Acoustic Solutions


Acoustic Solutions

Sound Insulation


Sound Insulation Performance: (Acoustics)


Sound Insulation:

Sound insulation refers to the ability of a material or partition / ceiling system to stop or reduce airborne sound.


Internal Sound Insulation:

Internal sound insulation is important when designing a partition wall, to stop noise passing through from an adjoining room


External Sound Insulation:

External sound insulation refers to the ability of materials to reduce sound transferring into or from a building. Good external sound insulation is important when designing and constructing external elements of a building. This includes walls, windows, doors, ventilation and roofing.


Sound Absorption:

Sound absorption is the ability of a material to absorb sound within a room.



Flanking is the transfer of noise through paths around a building element, rather than through the element itself. Flanking describes the transfer of noise through, gaps, cracks in the building element, incorrectly sealed junctions between elements

Description of common terms used when describing sound insulation performance (dB)     

The decibel (dB) is the unit used for sound level measurement. Variations of (dB) are used for different types of noise measurement. The most commonly used variation is the (dBA)


In domestic buildings, acoustic factors are not as critical. Most of the necessary sound absorption will be provided by the furnishings and fittings. Some improvements in acoustics may be required in home theatres, in which case Lafarge Gypsum's Pregybel® can be used to enhance the acoustic absorption.

In certain commercial applications such as auditoriums, the design challenges are more complex, and acoustic ceilings and walls made of Lafarge Gypsum's Pregybel® Acoustic Ceiling Board should be considered including positioning of bulkheads. The Division's acoustic specialists are available to offer assistance.

Despite the complexity of acoustic science, some basic principles are universal:
· Provide direct sound paths between sound sources and listeners - consider raking floors and try to avoid columns

· Beware of curved surfaces - convex shapes scatter sound and concave shapes focus it, often with disastrous results.

· Optimum reverberation times will depend on the use of the space and will be longer for music than for speech. With unwanted sounds, for example the noise of machinery, it is best to shorten the reverberation time as much as possible 



Unit of sound level in weighted decibels. The human ear is not equally sensitive to all frequencies of sound. The A weighting approximates the sensitivity of the ear by filtering these frequencies. A (dBA) measurement is considered representative of average human hearing.

Structures have variable sound insulation values depending on the frequency of the sound. With Lafarge Gypsum's partitions, significant improvements can be made, particularly for insulating against higher frequencies.

Insulation performance.

Effects of different walls on sound insulation perfomance


Rw Rw + Ctr Effect of different values of Rw and Rw + Ctr
25 22 Normal speech can be heard
30 25 Loud speech can be heard
35 28 Loud speech can be heard but not understood
42 35 Loud speech heard as a murmur
45 38 Must strain to hear loud speech
48 40 Loud speech can barley be heard
53 44 Loud speech cannot be heard
63 55 Music heard faintly, bass notes 'thump'
70 60 Loud music still heard faintly