminate at the same distance from the bracket 102 so that the first element 110 and the second element 112 have a substantially flush open face. In this configuration, as the sound attenuator 104 abuts a building element, both the first element 110 and the second element 112 of the sound attenuator 104 will abut the building element.

Figure 3 shows an exploded view of the clip 100 shown in Figure 2. In this example, the second element 112 has a substantially square cross section with an opening 114 for receiving the first element 110. The opening 114 is shown as being substantially circular, but in practice, the opening 114 may be any shape corresponding to the shape of the first element 110 such that the first element 110 may be received in the opening 114 of the second element 112. In addition, the opening 114 may not extend through the whole depth of the second element 112, but rather, may extend only part-way through the second element 112 so as to form a recess in the second element 112 that can receive the first element 110. The second element 112 may also include one or more recesses 116 in the open face of the second element 112 that is configured to abut the building elements. The purpose of the one or more recesses 116 is to reduce the contact area of the sound attenuator 104 with the building element, which will reduce the transfer of sound vibrations via conduction.

The first element 110 is shown in Figures 2 and 3 as being substantially cylindrical in shape, but may take the form of any shape that fits in the opening 114 of the second element 112 and the hole 118 of the bracket 102. In use, the second element 112 and the first element 110 are configured to fit together via an interference or engineering fit. The second element 112 may be substantially cube shaped or cylindrical shaped.

In some examples, the first element 110 may include one or more recesses 120 in the face of the first element 110. The recesses 120 in the face of the first element 110 may form one or more concentric circles or ribs. In the example in which the face of the first element 110 and the face of the second element 112 are substantially flush and both configured to contact the building element in use, the recesses 120 on the face of the first element 110 act to reduce the contact area between the building element and the first element 110.

The first element 110 is configured to be received in an opening 118 in the bracket 102. The first element 110 can be considered to be formed of a first part or region, which is located on a first side of the bracket 102, i.e. the part of the first element 110 that abuts and is received in the second element 112, and a second part or region, which is located on the other side of the bracket 102 to the first part, i.e. the same side as the one or more arms 106. The first part and the second part of the first element 110 are shown in more detail in Figures 4A and 4B. The first element 110 may also include a through-hole 122 for receiving one or more fixtures therethrough. In use, a fixture may project through the opening 122 of the first element and through the opening 118 in the bracket 102. The fixture may also project through an opening 114 in the second element 112. In use, the fixture may be used to attach the clip 100 to the building element. The fixture may be any suitable element for fixing the clip 100 to the building element, such as a screw or a bolt.

In one example, the acoustic attenuation properties of the first element 110 and the second element 112 is based on shore hardness and the first element 110 has a hardness of between 25 to 60 A shore hardness. More preferably, the first element 110 has a hardness of between 35 to 50A shore hardness. Even more preferably, the first element 110 has a hardness of between 40 and 45 A shore hardness. In other examples, the first element has a hardness of between 60-65A shore hardness. In one example, the second element 112 has a hardness of between 35 to 70A shore hardness. More particularly, the second element 112 has a hardness of between 45 to 60 A shore hardness. Even more particularly, the second element 112 has a hardness of between 50 to 55 A shore hardness. In other examples, the second element has a hardness of between 20 to 25 A shore hardness. In some examples the first element 110 has a lower hardness compared with the second element 112. In this example, the softer, first element 110 may be the main point of contact with the building element and more vibrations will be absorbed by the first element 110 compared with the second element 112. In this example, the second element 112 acts a bumper to ensure that the bracket 102 remains substantially parallel to the building element after a weight has been applied.

In one example, the acoustic attenuation properties of the first element 110 and the second element 112 is based on densities and the first element 110 and the second element 112 have substantially different densities. For example, the first element 110 has a density of between approximately 1260kg/m ³ to 1408kg/m ³ , more preferably between 1300kg/m ³ to 1368kg/m ³ and even more preferably between 1325 kg/m ³ and 1343 kg/m ³ . The second element 112 has a density of approximately 1300kg/m ³ to 1450 kg/m ³ , more preferably between 1340 kg/m ³ and 1410 kg/m ³ and even more preferably between 1365 kg/m ³ and 1385 kg/m ³ .

The bracket 102 may also include one or more indents 124. In the example shown in Figure 3, the bracket 102 includes a first indent 124 located on a first side of the opening 118 and a second indent 124 located on a second side of the opening 118, i.e. indents 124 may be provided on either side of the opening 118. The indents 124 add strength to the bracket 102, allowing it to hold more weight without deforming. Further, branding, such as MuteClip™, may be engraved or depicted on a face of the main body of the bracket 102.

In the example shown in Figure 3, the clip 100 also includes an insert 126. In some examples, the insert 126 includes a bushing 128 and a flange 130. In use, the bushing 128 is configured to be inserted into the through hole 118 of the bracket 102 and the hole 122 of the first element 110. The bushing may also have an opening therethrough for receiving a fixture, such as a screw or a bolt, as described above.

The flange 130 of the insert 126 provides a bearing surface for a fixture configured to fix the clip 100 to a building element. The insert 126 may be formed of any resilient material, such as aluminium or galvanised steel.

In some examples, the clip 100 has a height of between 50mm and 102mm, more preferably between 64mm and 88mm and even more preferably between 74mm and 78mm. The clip 100 may have a width of between 29mm and 41mm, and more preferably between 33mm and 37mm. The depth of the clip 100 and the insert when inserted into the clip 100 may be approximately between 23mm to 35mm. More preferably, the clip 100 and insert 134 may have a depth of between 27mm and 31mm.

The clip 100 comprising a sound attenuator 104 provides a device that is resilient (or soft) enough to transmit less acoustic energy, but is still supportive enough to hold a heavy mass, such as the plasterboard. In addition to this, the clip 100 provides a form of mechanical damping within the clip 100 between the first element 110 and the second element 112 to add further performance.

The clip 100 is strong enough to hold heavy mass, such as a resilient furring channel 134 holding a plaster board. Further, the clip 100 is configured to mechanically decouple walls and ceiling linings from the supporting building elements, such as timber/metal/concrete substrate. Therefore the clip 100 provides a significantly reduced surface area of direct contact from one side of a building element to the building element lining, thereby reducing transmission levels significantly.

The clip 100 creates a void between a building element and a building element liner, such as plasterboard, to allow an absorption material, such as mineral wool, to be placed in the void, even if the clip 100 is fitted direct to a solid wall or ceiling.

The construction of the first element 110 and the second element 112 work like mini shock absorbers to dampen movement back and forth as they move over each other and deform thereby absorbing acoustic energy and turning it into heat. As the first element 110 and the second element 112 have different acoustic absorbing properties, then they may act in tandem to improve the overall acoustic absorption of the clip 100.

Figure 4 A shows a side exploded view of the clip 100. As shown in Figure 4 A, the first element 110 has a varying width across its length. The first element 110 may includes a first part 110A and a second part 110B separated by a waist 132. In use, the waist 132 is configured to fit in the through hole 118 of the bracket 102. In one example, the second part 110B of the first element is a truncated cone that, during assembly, may be pushed through the through hole 118 of the bracket 102. The second part 110B may be considered to have a chamfered end. The waist 132 may be sized to be larger than the through hole 118 of the clip 102. However, due to the flexible nature of the first element 110, the waist 132 is configured to deform so as to match the size of the through hole 118 and form an interference fit between the first element 110 and the bracket 102. In use, a second part 110B of the first element 110 is located on the opposite side of the bracket 102 to the first part 110A of the first element 110.

The first part 110A of the first element 110 may be substantially cylindrical and be configured to be received within a substantially cylindrical hole 114 of the second element 112.

In use, the flange 130 of the insert 126 is configured to abut the first element 110 and acts as a floating washer for a fixture (not shown), which spreads the force applied to the clip 100 when fixing the clip 100 to the building element. In use, a fixture (not shown) is configured to bear upon the flange 130 of the insert 126. The bushing 128 is configured to project through the second part 110B of the first element 110 and the through-hole 118 of the bracket 102.

The insert 126 aids to at least partially decouple the fixture from the bracket 102 and furring channel 134 and also guides the fixture to remain substantially perpendicular to the building element for a strong hold.

In other examples, a fixture is used that projects through the hole 118 of the bracket 102 in use, and is fixed to a building element, such as a bracket.

The insert 126 provides the clip 100 with stability and aids in holding the first element 110, the clip 100 and second element 112 together. As discussed above, the first element 1 10 and the second element 1 12 may be configured to fit together via an interference or engineering fit. In some examples, the first element 110 comprises a lip/under-hang that has a corresponding shape to an overhang of the second element 112 to enable the second element 112 to be received on the first element 110 and prevent the first element 110 and the second element 112 from separating. In some examples, the first element 110 and the second element 112 are modular such that a user may be able to easily switch between elements having different acoustic attenuation properties. This enables a custom and tailored acoustic solution to be provided by the clip 100 allowing for future developments and customised acoustic solutions.

In some examples, the acoustic attenuation property is based on one or more of density, elasticity, hardness, stiffness and Young’s Modulus. For example, the first element 110 may have a Young’s Modulus value of between approximately 1.345N/mm ² and 1.520 N/mm ² , preferably between 1.41N/mm ² and 1.455 N/mm ² and the second element may have a Young’s Modulus of between 1.707 N/mm ² and 1.920 N/mm ² and 1.772N/mm ² and 1.855 N/mm ² . In other examples, the first element 110 may have a stiffness value of between 0.20 kN/mm and 0.30 kN/mm and the second element may have a stiffness value of between 0.30 kN/mm and 0.40 kN/mm. In other examples, the first element 110 may have an elasticity limit of between 2.4MPa and 4.4MPa and the second element may have a elasticity limit of between 3.4MPa and 5.5MPa.

For example, one or more of the hardness, density, elasticity, stiffness and/or Young’s Modulus of the first element 110 and one or more of the hardness, density, elasticity, stiffness and/or Young’s Modulus of the second element 112 may be selected so as to reduce the mass required to achieve a specific dB reduction with airborne/impact sound or it can support high mass for highest possible sound attenuation overall. The clip 100 effectively improves sound reduction in all frequencies, but is particularly effective and attenuating sounds with frequencies of 100Hz and above. The stiffness may relate to either static or dynamic stiffness. Further, the insert 126 and the bracket 102 may also be modular, which means that the components of the clip 100 may be easily assembled and disassembled to allow a user to make future system modifications and upgrades such as changes to element density, hardness, elasticity, Young’s Modulus and/or stiffness. There is no (or very little) adhesive used in the production of the clip 100 because it is held together by an engineered friction fitting. In some examples due to the design and closely engineered tolerances, no adhesive is used in the clip 100. This also means that each component may be able to be returned after use, or be re-used or disassembled and recycled.

The bushing 128 of the insert 126 may be sized so as to be slightly bigger than the opening 122 of the first element, such that as the insert 126 is received in the opening 122 of first element 110, the first element 110 is pressed further against the second element 112 to increase the stability of the clip 100. The engineering fit between the first element 110 and the second element 112 results in less adhesive being required to attach the first element 110 and the second element 112 together. In some examples, adhesive is not required at all.

Figure 4B shows a side view of an example of the sound attenuator 104 comprising the second element 112 and the first element 110 received within the second element 112.

Figure 5 A shows an example of two clips 100 located on a building element in the form of a brick wall. For clarity, the fixtures are not shown in the example of Figure 5 A, but in practice a fixture would be used to attach each of the clips 100 to the wall. Whilst two clips 100 are shown in this example, more or fewer clips 100 may be used in practice. Figure 5B shows the two clips of Figure 5 A with a furring channel 134 or furring bar inserted and held by the two clips. The channel 134 is configured to be received and held by the clip 100 as shown in Figure 6. In one example, the furring channel 134 is received in one or more slots or recesses 108 defined in the one or more retaining arms 106 of the clip 100. An example of a furring channel 134 is shown in more detail in Figure 6 A. The furring channel 134 may be formed from bent sheet metal so as to create a two- tiered profile. Two ends 136 of the furring channel 134 may form a first tier and a middle section 138 may form a second tier 140, which is in a different plane compared with the first tier. In use, the two ends 136 of the furring channel 134 are configured to be received in the slots 108 of the bracket 102. The shape and material of the furring channel 134 enables some flexibility or movement in the furring channel 134 such that the furring channel 134 may be elastically deformed to enable the two ends 136 to be moved closer together to fit into the recesses or slots 108 of the bracket 102. Once the force has been removed from the furring channel 134, the furring channel 134 will return to the original shape and be resiliently held by the clip 100. The middle section 138 of the furring channel 134 will be projected from the clip 100 and provide a flat surface on which a second layer (or additional layer) of building material may be added, such as a plasterboard. The two ends 136 of the furring channel 134 may include at least two indentations 139 in the middle part 138 of the channel to allow the channel 134 to hold more weight. Further, in some examples, the two ends 136 comprise two layers of folded sheet metal so as to provide an increased depth of the ends 136 of the furring channel 134. The increased depth means that the channel 134 may be held more securely by the clip 100.

Figure 6B shows a perspective view of part of the furring channel of Figure

6A.

Figure 7A shows a side view of an example of the furring channel 134 received in the slots or recesses 108 of the retaining arms 106 of the clip 100. As shown in Figure 7A, the retaining arms 106 may be substantially perpendicular to the main body of the bracket 102. As described above, the furring channel 134 may need to be temporality elastically deformed such that the two ends 136 are moved closer together to allow them to fit within the slots or recesses 108 of the retaining arms 106. When the deforming force is removed, the furring channel 134 will return to the original position so that it is held by the clip 100. Figure 7B shows a side view an example of the furring channel 134 received in the slots or recesses 108 of the retaining arms 106 of the clip 100 and the clip 100 is attached to a building element 141 via a fixture 142. For conciseness, reference signs of Figure 7A have not been repeated in Figure 7B.

In the example of figure 7B, the fixture 142 is a screw received through the insert 126, the first element 110, the through hole 118 of the bracket 102 and the second element 112. A plasterboard 143, such as a 15mm acoustic plasterboard, is shown as being attached via a second fixture 145. In this example, a void is created between the building element 141 and the plasterboard 143 (i.e. in the region with the clip 100), which helps to increase sound insulation between the building element 141 and the plasterboard 143. Figure 7B shows an example of the system, including the clip 100, the fixture 142 and the furring channel 134. In some examples, in addition to the clip 100, an absorption material may be placed in this void. In some examples the absorption material is an acoustic mineral wool.

As can be seen in Figure 7B, at least part of the sound attenuator 104 abuts the building element 141 in use. In some examples, only the second element 112 of the sound attenuator abuts the building element, but in other examples, both the first element 110 and the second element 112 will abut the building element 141 is use.

A second example of a clip 200 is shown in Figure 8A and 8B. In this example, the clip 200 includes a bracket 202 and an insert 226, which may be identical to the bracket 102 and insert 126 shown in the example of the clip 100 shown in Figure 1 to 4. In this example, the sound attenuator 204 includes a second element 212 that substantially surrounds all of the first element 210. In this example, the second element 212 is substantially located between the first element 210 and the building element and abuts both the first element 210 and the building element.

The second element 212 may include one or more ribs and/or recesses to reduce the contact surface area between the second element 212 and the building element and hence reduce the amount of conduction. An exploded view of the second example of the clip 200 is shown in Figure 8B. As described previously, the insert 226 and the bracket 202 are substantially similar to the insert 126 and the bracket 102 described in relation to Figures 1 to 4, but may have a different length. The first element 210 comprises a first part 211, which in use is configured to be received in a recess in the second element 212. In some examples, the first part 211 of the first element includes one or more bumpers configured to be received in slots within the second element 212. The bumpers may include one or more nipples 215 that project from the surface of the bumpers. The first element 210 also includes a second part 213 may be substantially in the shape of a truncated cone. The second part 213 may be inserted into the through hole 218 in the bracket 202. The first part 211 and the second part 213 may be separated by a waist (not shown), which is dimensioned to be a snug fit within the through hole 218 of the bracket 202. The first element 210 and the second element 212 both include openings so as to receive at least part of the insert 226 in use. The first element 210 may include a lip around the perimeter of the first element 210 that corresponds to an outer lip of the second element 212 to enable the first element 210 and the second element 212 to fit together. In use, the second element 212 is configured to abut the building element and the nipples 215 of the first element may also abut the building element.

As with the first example of the clip 100, an acoustic attenuation property of the first element 210 is different to acoustic attenuation property of the second element 212. In some examples, the first element 210 has a lower hardness value compared with the second element 212. However, in other examples, the second element 212 may have a lower hardness value compared with the first element 210. Further, as with the first example of the clip 100, in one example, the first element 210 and the second element 212 have substantially different densities. For example, the first element 210 has a density of approximately 1260kg/m ³ to 1408kg/m ³ , more preferably between 1300kg/m ³ to 1368kg/m ³ and even more preferably between 1325 kg/m ³ and 1343 kg/m ³ . The second element 212 has a density of approximately 1300kg/m ³ to 1450 kg/m ³ , more preferably between 1340 kg/m ³ and 1410 kg/m ³ and even more preferably between 1365 kg/m ³ and 1385 kg/m ³ . In some examples, the second element 212 has a lower density compared with the first element 210, but in other examples, the first element 210 has a lower density compared with the second element 212.

The use of the clip 100, 200 improves the sound insulation in a building in numerous ways. Firstly, the clip 100, 200 increases the amount of mass that may be attached to the building element, such as a wall element or a ceiling element because the physical design of the clip 100 with the sound attenuator 104, which may act as a bumper makes the clip 100 remain substantially parallel to the building element even with more weight added to the clip 100. Also the geometry of the bracket 104 reduces the lever distance from the mass to the pivot point. As the mass that may be attached to the building element increases, then more noise energy is required to pass from one side of the building element to the other, as described above.

Secondly, the use of a first element 110, 210 having a first acoustic attenuation property and a second element 112, 212 having a second acoustic attenuation property, different to the first acoustic attenuation property, provides a layer of sound de-coupling because the first element 110, 210 and the second element 112, 212 may have different resonant frequencies due to the different acoustic attenuation property values. The first element 110, 210 and the second element 112, 212 may have different physical properties compared to each other, which may also affect the resonant frequencies. For example, the first element 110, 210 may have a different mass or surface area compared with the second element 112, 212.

As such, even if sound travelling through the building element matches, or is close to a resonant frequency of one of the first element 110, 210 or second element 112, 212 it will not match or be close to the resonant frequency of the other of the first element 110, 210 or the second element 112, 212. Using a clip with a sound attenuator 104, 204 comprising plurality of elements having different acoustic attenuation property values, such as hardness and/or density therefore improves the sound insulation of a building. Further, the use of the clip 100 creates a void between a building element and a second layer or component of the building, such as a layer of plasterboard, because the clip 100 may hold a furring channel 134 as shown in Figures 5B, 6 and 7. The presence of a void enables a sound insulating material, such as mineral wool, to be inserted in the void in between the building element and the second layer, which is created by the presence of the clip 100 and furring channel 134.

In addition, the use of the dual acoustic attenuation properties of the sound attenuator 104, 204 increases the mechanical damping in the system because the sound attenuator 104, 204 is flexible and will absorb some vibrations on the building element. In view of these features, the clip 100, 200 provides a superior sound reduction system by decoupling a wider range of structure borne and airborne frequency vibrations and therefore the clip 100, 200 increases sound attenuation overall. The sound attenuator 104, 204 may also include a fire retardant material additive in accordance with UL94 vO Flammability standard, so that the clip 100 may also include fire retardant properties.

In a third embodiment, the sound attenuator 104, 204 also includes a third element located between the first element 110, 210 and the second element 112, 212. In this example, the first element 110, 210, the second element 112, 212 and the third element each has a different acoustic attenuation property value. By providing a third element in between the first element and the second element, the clip 100, 200 provides an extra layer of mechanical isolation in the building. Further, as the third element has an acoustic attenuation property different to the acoustic attenuation property of the first element 110, 210 and the second element 112, 212 the third element will have a different resonant frequency compared with the resonant frequencies of the first 110, 210 and second elements 210, 212. As such, there is an extra layer of frequency isolation because even if a sound vibration has a frequency that is close to a resonant frequency of one or more of the first element 110, 210, second element 112, 212 and third element, then it will not have a frequency close to the resonant frequency of one or more others of the first element 110, 210, second element 112, 212 and third element. In use, a sound attenuator comprising a plurality of elements having different hardness, densities, elasticities, Young’s Modulus values and/or stiffness may be used. In one example, the sound attenuator 104, 204 may include a fourth element having a different acoustic attenuation property compared with the first, second and third elements.

A third example of a clip 300 is shown in Figure 9A and 9B. In this example, the clip 300 includes a bracket 302 and an insert 326, which may be identical to the brackets 102, 202 and inserts 126, 226 of the example of the clips 100 and 200 shown in Figures 1 to 8. In this example, the sound attenuator 304 includes a second element 312 that is substantially cylindrical and substantially surrounds the entire first element 310 such that, in use, only the second element 312 is configured to abut the building element. In this example, the second element 312 is substantially located between the first element 310 and the building element and abuts both the first element 310 and the building element.

In this example, the first element 310 is not configured to abut the building element in use. The second element 312 may include one or more ribs and/or recesses to reduce the contact surface area between the second element 312 and the building element and hence reduce the amount of conduction.

An exploded view of the third example of the clip 300 is shown in Figure 9B. As described previously, the insert 326 and the bracket 302 are substantially similar to the inserts 126, 226 and the brackets 102, 202 described in relation to Figures 1 to 8, but may have a different length. The first element 310 comprises a first part 311, which in use is configured to be received in a recess in the second element 312. The first element 310 also includes a second part 313 may be substantially in the shape of a truncated cone. The second part 313 may be inserted into the through hole 318 in the bracket 302. The first part 311 and the second part 313 may be separated by a waist (not shown), which is dimensioned to be a snug fit within the through hole 318 of the bracket 302. The first element 310 and the second element 312 both include openings so as to receive at least part of the insert 330 in use. The first element 310 may include a lip around the perimeter of the first element 310 that corresponds to an outer lip of the second element 312 to enable the first element 310 and the second element 312 to fit together.

As with the first example of the clips 100, 200 the acoustic attenuation property of the first element 310 is different to the acoustic attenuation property of the second element 312. In some examples, the first element 310 has a lower hardness value compared with the second element. Further, as with the first and second examples of the clips 100, 200 in one example, the first element 310 and the second element 312 have substantially different densities. The first element 310 may have a different elasticity, stiffness or Young’s Modulus value compared with the second element 312.

Figure 10 shows an example of the clip 100 attached to a building element, which in this example is a ceiling steel anchor 140. In this example, a fixture is in the form of a bolt 142, which abuts the insert 126 of the clip 100. The second part of the first element 110 is shown between the bracket 102 and the flange 130 of the insert 126. In this example, the flange 130 of the insert acts as a washer for the fixture and spreads the load from the fixture to the first element 110. In this example, the bolt may have a nut engaged with the bolt so as to hold the anchor 140 to the clip 100. As can be seen in Figure 10, the second element 112 abuts the building element in the form of an anchor 140.

In use, a system includes the clip 100, 200 in addition to a furring channel or bar (not shown) and fixture.

The clip 200 has been tested in a UKAS accredited independent acoustic testing laboratory and the results provided below. In this example, the clip 200 shown in Figure 8 A comprising a sound attenuator 204 including first element 210 and a second element 212, wherein the second element 212 has a different acoustic attenuation property compared with the first element 210 was compared against a clip having a sound attenuator of similar geometry, but with only a single element having a single acoustic attenuation property. The acoustic testing laboratory included a source room and a receiving room separated by a building element and plasterboard. The source room has a volume of approximately 136m ³ and the receiving room has a volume of approximately 220m ³ .

A timber-frame was built in a 3600mmx2400mm aperture in a transmission suite. The timber measured 95mm x 45mm in cross section and was lined with a self- adhesive profiled rubber strip to decouple the timber frame from the aperture. The timber was used to build a frame around an internal periphery of the aperture and a timber, without lining, was used to form studs that were screwed to the peripheral frame at 600mm centres. The join between the frame and the brick aperture was sealed on the receiver room side and noggins of the same timber were installed between the studs at 1200mm from the base. Therefore, in this test, the building element was a timber frame. A layer of plasterboard having a mass of approximately 12.5kg/m ³ and a thickness of 15.1mm was screwed to a receiver room side of the frame. The boards were raised off the aperture base while being fixed in place. Mesh tape was used to cover the joins between boards and the same sealant was used to fill the joins. In the first example, a clip having a sound attenuator made of only a single element was used. A plurality of clips were attached to the timber frame at 600mm spacings using fixtures. A furring channel was attached to the clip and the plasterboard was secured to the furring channel.

The test procedure adopted follows that detailed in BS EN ISO 10140: Part 2: 2010 “Acoustics - Laboratory measurements of sound insulation of building elements; Part 2: Measurement of airborne sound insulation”

The measurements were performed in the large transmission suits of the University of Salford. The suite comprises two structurally isolated reverberant rooms with a test opening between them in which the test specimen in inserted.

The test involves producing a known sound field in the source room and measuring the resultant sound level difference between the source room and the receiving room with the specimen installed in the test aperture. This level difference is then corrected so as to take into account the equivalent absorption area of the receiving room.

The Sound Reduction Index, R (dB), is defined in BS EN ISO 10140 - Part 2: 2010 as R = Li - L ₂ + 10 logio(S/A) where:

Li is the average sound pressure level in the source room (dB)

L 2 is the average sound pressure level in the receiving room (dB)

S is the area of the test specimen (m ² )

A is the equivalent absorption area of the receiving room (m ² )

The generation of sound field in the source room is described below. Wide band, random noise from the generator in the real time analyser was amplified and reproduced in the source room using alternately one of three fixed loudspeaker systems, (La, Lb and Lc). Omni-directional loudspeakers were used. The output of the generator was set with the intention that the sound pressure level in the receiving room was at least 15 dB higher than the background level in any frequency band. The loudspeakers were positioned in the comers of the room and at such a distance from the test specimen that the direct radiation upon it was not dominant.

The sound pressure levels were measured using one-third octave band filters. Measurements covered all the one-third octave bands having centre frequencies in the range from 50Hz to 5000Hz.

Sound pressure levels were measured simultaneously in the source and receiving rooms using loudspeaker La as the sound source. Measurements were recorded at 6 fixed microphone positions in each room, using an averaging time of 16s and the average level in each room was calculated on an energy basis in each one-third octave frequency band. The procedure was then repeated with loudspeakers Lb and Lc as the sound source. The overall average level difference in each frequency band was then calculated as the arithmetic average of the two sets of results. For each set of microphone/loudspeaker positions, the distances separating microphones from other microphones, room boundaries and diffusers, were greater than 0.7m and the distances separating microphones from the sound source and the test specimen were greater than 1 0m.

The correction term, A, in the above equation was evaluated from the reverberation time and calculated using Sabine’s formula:

A=0.16V/T where:

V is the volume of the receiving room (m ³ )

T is the reverberation time (s).

The reverberation time of the receiving room was measured using a decay technique. The decays were produced be exciting the toom with wide band random noise and stopping the excitation once the room became saturated. The resulting decaying sound field was monitored at 6 fixed microphone positions using a one-third octave band real time analyser. The sound spectrum was sampled at 32 millisecond intervals and stored in memory. Five decays were measured at each microphone position and averaged. The time taken for the sound to decay by a given amount was measured and then extrapolated to determine the reverberation time. The measurements were repeated using an alternative sound source. The results from each set of positions were averaged (i.e. 60 reverberation decays at each frequency).

Figure 11 shows the test results of the first experiment in which a clip having a sound attenuator made of only a single element was used. A plurality of clips were attached to the timber frame at 600mm spacings using fixtures. A furring channel was attached to the clip and the plasterboard was secured to the furring channel. Figure 11 relates to a laboratory measurement of sound insulation of building elements under BS EN ISO 10140-2 : 2010, Sound Reduction Index. The test had the following conditions:

Description: plasterboard partition

Sample size: 8.64 m ² Source Room Volume: 136 m ³

Source Room Temperature: 22.3 °C

Source Room Relative Humidity: 33.3%

Receiving Room Volume: 221 m ³

Receiving Room Temperature: 20.8 °C

Receiving Room Relative Humidity: 43.7%

Ambient Pressure: 99.5 kPa

Measured Mass Per Unit Area: 25.4 kg/m ²

Curing Time: Not applicable

Line A represents“R” and Line B represents the shifted reference curve : ISO 717-1 [100Hz - 3150 Hz]

The results of R (Line A) is shown in the following table:

In figure 11, the“Y-axis” of the graph in represents the“Sound Reduction Index [dB]” and the“X-axis” represents frequency [Hz] The test of figure 11 produced the following ratings according to BS EN ISO 717-1 :

Rw (C; Ctr) = 53 (-5 ; -13) dB

C50-3150 = -8dB

Ctr, 50-3150 = -21dB

C _50-5000 = -8dB

Ctr, 50-5000 = -21dB

Cioo-5000 = -4dB

Ctr, 100-5000 = -13dB The Evaluation is based on laboratory measurement results obtaining in one-third- octave bands by an engineering method.

Figure 12 shows the test results of a second experiment, in which the clip 200 shown in Figure 8 comprising a sound attenuator including first element 210 and a second element 212, wherein the second element 212 has a different acoustic absorption property compared with the first element 210 was used. The first element 210 used in the test has a shore hardness of between 40-45A a Young’s Modulus of between 1350 and 1519 N/mm ² , a density of approximately 1334kg/m ³ and a mass of 8.1g. The second element 312 has a shore hardness of between 50-55 A a Young’s Modulus of between 1.707 and 1.920 N/mm ² , a density of approximately 1374kg/m ³ and a mass of approximately 12g. Figure 12 relates to a laboratory measurement of sound insulation of building elements under BS EN ISO 10140-2 : 2010, Sound Reduction Index. The test had the following conditions:

Description: plasterboard partition

Sample size: 8.64 m ²

Source Room Volume: 136 m ³

Source Room Temperature: 21.7 °C

Source Room Relative Humidity: 32.4%

Receiving Room Volume: 221 m ³

Receiving Room Temperature: 20.7 °C

Receiving Room Relative Humidity: 43.1%

Ambient Pressure: 99.4 kPa

Measured Mass Per Unit Area: 25.4 kg/m ²

Curing Time: Not applicable

Line A represents“R” and Line B represents the shifted reference curve : ISO 717-1 [100Hz - 3150 Hz]

The results of R (Line A) is shown in the following table:

In figure 12, the“Y-axis” of the graph in represents the“Sound Reduction Index [dB]” and the“X-axis” represents frequency [Hz] The test of figure 12 produced the following ratings according to BS EN ISO 717-1 :

Rw (C; Ctr) = 54 (-4 ; -l l) dB

C50-3150 = -8dB

Ctr, 50-3150 = -21dB

C50-5000 = -8dB

Ctr, 50-5000 = -21dB

Cioo-5000 = -3dB

Ctr, 100-5000 = - 11 dB The Evaluation is based on laboratory measurement results obtaining in one-third- octave bands by an engineering method.

As can be seen in Figures 11 and 12, the sound reduction index (dB) curve is higher in the test results of Figure 12, in which the clip 200 having a first element 210 and a second element 212 is used compared with the clip only having a single element, the results of which are shown in Figure 11.

A comparison of the results for Rw (weighted sound reduction index, Lab measurement) and Rw+Ctr (weighted sound reduction index, Lab measurement + Road traffic Noise) as defined by BS ISO 717-1 :2013“Acoustics— Rating of sound insulation in buildings and of building elements - Part 1 : Airborne sound insulation” is shown in Figure 13. As shown in Figure 12, the clip 200 has a Rw value of - 54dB, whereas the clip comprising a sound attenuator only having a single element has an Rw value of - 53dB, so the clip 200 comprising a first element 210 and a second element performs ldB better for Rw. In relation to the Rw+Ctr, the clip 200 has a Rw+Ctr value of -43dB, whereas the clip comprising a sound attenuator only having a single element has an Rw+Ctr value of - 40dB, so the clip 200 comprising a first element 210 and a second element 212 performs 3dB better for Rw+Ctr. Therefore, the clip 200 provides an improved sound reduction over existing clips.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, [add possibilities]. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.