A

TERM PAPER

ON

ACOUSTIC GUIDELINES FOR ARCHITECTURAL DESIGNS

COMPILED BY:

ADEYEMO A.A. ARC/09/7348

LAWANI O.D. ARC/07/0971

COURSE: ARC 507

ENVIRONMENTAL CONTROL III

(ACOUSTICS AND NOISE CONTROL)

COURSE LECTURER

PROF. OLU OLA OGUNSOTE

ARC. SIKIRU ABIODUN GANIYU

SUBMITTED TO:

THE DEPARTMENT OF ARCHITECTURE

SCHOOL OF ENVIRONMENTAL TECHNOLOGY

FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE

IN PARTIAL FULLFILMENT OF THE REQUIREMENT FOR THE AWARD

OF A BACHELOR OF TECHNOLOGY (B.TECH) IN ARCHITECTURE

JULY 2014

CHAPTER ONE

1.1 INTRODUCTION

Architectural design provide shelter for man in such a way that it must have adequate

amenities, facilities and infrastructures suitable for inhabitants to have proper dwellings that

will improve physical biological and social life.

The goal of this paper is try to offer new perspectives for acoustic conditioning of

rooms and other spaces with a concept different of classical sound isolation but with the idea

of increasing the communication level. Communication is basically about hearing and being

heard. Attractive interior design and comfort are both required for well-being in multi-

purpose halls, restaurants, auditoriums, rooms, etc. Current architectural trends, which favour

strongly reflecting materials like concrete or glass, do not aid acoustic requirements in such

spaces. In order to achieve acoustic comfort, a room must exhibit an adequate reverberation

time down to low frequencies.

Furthermore, depending on the main use other quantities such as clarity etc. may also

become important. It is a requirement that acoustic comfort and attractive design can

harmonize, taking into account other relevant factors like light efficiency, accessibility, fire

safety, cleaning resistance, Environmental impact and Indoor climate and so on. Some of

things put into consideration during designing stage are:

Identifying the source of unwanted and loud sound in architectural drawing.

The effect of noise on the inhabitants

Identifying the criteria for acoustically pleasing environment

To identify the method of transmission of noise in architectural drawing

1.2 SCOPE OF STUDY

This report covers the behaviour of sound, its transmission, reduction and insulation in

dwellings. It also covers noise control within different building environment and the use of

absorbent material in architectural building.

1.3 JUSTIFICATION OF STUDY

Noise from its definition is the sound that arises as a result of activities been engaged in

which might later has adverse effect on the health of humans, it can lower efficiency of work

and diminish the quality of life of humans, and as such as the need to sensitive various

professional especially architects to put into consideration the problem of noise pollution in

housing designs is necessary so that reduction of noise to the minimum level which is

achieved right from the initial stage of the design.

CHAPTER TWO

2.1 ACOUSTICS, NOISE AND SOUND

2.1.1. ACOUSTIC: Acoustics is the science of sound and it covers two areas, those of room

acoustics and control of noise.

2.1.2. NOISE: Noise is unwanted or damaging sound which interferes with what people are

trying to do, or sound which has an adverse effect on health and safety.

2.1.3 SOUND: Sound is a disturbance, or wave which moves through a physical medium

(such as air, water, or metal) from a source to cause the sensation of hearing in animals.

2.2 PROPERTIES OF SOUND

2.2.1 SOUND WAVES

A sound wave is a longitudinal pressure fluctuation that moves through an elastic medium. It

is called longitudinal because the particle motion is in the same direction as the wave

propagation. If the displacement is at right angles to the direction of propagation, as is the

case with a stretched string, the wave is called transverse. The medium can be a gas, liquid,

or solid, though in our everyday experience we most frequently hear sounds transmitted

through the air. They are characterized by velocity (v), frequency (f), wavelength (٨), and

amplitude (a). Compression in sound waves is a region of raised pressure. Rarefaction in sound

waves is a region of lowered pressure.

2.2.2 SPEED OR WAVE VELOCITY

This is the speed with which sound travels through a medium. Its symbol is C and it is

measured in units of metres per seconds (m/s).

The relationship between the speed (C), frequency (F) and wave length (٨), C=F ٨

Factors that affect the speed of sound through a medium:

• Elasticity of the medium

• Density of the medium

• Temperature of the medium

2.2.3 AMPLITUDE (a)

This indicates the intensity of sound. Its symbol is I and it is measured in units of watts per

metres square (W/m²).

The inverse square law of sound states that the intensity of sound in a free field is indirectly

proportional to the square of the distance from the source. This infers that there is a decrease

in the intensity of sound the farther the observer is from the sound.

2.2.4 FREQUENCY

This is the number of vibration cycles per seconds. The time interval over which the

motion recurs is called the period. For example if our hearts beat 72 times per minute, the

period is the total time (60 seconds) divided by the number of beats (72), which is 0.83

seconds per beat. We can invert the period to obtain the number of complete cycles of motion

in one time interval, which is called the frequency.

The relationship between frequency and period,

f = 1/T where f = frequency (cycles per second or Hz) and T = time period per cycle (s)

The frequency is expressed in units of cycles per second, or Hertz (Hz), in honor of the

physicist Heinrich Hertz (1857–1894).

2.2.5 PITCH

This is the property of sound that is perceived as highness and lowness depending on the

rapidity of the vibrations producing it. It is measured in cycles per second (cps).

Spherical wave fronts: These are produced when sound spreads out from a point source in

a free space. The wave fronts are spherical and the sound pressure level decreases 6 dB

for each doubling of distance.

Cylindrical wave fronts: These are produced when sound spreads out from a line source

(such as a road with constant traffic or a pipe carrying fluid). The waves are cylindrical

and the sound pressure level decreases 3 dB for each doubling of distance.

Perpendicular wave fronts: These are produced when sound spreads out from a plane

source (such as close to a large vibrating panel or sound travelling down a duct). The

waves are perpendicular and the sound pressure does not decrease with distance.

2.3 MEASUREMENT OF SOUND

2.3.1 SOUND POWER

This is the fundamental property of the source of sound that depicts the energy emitted by a

sound source per unit time. Its symbol is W and it is measured in units of Watts (w). A source

that emits power equally in all directions is called an omnidirectional source. Any other

source is called a directional source.

The sound power is much like the power of a light bulb in that it is a direct characterization

of the source strength. Like other acoustic quantities, the sound powers vary greatly, and a

sound power level is used to compress the range of numbers.

2.3.2 INTENSITY OF SOUND

Sound intensity at a point in the surrounding medium is the power passing through a unit

area. Its symbol is I and it is measured in units of watts per metre square (W/m²).

For an omnidirectional point source the sound power is spread over the surface of the sphere.

S=4pr².

Hence the sound intensity is given by

I=W/4r²

The relationship between sound intensity and sound pressure is given as

I=p² / rc

This equation is for plane waves. However, away from a point source, spherical waves

approximate plane waves. I is the sound intensity in watts per metre square (w/m²),

p is the sound pressure in pascals (pa), r is the density of the medium in kilogram per metres

cube (kg/m³), and c is the speed of sound in metres per second

(m/s).

2.3.3 SOUND PRESSURE

This is the force per unit area and it gives the magnitude of the sound wave. Its symbol is p

and it is measured in units of Pascal (Pa). The pressure changes produced by a sound wave

are also known as sound pressure. Compared with atmospheric pressure on which they are

superimposed (about 100,000 pascals), they are very small (between 20 micropascals and 200

pascals).

2.3.4 THRESHOLD OF HEARING

Audible sounds range from the threshold of audibility to the threshold of pain. The threshold

of audibility is the lower Limit of hearing and it has a standard value of 1 pico-watt per metre

square (1pW/m²). Sounds produced by various sources can range from frequencies below

20Hz to 20,000Hz and above. Infrasound is sound with frequencies below 20Hz.Ultrasound

are sounds with frequencies above 20,000Hz.

2.3.5 THRESHOLD OF PAIN

The threshold of pain is the upper Limit of hearing and it has a standard value of 1 watt per

metre square (1W/m²). Sounds below the lower limit of hearing are inaudible while those

above the upper limit may cause pain or even damage the human ear.

2.3.6 DECIBEL

The sound level or decibel scale is the logarithm of the ratio of measured sound intensity to

the intensity at the threshold of audibility.

The loudness of a sound is determined by referring to the loudness or phon scale which

shows sounds of various levels and frequencies which are perceived as of the same sound

loudness.

2.4 INDUSTRIAL NOISE

Noise is one of the most common occupational hazards Results in many workers being

affected by noise induced hearing loss. Risk due to exposure to high noise levels can be

reduced by:

Elimination: This is the first step that should be considered when addressing exposure

to noise at a workplace. After a critical examination of all existing processes it may be

possible to eliminate the exposure entirely by changing one or more operations.

Substitution: This is the process whereby replacement or buys quiet machinery for the

previous which is possible in most area. This minimizes the need for noise control

later, which can be very costly. When purchasing new plant specification of

maximum noise levels during the tendering process or obtain noise emission data

before purchasing to choose quietest available and affordable plant.

Isolation: This is the process of separating noise sources from people involved in the

work or others standing nearby. It could mean relocating the noise source or

relocating the operators or others to positions away from the noise source.

Engineering control at source and in the transmission path.

2.5 RESIDENTIAL NOISE

The object of noise control in residential building is the reduction of unwanted sound

to tolerable levels. The first step is therefore to determine what constitutes unwanted noise.

The normal practice is to refer to standards that give acceptable noise levels for different

situations and buildings. The source of the noise should then be determined.

The major sources of noise are road traffic, railways, aircraft, industry, office,

machines, people, home appliances, motorized appliances, etc

Which these sources of noise can be broadly divided into two categories, external noises and

internal noises.

2.5.1 CONTROL OF EXTERNAL NOISES

External sources of noise can be controlled by:

Screening: This is most commonly used in controlling traffic noise, as in the case of a

highway passing near a housing estate. The screen can be made from walls, hedges or

other barriers. Landscaping plays an important role in the choice of screens. The most

effective position for a screen is nearest the source.

Planning: This is the process of placing buildings as far away as possible from noise

sources. Noise-sensitive buildings are placed farthest and they receive additional

protection from less noise-sensitive buildings such as garages, workshops and stores

which are placed nearer the noise source. In cases where there are strongly directional

sources of sound, noise bands should be avoided in the location of buildings. Trees

and landscaping are additional tools that may be used.

Building design: This is the process of placing the functional layout of buildings

should place 'noisy' zones such as bathrooms and kitchens nearer the noise source.

Quiet areas (bedrooms), will thus be protected. The position and orientation of

openings should prevent noise penetration and special elements such as wing-walls

and screens may be used as additional protection.

Insulation: This is the process whereby use of sound insulating materials in external

walls and openings can reduce external noise. Increasing the thickness of walls and

reducing the size of openings in them improves their sound insulation.

2.5.2 CONTROL OF INTERNAL NOISES

Internal sources of noise can be controlled by:

Reduction at source: This is usually applicable when noise is due to vibrating

machinery. Flexible mountings are used to prevent transmission of vibration to the

building structure. In the case of airborne sound, an insulating enclosure around the

source is used.

Use of absorbent screens and surfaces: The use of absorbent materials on critical

surfaces of an enclosure can be efficient in reducing reverberant noise when the

source of noise is within the enclosure. There are four types of absorbent materials are

porous absorbents (best for high frequencies), membrane absorbents (best for low

frequencies), resonant absorbers (resonators) and perforated panel absorbents.

Insulation: The transmission of sound between enclosures can be effectively reduced

by sound insulation. Noisy equipment such as generators may thus be placed in well

insulated enclosures. Airborne sound can be reduced by airtight and noise insulating

constructions. Structure-borne sound can be reduced by creating 'sound gaps'

separating structures (walls).

Building design: Noise from within a building originates from people, bathrooms,

kitchens and appliances. The normal practice is to group noisy zones together. Thus in

a multi-storey housing block, the stairs, lifts, corridors and sometimes kitchens and

laundries are grouped together. The quiet zones (study, bedroom) are grouped

separately. This spatial segregation can effectively reduce noise transmission

especially when combined with insulation.

2.6 RECOMMENDED ACOUSTIC STANDARDS

Acoustic standards are available for various types of buildings. These standards

establish how noise sensitive different buildings and spaces are. Thus educational buildings

are less noise tolerant than industrial buildings. The standards for outdoor situations are

usually higher than those for indoors. There is sometimes a need to apply corrections to the

standards. The standards are set for daytime conditions and a reduction for the evening and

night time periods is therefore needed.

Daytime no correction

Evening 3 dBA

Night -10 to -15 dBA

Outdoor standards may provide a guide to the indoor standards after making

corrections for the insulation of facades with windows:

Windows open -10 dBA

Single window shut -15 dBA

Double window shut -20 dBA

Non-openable window -20 Dba

2.7 BUILDING DESIGN AND CONSTRUCTION

In multi-storey building cases, the major forms of noise transmission structure borne and

Impact sound. This problem can be solved by the provision of medium between the sound of

the noise and the solid structure of the building especially from the impact noise. It is

essential that:-

Residence of the damping material necessary which means that elastic limit should

not be exceeded even during long period of usage.

The material used as insulation, damping material should not have the same frequency

as source of the sound being transmitted. If this is reduced rather than increased due to

resource, it is necessary for the ratio of facing frequency to natural frequency to

exceed 1.4 for insulation to occur, and for all practical purpose we should aim at an

insulation system where the natural frequency is less than about 1/3rd

of the lowest

frequency to be expected in the sound against which it is desirable to insulate.

The system is continuous without any sound bridges such as nails or screws causing

sound across.

CHAPTER THREE

3.1 ACOUSTIC REQUIREMENT IN ARCHITECTURAL DESIGN

Some individual living spaces in an architectural design are sensitive to noise while some are

not, as a result of this, the finishes within these individual living spaces vary from function to

function, and also the location of the spaces in the design also varies. Here in this chapter,

some vital functions within an architectural design would be treated and then acoustical

requirements identified.

The spaces to be considered are

1. Living Room

2. Dining

3. Kitchen/Laundry/Garage

4. Bedroom

5. Study

3.2 LIVING ROOM

The living room is an expression of our own age and way of living. This similarities with a

different is true of all activities, dancing, playing, eating, drinking and entertaining guest, so

it is only to be expected that today’s house plans and finishing are different.

One of the activities expected in the heart of the main lounge is conversation; sitting is

another. One might pick up a book and read a whole or listen to a favourite program on the

radio or turn on the television.

If friends are around a game of cards, could be enjoyed or dancing or singing or simply

sitting and talking. One might just doze before the fire and dream a whole. Some evenings

one might sit alone, work on a stamp collection, write long letters or listen to the record

player. At times, it serves as dining and sleeping rooms. For all activities in a living room, it

must be designed and palmed so that noise will not be of disturbance in the space. Noise can

be controlled in the living room via two measures.

Through Design: In designing a building, the living room should be located in a way

that noise from the surrounding building will be prevented from penetrating into the space. If

this cannot be derived, sound blocking rooms like ante-room, reception, deep balcony can all

be of help in reducing the noise from outside the building. Living room must be isolated from

the noisy zones in the design, for example kitchen. In some designs where the kitchen is also

part of the living room, the dining can act as a shielding function between them.

Contents and Finishes: The contents and finishes of the living room would aid

control noise in this function. The use of acoustic tiles, screens, rugs, and even upholstery of

the furniture itself may be used to control sound in living rooms.

3.3 DINING AREAS:

The dining area may be a separate room or it may be a part of the living space or of the

kitchen but no matter the location it should be as delightful and charming place as it can be.

For many families dinner is important, not only for the food it provides but also because it is

a time for family gathering or union, one of the few time’s during the day when all the

members of the family have an opportunity to chat with one another.

In most families, breakfast is almost an individual affair due to the rush in the early hours and

lunch at home is often impossible for the commuter and the school child; this makes dinner

therefore a special family significance and the room should be designed to encourage

relaxation conversation and a feeding of peace.

Noise in the during might come from the clatter of dishes, the adjustment of chairs

before one sits or from the kitchen; all those are cause unnecessary distractions and can be

eliminated from the dining area by acoustical tiles used on the ceiling or walls or by the use

of draperies and a rug.

3.4 KITCHEN/LAUNDRY/GARAGE

Most noise generated with the design interior is from activities inside the kitchen, laundry or

garage. Locating these spaces away from the quiet zones in the house is one major way with

dealing with internal noise, apart from that, noise control in these spaces can be achieved by

the use of sound absorbent materials like wood for all cabinets in the kitchen and laundry.

Also instead of terrazzo floor finishes, the use of linoleum, vinyl cork and vinyl will help in

reducing the noise in the room when there is impact with the floor.

3.5 BEDROOM

The bedroom is meant to be most quiet of all the functions in the design. The average

individual sleeps eight hours in a day, meaning, the bedroom is used a third of each living

day just for the purpose of sleeping.

Other activities can also take place in the bedroom, activities requiring extra hours. The noise

and movements of the night disturbs the sleeper, a heavy truck roars down the street and your

sleep is broken. A sudden sends one stumbling through the house half asleep to close

windows, a second occupant moves across the bedroom floor and every footstep sound

loudly. Annoyances like these, which seem gigantic at night, are forgotten in the day time

until they occur again at night. Be it that your bedroom is as scientific as the latest design or

as traditional as the one Washington’s Mount Vernon, the chief requirement of a bedroom are

quietness, privacy and good ventilation. Many of the problems of sound, privacy, and

ventilation in bedroom can be palmed at the key begging Rogers (1962).

3.6 STUDY

This function is common to high income earners. In other income stratifications, the bedroom

is best used as a study. However, the study room must be located away from the noisy part of

the design. The furniture used inside the study room also should be a good sound absorber.

CHAPTER FOUR

4.1 RECOMMENDATION AND CONCLUSION

The architect should inspect the site before commencing design for structures should

be done by the architects, putting into consideration the noise problem at the

commencement of the design before identifying the possible major source of noise at

the site location.

The clients should ensure that lands marked on buffer zones or reserved areas should

not be bought by them, also the architect’s specification of finished materials should

be used adequately and properly as specified by the architect.

The architect should also ensure that quiet zones of the design are moved away from

the noise source while shredded by other functions like the ante rooms or kitchen; this

must be explained to the client however because of the need to check noise intrusion

into quiet zones.

The planners must be thought with the allocation of land for users. The right land

must be used for the purpose of which it is proposed for.

Dwellers of the buildings should ensure planting of trees around their sites as this aids

in shielding noise from the building interior to a certain level, also they should

maintain the facilities provided for noise reduction in their apartment and obey the

regulation of the architectural design.

4.2 CONCLUSION

This paper actually made it clear that major source of noise in the architectural design is from

traffic, railways, aircraft, office, machines, people, home appliances, motorized appliances,

commercial, and industrial activities. It was also understood that proper analysis of the site

and investigation relating to site surroundings helps in acoustics planning.

REFERENCES

Marshal Long(2006); Architectural Acoustic

Professor Olu Ola Ogunsote Acoustic And Noise Control Lecture notes

Harris, C.M (1975); dictionary of architecture and construction. Pub McGraw Hill

Book company.

Salvato A. J. (1982); environmental engineering and sanitation. Third edition, john

wiley and sons’ inc.

Knister E. L, Frey A. R, Coppen A.B and Sanders J.V. (1982); fundamentals of

acoustics, third edition, john wiley and co.

http://www.sdecng.net/Files/Lectures/FUTA-ARC-507/Assignments