Acoustics and Sound Insulation Methods

Acoustics and bottom Insulation MethodsAcoustics and penetrate InsulationABSTRACTAcoustics is the study of lead. The knowledge of this field is infallible as it helps in creating peaceful surroundings. The technical knowhow of good for you(p) disengagement has been helpful in constructing cash in ones chipsal theatres, hospitals, Auditoriums, fixture pads, and so forthtera Sound is created when a resurrect vibrates. When this quivering is periodic or rhythmic then the hygienic produced is amiable to the ears eg. Musical Notes. On the contrary when the vibration is non-periodic and irregular then it is termed as noise. eg. Infants crying.INTRODUCTIONSound travelings in the form of longitudinal waves. Each wave moves backward and forward passing on the vibration to the next. For us to be able to hear just clearly it is very important for the waves to travel uninterrupted. It is be that go away travels the fastest in solids, then in liquids and the least in line of bus iness. This is because in solid the molecules atomic number 18 so tightly packed that the transmission is the easiest. In liquids too the molecules are fairly close to individually other where as in air it hold ups a little tough for sound to travel. Sound cannot travel in vacuum as it needs a medium to travel. The speed of sound in air depends upon the moisture or dryness in air. The more the moisture the faster sound will travel.CHARACTERISTICS OF break downIntensity and Loudness of soundLoudness is the response of gentlemans gentlemans to the impact of sound. Whereas intensity is the amount of sound waves passing finished per unit area per unit time.Frequency and PitchSounds can be of several(predicate) types and wavelengths. Pitch isWhat helps us distinguish between sounds of same loudness but of different frequencies. This is thecharacteristic which helps us recognise a mans voice andwomens Voice.QualityThe quality of sound is what enables us to differentiate between tw o musical tones played on different instruments. A study has shown that the notes produced by instruments are at times pure notes. They have nigh fundamental tones of frequency fo and excess tones of frequency 2fo, 4fo, etc. called over tones. The fundamental is heard very clearly because it has greater impact human ear.TABLE 1.1, ACCEPTABLE NOISE LEVELTYPE OF BUILDINGNOISE LEVEL RANGE ( decibels, db)1. tuner and T.V. studio25-302. Music Room30-353. Hospitals and auditoriums35-404. Apartments, hotels and homes35-405. Conference populate and libraries35-406. Class rooms40-457. Banks and stores45-508. Restaurants50-552REFLECTION OF beneficialSound waves from a plain surface reflect in the same way as that of light. The saint of incidence is equal to the angel of reflection.Following are the characteristics of reflection of soundWhen sound waves reflect from a flat surface the wave fronts form a spherical shape and the centre of curvature is the quotation of soundWhen sound waves reflect from a convex surface they get magnified and therefore become trim downner and weaker. Convex surfaces can be employ in interior spaces to reduce the impact of sound.Sound waves that reflect from a concave surface are very dense and compressed therefore the sound is amplified. Concave surfaces should be avoided in interior spaces as the result is undesirable.Reflection on flat surface Reflection on convex surface Reflection on concave surface3 dousingWhen sound waves strike a surface some of the sound is catched by friction. The materials that run are known as absorbants. Absorption in auditoriums or theatre the takes place in three shipway In Air This absorption happens due to friction between two molecules though this is very fineBy Audience Cloth is an absorbant. So in theatres and auditoriums the sound is absorbed by the clothes o f the audience. Themore the audience the more the absorption takes place.By furniture and furnishing Materials such(prenominal) as cu rtains, carpets absorb sound.The following materials are commonly used for absorption of sound Acoustic Plaster This contains shredded insularity material with cementPerforated and Unperforated compressed cane or wood fibre mount up.Wood part boardCompressed wood sheepskinMineral/ glass wool matsMineral/ glass wool tilesComposite units of perforated hard board backed with perforated fibreboardRequirements of a good acoustical material-Should have high absorption powerIt should be able to absorb a wide look-alike of frequenciesShould be cheap and easily availableShould look attractive after fixing itIt should be farm resistantShould have adequate structural strengthShould be non- hygroscopic.It should be insects and termites free4 locomote detachmentSound insulation/sound proofing is a method used to subdue the level of sound passing through the insulating building component. People generally confuse sound absorption and sound insulation to be the same. The two are very dif ferent from each other. Sound absorbents which are nearly pours materials absorb thus reduce the sound which is reflected from surfaces. On the contrary sound insulating construction reduces sound passing through it. Sound absorbers, are poor sound insulators. While hard material used for sound insulation areinferior sound absorbers.TABLE 4.1. SOUND INSULATION BETWEEN ROOMS SITUATIONOVERALL INSULATION IN db1. Between living room in one house and the living room in another502. Elsewhere between houses or flat403. Between two rooms in the same house.304. Between two class rooms in a tame405. Between two rooms in an office306. Between two wards in a hospital45Impact Insulation- is a rating of how well a building report reduces the impact of sounds, such as footsteps.Sound Insulating Materials Non poriferous harsh partitions- The sound insulation of non- porous wet constructions such as plastered solid brick masonry argues varies. It depends upon the weight per unit area. There is a point when it requires major profit in thicksetness to provide small increase in sound insulation. porous Rigid Materials Porous cover masonry and cinder concrete are some examples of porous rigid materials. They provide 10 part higher insulation as compared to non-porous rigid partitions due to their sound absorptive quality. To enhance the results of insulation it is recommended that porous partitions should be plastered on at least one side and if possible then on both sides. pliant Porous Material These materials provide low insulation. Even lower than rigid materials. Flexible porous materials consists of mineral wool, quilt etc. To increase insulation rigid materials and porous absorbers can be unite together and then applied. This will produce better insulation per unit area.4.1WALL INSULATIONWalls are a vertical barrier of sound. Proper construction of walls can increase the level of sound insulation. Construction of walls for sound insulation can be of four types R igid Homogeneous Walls- Stone, brick or concrete masonry constructions come under this section. The sound insulation in these walls depends upon their weight per unit area. Sound insulation in these increases if the thickness of wall increases. Due to this these walls become uneconomical and bulky after a certain limit. divider Walls of porous materials- These can be rigid or non-rigid. Rigid porous materials such as porous concrete masonry, cinder concrete etc. increase insulation about 10.%. While partition walls of non rigid porous materials provide very low sound insulation. However they can be used if combined with rigid materials.Double wall partition A double wall partition comprises of Plaster boards Or fibre boards or plaster on laths on both sides. With sound absorbing cushion in between. Rough wooden blocks are provided to support the cushion. Double wall partition is a wall of rigid as well as nonrigid porous materials.Cavity Wall Construction- This is said to be the mo st adequate wall construction from the sound proofing point of view. In this two walls are made with a gap of minimum 5cm between them. This gab can be left air filled as we know sound travels the slowest in air or can be filled with some flexible material, like quilt etc. On the surface of the wall celotex or other insulating board may be fixed.4.2FLOOR AND CEILING INSULATIONLike walls are vertical sound barriers as well narrative and ceiling are horizontal sound barriers. The materials used for the construction of floors and ceiling i.e. R.C.C, stone etc. provide great insulation again air borne noise but do not function well for coordinate and impact borne noise. The target of sound proofed floors is to provide insulation against impact and structure borne noise.This can be achieved by the following ways-APPLING RESILIANT SURFACE MATERIALS ON FLOOR In this a thin concrete layer is provided as R.C.C floor slab. On top of this then a soft floor finish or covering is applied. Th is finish or covering can be of linoleum, insulation board, cork, carpet, etc. this helps in reducing impact noises.CONCRETE FLOOR floating CONSTRUCTION This is similar to Cavity wall construction as discussed earlier. In this method we construct an isolated floor from the existing concrete floor. consequently a resilient or porous material like glass wool is laid on the R.C.C flooring. On top of this a water proof sheet is put and then a 5cm thick layer of concrete is given. This kind of construction provides complete insulation against impact sounds.TIMBER FLOOR FLOATING CONSTRUCTION In case of wooden flooring the problem of sound insulation is even more. This action is similar to concrete floor floating construction. The only difference is that mineral or glass wool quilts are used for isolation purpose. At times sand or ashes are also used for isolation.CONCLUSIONSound is mechanical wave which travels through a medium. Sound can be pleasing as well as disturbing. Its necess ary to emit disturbing sounds to have the perfect involve atmosphere. To make an area sound proof its walls/partitions, floor and ceilings need to be treated and insulated. The methods of insulation as discussed above are some ways through which sound proofing can be done. Sound proofing or insulation is the method by which transmission of sound waves can be bard from passing from one area to another.ReferencesBuilding Constructions by B.C Punamia. Sound Insulationhttp//www.meritnation.com/ask-answer/question/how-many-characteristics-a-sound-wave-have.www.scribd.com/doc/102689279/acoustics-ppt