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Acoustics and sound insulation PREPARED BY MANISH KUMAR LECTURER ARCHITECTURE AT GOVT. POLY. COLLEGE FOR GIRLS PATIALA 1 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 2 GENERAL INTRODUCTION Sound is generated in the air when a surface is vibrated. The vibrating surface sets up waves of compression and rarefaction. To understand it let us take example of tuning fork 2 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 3 GENERAL INTRODUCTION I have drawn three pictures of a tuning fork to help you visualize how air molecules might look around a tuning fork. When the tuning fork is at rest, the fork is surrounded by molecules in the air. 3 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 4 GENERAL INTRODUCTION As a tuning fork's prongs move apart because of a vibration. The molecules ahead of it are crowded together. They look like they are being pushed together. They bump each other. 4 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 5 GENERAL INTRODUCTION As the tuning fork's prongs come back together, it leaves a region that has fewer molecules than usual. The region of a sound wave in which the molecules are crowded together is a compression. The region of a sound wave in which particles are spread apart is a rarefaction. 5 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 6 GENERAL INTRODUCTION As a tuning fork vibrates, it causes molecules in the air to move. The molecules bump into other molecules nearby, causing them to move. This process continues from molecule to molecule. The result is a series of compressions and rarefactions that make up sound waves. 6 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 7 GENERAL INTRODUCTION And these compression and rarefactions sets the ear drum vibrating. The movements of ear drum are translated by the brain into sound sensation. So, we really don't hear with our ears - we hear with our brains! 7 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 8 GENERAL INTRODUCTION Shape (dish type) of the outer ear is helpful in receiving sound waves. 8 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 9 GENERAL INTRODUCTION Here's How It Works Sound vibrations, or sound waves, are collected by the OUTER EAR. And travel into the ear canal, where they bump up against the ear drum. The EAR DRUM vibrates in sympathy with these sound waves. As it vibrates, it moves a series of tiny bones in the MIDDLE EAR 9 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 10 GENERAL INTRODUCTION Which carry the vibrations to a fluid-filled tube called the cochlea in the INNER EAR The fluid inside the cochlea vibrates a series of tiny hairs called cilia, which are attached to auditory nerves. The movement of these cilia stimulates the nerves. And they send signals to the brain, which, in turn, processes these signals into the sounds we hear. 10 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 11 GENERAL INTRODUCTION 11 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 12 Characteristics of sound There are three characteristics of sound. Intensity and loudness and it is measured in decibel Frequency and pitch of sound it is measured in Hertz" (Hz) or "cycles per second. Quality or timbre of sound. 12 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 13 Intensity and loudness of sound Intensity of the sound is defined as the amount or flow of wave energy crossing per unit time through a unit area taken perpendicular to the direction of propagation. Intensity of sound is purely a physical quantity which can be accurately measured and is independent of the ear of the listener. 13 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 14 Intensity and loudness of sound Loudness of a sound corresponds to the degree of sensation depending upon the intensity of sound and sensitivity of ear drums. It may also happen that the same listener might give different judgments about the loudness of sound of the same intensity but of different frequencies as the response of the ear is found to vary with the frequency of vibration. 14 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 15 Frequency and pitch of sound Frequency or pitch is defined as the number of cycle which a sounding body makes in each unit of time. It is measure of the quality of sound. The sensation of pitch depends upon the frequency with which the vibrations succeed one another at the ear. Greater the frequency the higher the pitch. And the lesser the frequency the lower the pitch. 15 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 16 Frequency and pitch of sound The audio range falls between 20 Hz and 20,000 Hz. This range is important because its frequencies can be detected by the human ear. A frequency is expressed in terms of Hz(Hertz) and it determines pitch of sound source. They can be categorized as: Low tones sound of urban road traffic. Mild tones sound of piano notes. High tones sound of single tea kettle. 16 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 17 Quality or timbre of sound. The quality of sound is that characteristics which enables us to distinguish between two notes of the same pitch and loudness played on two different instruments or produced by two different voices. It is to be noted that it is that tonal quality which enables us to recognize a large number of different sounds. 17 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 18 The behavior of sound propagation It is affected by many things: The speed of sound within the medium depends upon temperature of the medium,which in turns effect the density and pressure of the medium.. The propagation is also affected by the motion of the medium itself. For example, sound moving through wind is further transported towards the direction of wind. 18 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 19 The behavior of sound propagation The viscosity of the medium also affects the motion of sound waves. It determines the rate at which sound is attenuated. For many media, such as air or water, attenuation due to viscosity is negligible. Sound cannot travel through a vacume. 19 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 20 The behavior of sound propagation It travels much faster in solids and liquids then in air. The velocity of sound in atmospheric air at 20 degree centigrade is 343 meter per second. The velocity of sound in pure water is 1450 meter per second. The velocity of sound in bricks is 4300 meter per second. The velocity of sound in concrete is 4000 meter per second. 20 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 21 The behavior of sound in enclosures When the sound waves strike the surface of room three things happen (1) Some of the sound is reflected back in the room. (2) Some of the sound energy is absorbed by the surfaces and listeners of the room/hall. (3) And some of the sound is transmitted out of the room through vibrations of floors, walls and ceilings. 21 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 22 The behavior of sound in enclosures The amount of sound reflected and absorbed depends upon the different surfaces of room. And the sound transmitted outside the room will depend upon. The sound insulation properties of walls, floors and ceiling etc.. 22 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 23 Reflection of sound waves. Reflection of sound waves is exactly the same as that of light waves. That is angle of incidence is equal to the angle of reflection. *c *c INCIDENT WAVE REFLECTED WAVE REFLECTING SURFACE. 23 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 24 Reflection of sound waves. The reflected wave front from a flat surface are also spherical and their centre of curvature is the image of source of sound. FLAT REFLECTOR WAVE FRONT SOUND SOURCE 24 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 25 Reflection of sound waves. Sound waves reflected at a convex surface are magnified and are considered bigger. They are attenuated and therefore weaker. So convex surface may be used with advantage to spread the sound waves throughout the room. WAVE FRONTCONVEX REFLECTOR SOUND SOURCE 25 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 26 Reflection of sound waves. The sound waves reflected at a concave surface are considered smaller. The waves are most condensed and therefore amplified. The concave surface may be provided for concentration of reflected waves at certain points. WAVE FRONT CONCAVE REFLECTOR SOUND SOURCE 26 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 27 Acoustics general introduction The scientific study of the phenomenon of sound is known as Acoustics. Acoustics as applied to buildings is the science of sound which assures the optimum conditions for Producing sound/speech/music Listening of sound/speech/music Recording /editing of sound etc. 27 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 28 Acoustical Interaction Acoustics means to work on these three parameters and improve sound experience. 28 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 29 Acoustical Interaction Sound is attenuated by absorption Historically, the primary focus of acoustics was the use of absorbing surfaces to control the reverberation times and loudness of spaces. Redirected by reflection Uniformly scattered by diffusion Good architectural acoustic design requires an appropriate combination of absorptive, reflective and diffusive surfaces 29 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 30 Acoustics general introduction For better acoustical results the construction and application of sound absorbents and sound reflective materials should be carefully selected and placed. This will help in providing better quality of audio video sensations to viewers/ listeners. Proper acoustical planning can reduce or completely eliminate defects related to sound,which are called acoustical defects. 30 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 31 Acoustical defects List of acoustical defects Reverberation. Formations of echoes. Sound foci. Dead spots. Insufficient loudness. Exterior noises. 31 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 32 Acoustical defects (Reverberation) Reverberation is the persistence of sound in the enclosed space, after the source of sound has stopped. Reverberant sound is the reflected sound, as a result of improper absorption. Reverberation may results in confusion with the sound created next. 32 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 33 Acoustical defects (Reverberation) However some reverberation is essential for improving quality sound. The time during which the sound persists is called the reverberation time of sound in the hall. As per Prof. W.C. Sabins reverberation time t is given by formula :- t= 0.16V /A where V=volume of room in cubic meters A= total absorbing power of all the surfaces of room/ hall. 33 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 34 Acoustical defects (Reverberation) 34 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 35 Acoustical defects (Reverberation) 35 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 36 Reverberation time & quality of sound Reverberation time should remain within limits as per Indian Standard Code: 2526-1963. Sr. No. RECOMMENDED TIME IN SECONDS ACOUSTICS 10.50 to 1.50Excellent 21.50 to 2.00Good 32.00 to 3.00Fairly good 43.00 to 5.00Bad 5Above 5.0 secondsVery bad 36 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 37 Formation of echoes. Echo's Not all sound that hits matter is absorbed. Some of it is reflected. That means sound bounces off the solid matter the way a tennis ball bounces off a wall. Sound reflected back to its source is an echo. 37 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 38 Formation of echoes. An echo is produced when the reflected sound wave reaches the ear just when the original sound from the same source has been already heard. Thus there is repetition of sound. The sensation of sound persists for 1/10 th of a second after the source has ceased. Thus an echo must reach after 1/10 th second of the direct sound 38 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 39 Formation of echoes. Multiple echoes may be heard when a sound is reflected from a number of reflecting surfaces placed suitably. This defect can be removed by selecting proper shape of the hall. And by providing rough and porous interior surfaces to disperse the energy of echoes. 39 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 40 Sound foci Some times shape of the hall makes sound waves to concentrate in some particular areas of hall creating a sound of large quality. These spots are called sound foci. This defect can be removed by Geometrical design shapes of the interior faces. Providing highly absorbent materials on critical areas (curved spaces). 40 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 41 Dead spots. This defect is the out come of formation of sound foci. Because of high concentration of reflected sound at sound foci, there is deficiency of related sound at some other points. These spots are known as dead spots where sound intensity is so low that it is insufficient for hearing. This defect can be removed by suitably placing diffusers and reflectors. Right proportions of internal spaces. 41 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 42 Dead spots. Geometrical shape of roof helps in proper distribution of sound 42 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 43 External noise External noises from vehicles, traffic engines, factories, machines etc. may enter the hall either through the openings or even through walls and other structural elements having improper sound insulation. This defect can be removed by proper planning of the hall with respect to its surroundings and by proper sound insulation of external walls. 43 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 44 Acoustical design of halls The initial sound from the source should be of adequate intensity so that it can be heard throughout the hall. For halls of big sizes suitable sound amplification system should be installed. The sound produced should be evenly distributed so that there is no dead spots and sound foci. 44 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 45 Acoustical design of halls The boundary surface should be so designed that there are no echoes or near echoes. Desired reverberation time should be achieved by proper placement of absorbents on wall. The out side noise should be eliminated. 45 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 46 Physical Design Principles for halls 46 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 47 Physical Design Principles for halls 47 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 48 Physical Design Principles for halls 48 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 49 Physical Design Principles for halls 49 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 50 Physical Design Principles for halls 50 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 51 Physical Design Principles for halls 51 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 52 Physical Design Principles for halls 52 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 53 Acoustics materials Carpet is an outstanding sound absorptive material. When properly selected, carpet absorbs airborne noise as efficiently as many specialized acoustical materials. No other acoustical material performs the dual role of a floor covering and a versatile acoustical aid. 53 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 54 Acoustics materials QUIET BARRIER HD A flexible, 2lb per sq./ft. 1/4 in. thick, high density material with a smooth surface designed to reduce noise transmission between two spaces. Applications include reducing airborne noise transmission through walls, ceilings and floors 54 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 55 Acoustics materials QUIET BARRIER MD A flexible, 1lb per sq./ft. 1/8 in. thick, high density material with a smooth surface specially engineered to reduce noise transmission between two spaces. 55 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 56 Acoustics materials QUIET BATT Insulation A premium high-performance acoustical/thermal insulation manufactured from 80% recycled cotton fibers. QUIET BATT offers superior noise reduction versus typical fiberglass, cellulose and foam insulations 56 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 57 Acoustics materials Tough core Ceiling Tiles High-performance composite ceiling panel. Especially well- suited to minimize sound transmission between adjacent spaces sharing a common attic space. Available in a variety of finish options and edge details. 57 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 58 Acoustics materials Isotrax Complete soundproofing system for walls and ceilings. Blocks and isolates sound, reduces noise from traveling through building materials. New or existing construction. 58 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 59 Acoustics materials damping tiles used for noise absorption. 59 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 60 Sound insulation general introduction Unwanted sound reaching the ears is called NOISE. It may be due to frequency of sound. It may be due to intensity of sound. Or it may be due to the combination of both frequency and intensity of sound. 60 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 61 61 Sound insulation Slide 62 Sound insulation general introduction So sound insulation is the measure by which transmission of sound / noise from inside to out side (vice versa ) or from one room to other is prevented. 62 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 63 Sound insulation ( effects of noise) It creates discomfort. It has adverse effect on blood pressure, sleep and causes muscular strains. It leads to fatigue and decreases the efficiency of a person. It takes away essence of music and speech. It disturbs concentration. Prolonged exposure to noise may result in temporary deafness or even nervous breakdown. 63 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 64 Classification of noise. From the origin point of view noise may be of two types:- Out door noise. Indoor noise. And noise may also be classified as Air borne noise or sound Structure borne noises or impact noises or sounds. 64 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 65 Sources of out door noises. OUT DOOR NOISES ARE CAUSED BY:- Road traffic. Railways. Climatic conditions. Aero planes. Moving machines. Machines in nearby factories or buildings etc. 65 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 66 Sources of in door noises. Indoor noises are those which are caused either in the same room or adjacent rooms. And these are due to:- Conversation of peoples. Moving of peoples. Moving of furniture. Crying of babies. Playing of radios/ other musical instruments. Operations of water closets and cisterns. Noise of type writer Banging of doors etc. 66 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 67 Transmission loss (TM) of sound When sound is transmitted from source or origin to the adjoining room/ area, reduction in sound intensity takes place. This is known as transmission loss (TM) Measured in decibels (dB) 60 decibels40 decibels TM=60-40=20 DECIBELS. 67 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 68 Acceptable indoor noise level TYPE OF BUILDING NOISE LEVEL IN DECIBLE (dB) Radios and TV studios 25-30 dB Music rooms 30-35 dB Hospitals and auditoriums 35-40 dB 68 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 69 Acceptable indoor noise level Apartments, hotels and homes 35-40 dB Conference rooms, small offices and libraries 35-40 dB Court rooms and class rooms 40-45 dB Large public office, banks and stores 45-50 dB Restaurants 50-55 dB Factories 55-65 dB 69 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 70 Types of sound insulating materials Non porous rigid. Porous rigid materials. Non rigid porous flexible materials. 70 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 71 Types of sound insulating materials Non porous rigid Brick masonry plastered on both sides Stone masonry structures Concrete structures RCC Structures Porous rigid materials. Light weight concrete Cellular concrete Gypsum board partitions 71 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 72 Types of sound insulating materials Non rigid porous flexible materials Perforated boards Compressed fiber boards Pulp boards Mineral wool boards Acoustic tiles /sheets Glass wool 72 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 73 Types of sound insulating materials Non rigid porous flexible materials Cobalt quilt Wood wool boards Curtains Foams Celotex boards Cane fiber etc. 73 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 74 Sound insulating techniques There are some construction techniques also which are adopted for sound insulation. Double wall construction. Cavity wall construction. False ceiling. Hollow block construction. Double pane windows. Baffle blocks, honey combs etc. 74 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 75 Sound insulating techniques Double wall construction. BOARDS WOODEN STUDS SOUND ABSORBING BLANKET BOARDS WOODEN STUDS 75 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 76 Sound insulating techniques Cavity wall construction. EXTERNAL WALL 13MM PLASTERED 5CM CAVITY BRICK WALL 10CM CELOTEX OR OTHER INSULATING BOARD METAL FLY 76 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 77 Sound insulating techniques False ceiling. REINFORCED CONCRETE ROOF SUSPENDERS FALSE CEILING 77 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 78 Sound insulating techniques Hollow block construction. COMPRESSED CONCRETE HOLLOW BLOCKS HOLLOW 78 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 79 Typical insulation values for different type of walls Sr. no. TYPE OF CONSTRUCTIONAPPROX. WEIGHT IN Kg/sq. m Average TL in dB 1One brick thick wall that is 20 cm.485-49050 2One and half brick thick wall that is 30 cm. 705-71053 3Cavity wall having two leaves each of half brick thickness with 5cm cavity. 485-49050-53 4Cavity wall having two 10 cm thick leaves of clinker block with 5cm cavity. 310-31250 79 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 80 Typical insulation values for different type of walls Sr. no. TYPE OF CONSTRUCTIONAPPROX. WEIGHT IN Kg/sq. m Average TL in dB 5Half brick wall with 13mm thick plaster on both sides. 268-27045 620 cm thick hollow dense concrete block wall with 13 mm thick plaster on both sides. 18545 7Partition wall made with gypsum wall board fixed on timber frame work. 60-7045 876 mm thick hollow clay block wall with 13 mm thick plaster on both sides. 108-11036 80 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA Slide 81 Thank you and enjoy sound 81 PRESENTATION BY MANISH KUMAR LEC. ARCHITECTURE AT PATIALA