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A
WRITE UP
ON
ACOUSTIC PROPERTIES
OF
BUILDING MATERIALS
COMPILED BY
ARC/01/9223 IJATUYI Olufunto T
ARC/01/9246 OYEKU Mobolaji J.
ARC/03/1930 ODUBENA Olawale O
SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT
FOR THE AWARD OF BACHELOR OF TECHNOLOGY IN
ARCHITECTURE
TO
THE DEPARTMENT OF ARCHITECTURE
SCHOOL OF ENVIRONMENTAL TECHNOLOGY
FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE
Lecturer: Prof. Olu Ola Ogunsote APRIL 2007
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TABLE OF CONTENT pages
ABSRACT iii
1.0INTRODUCTION 1
2.0BUILDING ACOUSTICS AND MATERIALS 2
3.0ACOUSTIC PROPERTIES OF SPECIFIC BUILDING MATERIALS 4
3.1Sound absorptive properties of materials 4
3.2 Sound reflective properties or transmission loss of materials 11
4.0CONCLUSION 15
5.0RECOMMENDATIONS 15
6.0 REFERENCES 15
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ABSTRACT
Acoustics in a higher citadel of learning, as a matter of fact as a course under the
department of architecture is a necessity.
This came to life with the need for students to understand the acoustics of spaces
both interior and exterior, as well as to be able to design acoustically functional spaces
that will enhance the intelligibility of sound or speech.
In addition to this, there is a rapid increase in loss of hearing caused by agents of
hearing damage such as threshold shifts, sociocusis, due to an uncontrolled means of
sound propagation. Hence, the need for the study of acoustics and infact the materials
used to enhance it.
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1.0INTRODUCTION
What is acoustics?
Acoustics is a term sometimes used for the science of sound in general. It is more
commonly used for the special branch of that science, architectural acoustics, which deals
with the construction of enclosed areas so as to enhance the hearing of speech or music.
It could as well be regarded as the branch of architecture that deals with the control of
sound which showcases the reflective, absorptive properties of sound.
Acoustics is a subject that describes all aspects of sound and falls into the fields of
both science and art. The science of sound envelops the technicalities of its generation,
propagation and reception as well as objectively describing its qualities. In the artistic
world, sound plays a large part in terms of the spoken word, music and other auditory
experiences that give us pleasure.
In most cases, the acoustics of a room will be satisfactory if a proper balance
between sound-absorbing and sound-reflecting materials is created. In achieving this,
reverberation as a factor should be taken into consideration.
For modifying the reverberations, the architect has two types of materials, sound-
absorbent and sound-reflecting, to coat the surfaces of ceilings, walls, and floors. Soft
materials such as cork and felt absorb most of the sound that strikes them, although they
may reflect some of the low-frequency sounds. Hard materials such as stone and metals
reflect most of the sound that strikes them. The acoustics of a large auditorium may be
very different when it is full from when it is empty; empty seats reflect sound, whereas an
audience absorbs sound.
Hence, a study of the acoustic properties of various building materials in order to
broaden the scope of the students of architecture and to facilitate the selection of quality
materials that will ensure good acoustics all round a space is needed.
It should however be noted that there are various materials used to achieve a good
acoustic in construction, but for the purpose of this analysis, few number of materials will
be mentioned.
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Aims and objectives
The study of the acoustic properties of various building materials is to achieve the
following objective;
1. To ascertain precisely, the type of material that will be used to achieve a
particular sound level within a space.
2. To broaden the scope of the student in the field of acoustics.
3. To help in determining the various uses of different materials.
4. To be able to analyze the acoustics of buildings.
5. To know the wide varieties of materials that is available for the said purpose.
6. To be able to solve the problem of acoustics within an interior space as well as the
exterior space.
2.0 BUILDING ACOUSTICS AND MATERIALS
Noise control as the name suggests, envelops the techniques used to minimize the
effects of unwanted sound and thus optimize environmental conditions. In the
construction industry, Building Acoustics is the term which covers this aspect of sound.
Building Acoustics involves both the control of noise within an enclosed space and the
reduction of noise between rooms or from either outside or inside a building.
Building Material is any one of various substances out of which buildings are
constructed. They come in different forms and are also applied in various ways in
building. Materials in building construction for the purpose of this write-up will be
classified under the four major component parts of a building. This includes the
following;
1. walls
2. floors
3. ceilings
4. roofs
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Components Of Building And Their Materials
1. WALLS: This is regarded as flat side of building or room, a vertical structure
forming an inside partition or an outside surface of a building. It can as well be seen
as a standing structure that surrounds or blocks,a narrow upright structure, usually
built of stone, wood, plaster, or brick, which acts as a
boundary or keeps something in or out. Other
materials used in wall construction include,
Glass (as curtain walls), Sandcrete blocks,
Plastics, Tiles (mosaic)
2. FLOORS: It is a part of room to walk on: the flat horizontal part of a room on
which people walk. The material used in construction include,
Timber or wood, Concrete, Tiles, Stones
3. CEILINGS: It is seen as the inside top of room: the overhead surface of a room,
or the material used to line this surface. The overhead surface of a room, opposite the
floor. Usually the term refers to a flat, beamed, or curved surface that conceals the
underside of the roof or the floor above, but it may also refer generally to the exposed
underside. There are several materials used for this
purpose and they include,
Asbestos ceiling boards, Celotex boards,
Timber panels, Plaster of Paris (P.O.P)
Acoustic boards
3. ROOFS: It is the upper covering of building: the outside covering of the top of a
building, or the framework supporting this. They are made of materials such as.
Plastics (acrylics), Aluminium Sheets, Clay tiles, Asbestos
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3.0ACOUSTIC PROPERTIES OF SPECIFIC BUILDING MATERIALS
It is very important to distinguish between sound absorption and sound
transmission loss. Sound absorbing materials control sound within spaces and function by
allowing sound to pass through them relatively easily. They are generally porous and
absorb sound as a result of many interactions. Conversely, a material or system, that
provides a good sound transmission loss is usually non-porous and a good reflector of
sound.
3.1 SOUND ABSORPTIVE PROPERTIES OF MATERIALS
Noise is generally controlled within a space using sound absorbing materials.
Sound absorption relates to the percentage that effectively disappears when the sound
wave hits a body or surface. Sound absorption is evaluated by measuring the
reverberation time of a room. The reverberation time is defined as the time taken for the
noise (sound pressure level) to fall to 60dB below its original level when a sound source
ceases to operate. If the reverberation time is long then the room will be live and the
conditions will be acoustically uncomfortable for most activities. If the reverberation time
is too short then sounds such as music may appear flat and lack character
Assuming that the material has greater sound absorption than the room surface on
which it is installed, the reverberation times which are again measured will now be
shorter than in the empty condition. A hard concrete surface has a very low sound
absorption coefficient (less than 0.05 at most frequencies), whereas a thick carpet and
underlay can approach 1.
Acoustic consultants use the absorption coefficients of materials to estimate the
reverberation times of specific buildings. However, in many rooms for example small
offices, it is sufficient to specify totally covering one or two surfaces with a good sound
absorbing product such as carpet or a mineral fibre tile ceiling.
The following building materials have good sound absorbing qualities;
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Acoustical Ceiling Tiles
Characteristic features
No Fiberglass-Non-Fibrous
Moisture Resistant-Indoor-Outdoor
Impact Resistant
Light Weight Ceiling Tiles
Description of Acoustical Ceiling Tiles
MATERIAL: Semi Rigid Porous Expanded
Polypropylene Acoustical Bead Foam (P.E.P.P.).
PATTERN: Non Abrasive, Slightly Textured, Porous
FEATURES: Lightweight, Impact Resistant, Moisture, Bacteria & Fungi
Resistant, Tackable Surface
APPLICATIONS: Gymnasiums, Auditoriums, Classrooms, Swimming Pools, Ice
Arenas, Clean Rooms, Food Processing Plants, Food Prep Areas, Cafeterias &
Restaurants, Manufacturing Plants, Car Washes, Rooftop and Machine
Enclosures, Gun Ranges, Dog Kennels, Locker Rooms.
THICKNESS: 1 & 2
SIZES: Nominal 2x2, 2x4; Custom Sizes Available
COLOR: White, Charcoal
FLAMMABILITY:ASTM E84, Class A. 1": Flame Spread: 3, Smoke Developed:
84.
2: FlameSpread: 5, Smoke Developed: 11 3
INSTALLATION: Glue up direct or as a lay-in tile in a suspended t-bar grid
system.
WEIGHT: 1" = .25lbs/Sq ft 2" = .45lbs/Sq ft
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Graph showing absorption coefficient in relation to their frequencies
Sound Silencer Acoustic Ceiling Tiles - Sound Absorption / Noise
ReductionMount 125Hz 250Hz 500Hz 1KHz 2KHz 4KHz NRC
12
CeilingE400
CeilingE400
0.460.51
0.590.52
0.420.52
0.490.77
0.760.89
0.860.98
0.550.70
Table showing the Sound absorption/ noise reduction of acoustic ceiling tiles
Sound Silencer - Sound Transmission Loss (STC)
125Hz 250Hz 500Hz 1KHz 2.5KHz 5KHz STC
1"2"1" w/5/8"Gypsum bothsides
6927
5827
71029
81031
101732
152245
91332
Table showing the Sound transmission loss of acoustic ceiling tiles
Noise S.T.O.P Acousti-Board
Characteristic features
Sound Deadening
Sound Absorbing
Insulating
Low Cost
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Description of Noise S.T.O.P Acousti-board
MATERIAL: Recycled Wood Fiber Residue.
PANEL SIZE: 2' x 4' or 4'x 8'
THICKNESS: 1/2"
DENSITY: 15 to 20 lbs. Per Cubic Foot.
WEIGHT: .65 lbs./sq. ft.
INSULATING VALUE: R=1.22 at 1/2" (ASTM C518)
NRC: .35 (ASTM C423)
STC: 26 (ASTM E-90)
APPLICATIONS: Acoustical-Board can be used as a Flooring Underlayment or
as a Damping Layer between Studs and Gypsum Board to Improve Sound
Transmission Class (STC) of Gypsum Drywall Partitions. Schools, Apartments
Buildings, Townhouses, Condominiums. Noise S.T.O.P. Acoustical-Board
meets the Requirements of ASTM-C 208, the Specification for Cellulosic Fiber
Insulating Board.
CAUTION: Noise
S.T.O.P. Acoustic-
Board is Combustible
and May Smolder if
Ignited. Do Not Expose to Flame or Prolonged Excessive Heat Above 212 F
without Sufficient Thermal Protection or Use Between Layers of Noncombustible
Material. Specifications for Cellulosic Fiber.
Foam S.T.O.P Pyramid ( Melamine Foam Sound
Absorber)
Characteristic features
High Performance Absorber
Increased Absorptive Surface Area
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Fiber Free
Class A Fire Retardant
Description ofMelamine Foam Sound Absorber
MATERIAL: Open Cell Melamine Acoustical Foam
PATTERN: Pyramid for Monolithic Appearance
FEATURES: Increased Surface Area, High Performance, Light Weight, Dramatic
Visual Effect
APPLICATIONS: Ceilings, Walls, Industrial, Commercial & Home Audio Markets,
Broadcasting and Recording Studios
THICKNESS: 2, 3 , 4 and Custom SIZES: 2x2, 2 x4 (Custom Sizes
Available)
DENSITY: 0.7lbs/cub. ft.
COLORS: Natural White, Latex or Cleanable DuPont Hypalon Paint - Black,
Light Grey, Almond, White (Custom Colors Also Available)
FLAMMABILITY: ASTM E84, Class 1. Flame Spread: 5; Smoke Developed: 50
INSTALLATION: ASI S.T.O.P Noise Acoustical Adhesive
FOAM STOP: Sound Absorption / Noise Reduction per ASTMC423-90a
125Hz 250Hz 500Hz 1KHz 2KHz 4KHz NRC
2 0.07 0.25 0.60 0.94 0.97 1.08 0.70
3 0.18 0.44 0.96 1.14 1.18 1.19 0.95
4 0.16 0.62 1.10 1.20 1.21 1.22 1.05
Table showing Sound absorption/ noise reduction of melamine foam sound absorber
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Graph showing absorption
coefficient in relation to their
frequencies
Absorptive/Noise Barrier Quilted Curtains
Characteristic features
Equipment Enclosures
Cost Effective Room Dividers
Water & Chemical Resistant
Exterior Applications
Description ofAbsorptive/Noise Barrier Quilted Curtains
MATERIAL: Melamine Foam or fiberglass core, faced with quilted aluminized
fabric. Optional Noise Barrier Septum.
PATTERN: Quilted Diamond Pattern
FEATURES: Effective and durable sound absorber with mass loaded vinyl
barrier option.
APPLICATIONS: Used as an economical, effective noise barrier and sound
absorber to enclose many types of noise sources or work areas. The curtains
can be custom fabricated to almost any application. Can be used in exterior
applications, waste water treatment facilities, industrial, commercial & residential
applications.
THICKNESS: 1, 2, 3", 4"
SIZES: 48 & .54 Wide; Lengths up to 25 (Custom Sizes Available)
COLOR: Silver (Other colors available upon request)
FLAMMABILITY: ASTM E84, Class A. Flame Spread: 23; Smoke Developed: 30
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INSTALLATION: Hook and loop fasteners, grommet hangers, curtain spanport
hardware.
CURTAIN S.T.O.P.: Sound Transmission Loss - ASTM E90Frequency 125Hz 250Hz 500Hz 1KHz 2KHz 4KHz STC
1 Thick w/Barrier
11 16 24 30 35 35 27
2 Thick w/Barrier
13 20 29 40 50 55 32
CURTAIN S.T.O.P.: Sound Transmission Loss - ASTM C423
Frequency 125Hz250Hz500Hz1KHz2KHz 4KHzNRC
1 Thick w/ Barrier 0.12 0.47 0.85 0.84 0.64 0.62 0.70
2 Thick w/ Barrier 0.19 0.99 0.96 0.80 0.57 0.33 0.85
1 Thick w/o Barrier 0.12 0.47 0.85 0.84 0.64 0.62 0.70
2 Thick w/o Barrier 0.19 0.99 0.96 0.80 0.57 0.33 0.85
Tables showing the Sound transmission loss of noise barrier quilted curtains
Relationshi fferent frequenciesp graph showing the absorption coefficient at di
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3.2 SOUND REFLECTIVE PROPERTIES OR TRANSMISSION LOSS OF
MATERIALS
Sound is enhanced within a space through the use of reflectors and diffusers.
Sound absorption relates to the percentage that effectively disappears when the sound
wave hits a body or surface. Transmission loss (TL) is the loss in sound power that
results when sound travels through a partition. The more power that is lost, the greater the
TL. The figure below shows the sound transmission loss in different building materials.
Sound absorption is evaluated by measuring also the reverberation time of a room.
Therefore where possible, we design a space to have an optimum reverberation time for
its use.
Sound transmission loss through building
materials
In construction, different building materials are used for the purpose of acoustics
and these materials vary according to their location and are also based on the amount of
sound required in the space. Also, the idea of curved surfaces is imbibed in a way to
enhance the reflective properties of the room.
The following materials have good reflective properties necessary to enhance a
good acoustics within and outside a space;
Silent Screen Panels
Silent Screen absorption panels are designed to provide
both sound absorption and sound transmission loss. T
panels consist of individual sections, each 12 incheswide, mounted horizontally on top of one another, or
vertically, side by side. Each section consists of a 2 3/4
inch deep, 16 to 22-gauge tray. Typically, the tray is
hese
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filled with six-pound density mineral wool, and covered with a perforated 22-gauge face
panel.VISTA Panels
When some degree of visibility is required for safety or monitoring purposes, EAS
Acoustical Panels can incorporate a high strengthLexan-type material which has a clarity rivaling
glass, but is much stronger. VISTA panels also are
abrasion and ultravioletresistant.VISTA panels are easily combined with mineral
wool filled panels or double wall panels to solve a
wide variety of sight and sound problems.
Reflective Panels
Silent Screen Reflective Panels are designed to provide
sound transmission loss only. The panels consist of
interlocking sections, typically 12 inches wide, and can be
mounted horizontally or vertically. Reflective panels provide
a lightweight, aesthetically pleasing noise wall and
acoustical barrier.
Mass Loaded Vinyl Noise Barrier
Characteristic features
Reduces Sound Transmission
Contains Noise
Improves Communications
Improves Health & Safety
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Noise Transmission Loss (dB) Per Octave Band(HZ)Barriers
125 250 500 1000 2000 4000
STC
2 lb. PSF 16 22 26 32 35 40 31
1.25 lb. PSF 14 18 24 27 33 38 28
1 lb. PSF 13 17 22 26 32 37 26
1/2 lb. PSF 8 13 17 22 27 31 20
Table showing Noise transmission loss of Mass Loaded Vinyl Noise Barrier at
different frequencies
Description ofMass Loaded Vinyl Noise Barrier
MATERIAL: Mass Loaded Vinyl Barrier
PATTERN: Smooth Finish
FEATURES: High density limp material to reduce noise transmission.
APPLICATIONS: Reduced noise transmission through ceilings, walls, floors,
machinery enclosures, duct- work. Apply over suspended ceilings on studs or
joists.
THICKNESS: 1/16 - 1/2lb./sq.ft. 1/8 - 1lb./sq.ft. 1/4 - 2lb./sq.ft.
SIZES: 54 Wide x 20, 30, 60 Rolls - 2x2, 2x4 Sheets, Die Cutting Available
COLOR: Black, Grey (Reinforced), Tan and Clear (Transparent or Translucent)
FLAMMABILITY: UL 94VO
INSTALLATION: Material can be nailed, screwed, stapled or can be reinforced
and grometted and hung like a curtain.
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Picture showing the sound transmission
loss of vinyl noise barrier
Transmission loss through glass
Glass is a universally used material with very reflective properties. It is in most
cases used as curtain walls, as covering to windows as well as doors. It acoustic
properties vary according to its sizes and constituents.
Below are the acoustic properties of glass of different sizes,
Glass type configuration Average
STC(dB)
STC
Rating
RW
(dB)
PSR
%perceive
d sound
reduction
3mm flat 24 26 26 0
12mm flat 32 36 36 50
6.76mm PVB
laminated
3mm/0.76mm/3mm 31 35 35 45
10.76mm PVB
laminated
5mm/0.76mm/5mm 35 37 37 52
9mm stop
sound
4mm/1.0mm/4mm 35 37 37 53
17.4mm Glass
tech
6.38mm/6mmAS/5
mm
32 35 35 45
112 double
window
7mm sound
stop/110AS/5mm
48 50 50 80
Glass block 190x190x80mm 40 42 42 65
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4.0 CONCLUSION
In accordance with the aforementioned principles, examples of building materials
and their functions. It can be said; to achieve an acoustically stable room that will
enhance speech intelligibility, the need for the proper selection of building material
cannot be overemphasized. Therefore the study of acoustics as well as the study of
materials to enhance should be promoted in schools of higher learning.
5.0RECOMMENDATIONS
Since one of the main goals of architectural acoustics is to provide optimum
speech intelligibility and sound quality in auditoriums of public buildings, acoustical
input is required in the construction of new buildings and during the refurbishment of
existing buildings whether they are general purpose or specialized facilities.
The acoustical inputs therefore include the use of materials that are can ensure
good absorption, reflection, transmission and diffusion of sound in order to eliminate the
problems of reverberation and echoes and achieve an equal sensory of sound by an
audience at different locations within the hall.
It is recommended that an acoustician be consulted for professional advice on
design and the use of materials that have good acoustic properties in order to help
optimize acoustics since the success of an acoustical design depends to a considerable
extent upon how completely the acoustician's recommendations are followed in carrying
out the design. Ignoring, or partial acceptance of recommendations usually leads to
acoustical deficiencies in the hall.
6.0 REFERENCES
www.buildings.com
Architectural Surfaces, Inc,
15
Acoustical Surfaces, Inc.
http://www.buildings.com/http://www.buildings.com/Top Related