A

WRITE – UP

ON

ACOUSTIC PROPERTIES

OF

BUILDING MATERIALS COMMONLY USED

FOR CONSTRUCTION OF HOUSES IN NIGERIA

COMPILED BY

AKINSIPE AYOOLA

(ARC/09/7356)

GROUPA-8

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

Arc. Ganiyu

JULY, 2014

ii

TABLE OF CONTENT pages

ABSRACT…………………………………………………………………………………...iii

1.0 INTRODUCTION………………………………………………………………………. 1

2.0 BUILDING ACOUSTICS AND MATERIALS………………………………………. 2

3.0 ACOUSTIC PROPERTIES OF SPECIFIC BUILDING MATERIALS…………… 4

3.1 Sound absorptive properties of materials…………………………………….. 4

3.2 Sound reflective properties or transmission loss of materials……………… 11

4.0 CONCLUSION …………………………………………………………………………15

5.0 RECOMMENDATIONS……………………………………………………………….15

6.0 REFERENCES………………………………………………………………………….15

iii

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.

1

1.0 INTRODUCTION

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.

2

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

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)

3

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

3.0 ACOUSTIC 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

4

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;

● 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

5

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 2’x2’, 2’x4’; 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

Graph showing absorption coefficient in relation to their frequencies

Sound silencer-sound transmission loss(STC)

125Hz

250Hz

500Hz

1Hz

2.5Hz

5Hz

STC

1"

6 5 7 8 10 15 9

2"

9 8 10 10 17 22 13

1" w/5/8" Gypsum both sides

27 27 29 31 32 45 32

Table showing the Sound transmission loss of acoustic ceiling tiles

6

● Noise S.T.O.P Acousti-Board

Characteristic features

▪ Sound Deadening

▪ Sound Absorbing

▪ Insulating

▪ Low Cost

● 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

7

• Fiber Free • Class A Fire Retardant

● Description of Melamine 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: 2’x2’, 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 ASTM C423-90a

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

●Absorptive/Noise Barrier Quilted Curtains

Characteristic features

• Equipment Enclosures • Cost Effective Room Dividers • Water & Chemical Resistant •

Exterior Applications

● Description of Absorptive/Noise Barrier Quilted Curtains

8

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

INSTALLATION: Hook and loop fasteners, grommet hangers, curtain spanport

hardware. CURTAIN S.T.O.P.: Sound Transmission Loss - ASTM E90 Frequency 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

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

9

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. Tpanels consist of individual sections, each 12 inches wide, 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

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 strength Lexan-type material which has a clarity rivaling glass,

but is much stronger. VISTA panels also are abrasion and ultraviolet resistant.

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 •

16 22 26 32 35 40 31

10

Improves Health &

Safety2 lb. PSF

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

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.

11

Below are the acoustic

properties of glass of

different sizes, Glass type

configuratio

n

Average

STC (dB)

STC

Rating

RW

(dB)

PSR

%perceived

sound

reduction

3mm flat 24 26 26 0

12mm flat 32 36 36 50

6.76mm PVB laminated 3mm/0.76m

m/3mm

31 35 35 45

10.76mm PVB

laminated

5mm/0.76m

m/5mm

35 37 37 52

9mm stop sound 4mm/1.0mm

/4mm

35 37 37 53

17.4mm Glass tech 6.38mm/6m

mAS/5mm

32 35 35 45

112 double window 7mm sound

stop/110AS/

5mm

48 50 50 80

Glass block 190x190x80

mm

40 42 42 65

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.

5.0 RECOMMENDATIONS

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

12

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,

Acoustical Surfaces, Inc. 15

Mazer, S. E. (2005, March/April). Reduce errors by creating a quieter hospital environment.

Patient Safety & Quality Healthcare. Retrieved March 25, 2010, from

http://www.psqh.com/marapr05/noise.html

Ryherd, E. E., Waye, K. P., & Ljungkvist, L. (2008). Characterizing noise and perceived

work environment in a neurological intensive care unit. Journal of the Acoustical Society

of America, 123(2), 747-756.

Daly, P. (2009, June 15). Shhhh! Hospital acoustic upgrades under construction. Grand

Rapids Business Journal.Retrieved March 3, 2010, from

http://www.grbj.com/GRBJ/ArticleArchive/Article+Archive.htm?Channel={A7AFA10B-

CAAB-4988-BAC9-B10793833492}

RWDI Consulting Engineers (n.d.). Noise and acoustics for healthcare design. Technotes, 32.

Retrieved March 3, 2010, from http://www.rwdi.com/cms/publications/51/t32.pdf

Busch-Vishniac, I., West, J., Barnhill, C., Hunter, T., Orellana, D., & Chivukula, R. (2005).

Noise levels in Johns Hopkins Hospital. Journal of the Acoustical Society of America,

118(6), 3629–3645.