SOUND INSULATING MATERIALS PRESENTED BY : TANDEL RAJAT B. ( ) GUIDED BY:- PROF.N.B.KAGRA GOVERNMENT ENGINEERING COLLEGE, DAHOD CIVIL ENGINEERING DEPARTMENT ACTIVE LEARNING ASSIGNMENT BUILDING CONSTRUCTON ( )

S OUND I NSULATION Sound Insulation is the measure by which the transmission of sound/noise from inside to outside or vice-versa or from one room to the other is prevented. It has different function than sound absorption. The function of a sound absorption material is to absorb and thus reduce the sound reflected from a surface, while the function of sound insulating materials construction is to reduce sound passing through it. Sound absorbers, mostly of porous materials, are poor sound insulating, while hard materials used for sound insulation are poor absorbers

General considerations in sound insulation ; The following general considerations should be made for sound insulation in buildings : The first and foremost way of insulating against air-borne noise is to isolate it at source. Air tight casements and rooms for machinery would achieve this purpose to some extent. The residential buildings should be properly located in a quiet area away from the noisy surroundings. The building should be properly oriented with respect to road the doors and windows should not face the source of noise. The different units (i.e. rooms) of a building should be properly planned so as to reduce the noise to a minimum.

The control of impact sound to some extent is possible by either providing resilient materials like carpet, linoleum, cork under layers, etc. or carries the whole surface or resilient materials, like a floating floor. The structure borne noises can be prevented by introducing discontinuities in the path of vibrating waves and by using sound absorbing materials. The construction of expansion joints in large frame structures acts in this manner. The personal protective devices, such as ear plugs, head, phones etc. can be used to reduce the noise to the extent of 20 to 30 dB. The transmission of noise by vibrations can be prevented by making the walls, floors, partitions very rigid and massive or heavy.

Sound Insulating Materials : Sound insulating materials can be broadly classified into three groups : Non-porous rigid materials Porous rigid materials Non rigid (flexible) porous materials Non-porous rigid materials : The sound insulation of non-porous, homogeneous, rigid constructions, such as plastered solid brick masonry walls varies as the logarithms of the weight per unit area. The relation between the weight of a rigid partition and its sound insulation is approximately such that every time the weight is doubled there is increase in sound insulation of about 4 to 5 dB.

Porous rigid materials : Porous rigid materials like porous concrete masonry, cinder concrete, etc. because of their sound absorptive properties which provide about 10 percent higher insulation than the non-porous materials of the same weight. In order to secure the best insulation from the porous materials, it is recommended that porous partitions should be plastered at least on one side and possible on both sides.

Non-rigid (Flexible) porous materials : These consists of felt, mineral wool, and quilt etc. They by themselves provide low sound insulation as compared to rigid materials and therefore they are not generally used for the purpose of noise reduction and isolation. However, a composite construction employing a combination of rigid materials and porous absorbers may adopted where weight is important factor.

R EFERENCES 1) Prof. DR.B.C.PUNMIA “building construction” laxmi Publication, Vol. 28, PP. 553– on&espv=2&tbm