Combination sound-deadening board

Details Combination sound-deadening board Combination sound-deadening board

2001-10-16

2004-07-06

Lockett, Kimberly (Department: 2837)

Acoustics

Sound-modifying means

Sound absorbing panels

C181S286000, C181S290000, C052S144000

Reexamination Certificate

active

06758305

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to building materials and more particularly to materials used for sound insulation.
In building modern structures, such as single-family houses or commercial buildings, an important factor to consider is noise control. In order to provide a quiet environment, sounds originating from sources such as televisions or conversation must be controlled and reduced to comfortable sound pressure levels. To achieve such an environment, builders and designers must address a multitude of factors, among them the construction and composition of building component assemblies that separate rooms from other rooms or from the outside environment. Such assemblies may, for example, take form as interior walls, exterior walls, ceilings, or floors of a building.
The term “transmission loss”: is expressed in decibels (dB) and refers to the ratio of the sound energy striking an assembly to the sound energy transmitted through the assembly. A high transmission loss indicates that very little sound energy (relative to the striking sound energy) is being transmitted through an assembly. However, transmission loss varies depending on the frequency of the striking sound energy, i.e., low frequency sounds generally result in lesser transmission loss than high frequency sounds. In order to measure and compare the sound performances of different materials and assemblies (i.e., their abilities to block or absorb sound energy), while also taking into account the varying transmission losses associated with different sound frequencies, builders and designers typically use a single-number rating called Sound Transmission Class (STC), as described by the American Society For Testing and Materials (ASTM). This rating is calculated by measuring, in decibels, the transmission loss at several frequencies under controlled test conditions and then calculating the single-number rating from a prescribed method. When an actual constructed system is concerned (i.e., where conditions such as absorption and interior volume are not controlled in a laboratory environment), the single-number rating describing the acoustical performance of such a system can be expressed as a field STC rating (FSTC), which approximates a STC rating when tested on-site. The higher the FSTC rating of a constructed system, the greater the transmission loss.
A conventional wall assembly
300
(called a wood stud wall) is shown in FIG.
3
and consists of two gypsum boards
303
(also referred to as drywall or sheetrock skins) attached directly to either sides of wood studs
301
. The space between the wood studs
301
may be filled with some type of fibrous insulation
305
(e.g., fiber glass batts). A wall assembly such as assembly
300
generally results in transmission loss values between STC
30
and STC
36
, because although the cavity area between the wood studs
301
is filled with sound insulation material
305
, sound energy can easily pass through the structural connections between the wood studs
301
and the gypsum boards
303
. Accordingly, assembly
300
is generally ineffective in reducing sound energy transmission.
Several methods are currently used by builders to produce wall and ceiling/floor assemblies with higher FSTC ratings than the performance of a basic wood stud configuration. One such method is the use of resilient channels in a wall assembly
400
, shown in
FIG. 4
a
. This method involves inserting one or more thin metal channels
407
between one of the drywall skins
403
and framing members
401
. The resilient channels
407
act as shock absorbers, structural breaks, and leaf springs, reducing the transmission of vibrations between a drywall skin
403
and the framing members
401
. However, the resilient channel technique is difficult to install correctly and requires excessive labor costs. It is very easy to “short out” a resilient channel
407
by improper nailing techniques (e.g., screwing long screws into the wood studs
401
behind the resilient channel
407
). When this occurs, the sound isolation of wall assembly
400
remains unimproved. Similarly, problems relating to the difficulty of installing resilient channels may result when the technique is used to sound-isolate floor-ceiling assemblies.
The use of resilient channels also increases the overall thickness of a wall or floor-ceiling assembly by at least ½ inch. This increase may prevent a builder or designer from using standard components that typically interface with a wall or floor-ceiling assembly. An example of such a component may be a doorjamb, where the increase in a wall assembly may necessitate the use of an expensive, non-standard size door jamb.
Other current practices involve staggering the positions of wall studs
401
(as illustrated in
FIG. 4
b
) or using double stud construction (as illustrated in
FIG. 4
c
). These methods create a larger cavity depth and can reduce the structural connections between wall assembly components
401
and
403
, thereby allowing an assembly
400
to achieve relatively high FSTC ratings. However, both of these methods double the cost of framing and increase the thickness of wall assembly
400
by approximately two to four inches, which increases installation and material costs as described above.
In addition, various sound absorbing or barrier materials are currently used to provide a structural break between wall studs or floor-ceiling joists and the boards attached to them. Examples of such materials include GyProc® by Georgia-Pacific Gypsum Corporation and 440 Sound-A-Sote™ by Homasote and Temple-Inland SoundChoice™. While capable of providing additional sound-transmission loss, these materials are generally dense and heavy, resulting in high handling and installation costs.
Accordingly, what is needed is a low-cost material between the framing members and building boards either in sheets or strips that can be installed in wall or floor-ceiling assemblies to provide additional substantial acoustical performance, while requiring less installation steps than current practices and allowing the use of standard size components to interface with the assemblies.
SUMMARY OF THE INVENTION
The present invention is directed to a combination sound-deadening board that is economical and provides relatively high acoustical performance improvement.
According to a first embodiment of the present invention, a combination sound-deadening board is provided, comprising a layer of structural skin, and a layer of sound-deadening material, wherein the material has an equivalent Young's Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch (psi) and a thickness between ¼ and 1 inch, and is attached to the layer of structural skin to form a single laminate structure. This Young's Modulus may be achieved through means of basic material properties (true Young's Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.
According to a second embodiment of the present invention, a building component assembly is provided, comprising at least one assembly framing member, and at least one combination sound-deadening board that is a single laminate structure comprising a structural skin layer attached to a sound-deadening material, wherein the sound-deadening material has an equivalent Young's Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between ¼ and 1 inch, and that at least one combination sound-deadening board is attached to the assembly framing member such that the sound-deadening material faces the assembly framing member. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.


REFERENCES:
patent: 3828504 (1974-08-01), Egerborg et al.
patent: 4346782 (1982-08-01), Bohm
patent: 4705139 (1987-11-01), Gahlau et al.
patent: 5088576 (1992-02-01), Potthoff et al.
patent: 5304415 (1994-04-

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