NOISE : PRINCIPLES

INTRODUCTION

HEARING IS ONE OF MAN’S MOST IMPORTANT COMMUNICATION

CHANNELS.

NOISE IS THE TERM USED FOR THE UNWANTED SOUND. THUS THE DEFINATION

OF NOISE IS SUBJECTIVE. ONE MAN’S SOUND CAN BE OTHER MAN’S NOISE

IN RURAL LIFE SOUNDS RARELY BECOME NOISE.

URBANISATION BRINGS ABOUT A RAPID INCREASE OF NOISE SOURCES

(INDUSTRY, TRAFFIC, RAILWAY, AIRCRAFT, ETC.)

IN CARRYING MEDIUM (E.G. AIR), THE STRENGTH OF THE SOUND IS USUALLY

MEASURED AS INTENSITY.

DEFENSIVE MEASURES

THE SCIENCE OF SOUND – ACOUSTICS – CAN BE BRODLY DIVIDED INTO TWO MAJOR AREAS:

1. THE HANDLING OF WANTED SOUND

I.E. CREATING OF THE MOST FAVOURABLE CONDITIONS FOR LISTENING TO A SOUND WE WANT TO HEAR ROOM ACOUSTICS

2. THE HANDLING OF UNWANTED SOUND

I.E. THE CONTROL OF NOISE

DIFFERENT

THINGS

AFFECT

SOUND

• DISTANCE

WIND

TEMPERATURE

DAY

NIGHT

SCREENING AND BARRIERS

SCREENING THE BARRIERS IN THE PATH OF SOUND CAN CREATE AN ACOUSTIC SHADOW.

IF THE SOUND IS OF A LOW FREQUENCY THEN THE DIFFRACTION WILL OCCUR AT THE EDGE OF THE BARRIER.

LOW

FREQUENCY

HIGH

FREQUENCY

SOUND

TRANSMISSION

NOISE CONTROL

MEANS OF NOISE CONTROL

o DISTANCE

o SCREENING

o PLANNING

o REDUCTION AT A SOURCE

o REDUCTION WITHIN SPACE

o ABSORBENT QUALITIES OF DIFFERENT MATERIALS

DISTANCE

“MORE

THE DISTANCE

LESS

THE NOISE”

SCREENING

NOISE CAN BE

REDUCED BY

DESTRUCTING THE

PATH.

PLANNING

TWO WAYS OF

PLANNING

Non noise sensitive

areas (commercial

blocks) near the noise

source (road).

HOUSE PLANNING

SENSITIVE AREAS SUCH

AS BEDROOM, DECK,

LIVING ROOM, STUDY

ROOM SHOULD BE

KEPT AWAY FROM THE

NOISE SOURCE.

REDUCTION AT OR

NEAR SOURCE

BY DIFFERENT

ARCHITECTURAL ELEMENTS

WE CAN REDUCE NOISE.

REDUCTION

WITHIN A SPACE

THERE ARE TWO TYPES

OF NOISE

DIRECT NOISE

REVERBERANT

NOISE

ABSORBENT QUALITIES OF DIFFERENT MATERIALS

POROUS ABSORBENT MEMBRANE ABSORBEnT

PERFORATED PANEL ABSORBENTS

NOISE PROBLEMS IN THE TROPICS

MAIN SOURCES OF NOISE

AURAL REQUIREMENTS

SOUND ABSORPTION

MAIN SOURCES

OF NOISE

THE MAJOR NOISE

SOURCES IN AN

INDUSTRALISED SOCIETY

NOISE SOURCE

AURAL REQUIREMENTS

ACCOUSTICAL

ARCHITECTURAL

DESIGN.

ROOM ARRANGMENT

BALCONIES

BARRIES

THE AURAL REQUIRMENT MAY BE DEFINED AS THE HEARING

REQUIREMENTS .

THE SOCIAL ATTITUDE OF PEOPLE:THEIR NEED FOR PRIVACY

AND THE AURAL REQUIRMENTS.

NOISE IMPACTS CAN

BE REDUCED BYY USE OF SINGLE STORY

HOUSES.

CONSIDERING

ACOUSTICAL WAYS ,

THE BALCONIES

SHOULD BE

DESIGNED.

BALCONIES SHOULD

BE PLACED ON

SHIELDED SIDE OF THE BUILDING.

BARRIERS CAN BE PUT

UP IN ORDER TO HAVE LESS NOISE IN THE

RESIDENTIAL AREA.

THE ARRANGMENT OF

COURTYARD SHOULD

BE DONE WISELY.

SOUND ABSORPTION

PANELS AND BAFFLES ARE

THE MOST EFFECTIVE

BROADBAND ABSORBERS.

THICKER PANELS BETTER

ABSORB LOW FREQUENCY

SOUND. THERE ARE ALSO

ACOUSTICAL PANELS ON

THE MARKET THAT ARE

DESIGNED FOR IMPROVED

LOW FREQUENCY

ABSORPTION.

PERFORATED WOOD IS AN

ACOUSTICAL MATERIAL

SPECULAR SOUND

REFLECTIONS OFF OF

FLAT WALL AND

CEILING SURFACES OFTEN PRODUCE

INCONSISTENT POOR

ACOUSTIC QUALITY

THROUGHOUT THE

LISTENING SPACE.

IN A DIFFUSE SOUND

FIELD SOUND LEVEL IS

UNIFORM IN ALL

LOCATIONS AND

FROM ALL

DIRECTIONS.

HOT DRY CLIMATES

IN HOT-DRY CLIMATES

WALLS AND ROOFS ARE

USUALLY OF MASSIVE

CONSTRUCTION.

WINDOWS AND OPENING

ARE TYPICALLY SMALL AND

THEY OFTEN FACE

ENCLOSED COURTYARD.

ALL THESE ARE RATHER

FAVORABLE FROM THE

POINT OF VIEW OF

EXTERNAL NOISE

EXCLUSION.

THE ONLY SPECIAL MEASURE WHICH COULD BE TAKEN FOR THE REDUCTION OF

EXTERNAL NOISE PENETRATION IS THE PROTECTION OF THE SMALL WINDOWS OR VENTILATORS , IN THE EXTERNAL WALLS , FOR THE PERIOD WHEN THEY ARE OPEN

.

THE POINT OF VIEW OF INSIDE NOISES , THE SITUATION MAY BE SOMEWHAT BETTER THAN IN THE HOT-DRY CLIMATE COURTYARD HOUSE, INSIDE SOUND ARE FREE TO ESCAPE ,WILL NOT BE REFLECTED

FROM BOUNDING SURFACE AND THERE WILL BE NO BUILD-UP OF A REVERBERANT SOUND.

THE ONLY POTENTIAL

SOURCE OF

DISCOMFORT ARE THE

NOISES PART INSIDE THE COURTYARD ,

IT MAY BE HELPFUL IF

SOFT SURFACES ARE

USED PRACTICALLY ,

E.G. LAWN INSTEAD OF

PAVING ,

OR ABSORBENT

MATERIALS ON THE SOFFIT OF THE

VERANDAH ROOF

AROUND THE

COURTYARD.

Warm and humid

climates

BUILDINGS ARE TYPICALLY

LIGHTWEIGHT

CONSTRUCTION WITH

LARGE OPENINGS

EXPOSED TO WIND AND

AIR MOVEMENT.

THE BUILDING ENVELOPE

WILL NOT BE ABLE TO

CONTROL NOISE.

IT CAN REDUCE THE

PENETRATION OF OUTSIDE

NOISE BY SKILFUL USE OF

ABSORBENT SURFACE.

NOISE CONTROL

DENSITIES IN THIS CLIMATE

ARE AND SHOULD BE MUCH

LESS THAN IN OTHER CLIMATE

ZONES.

DISTANCES BETWEEN

BUILDINGS MUST BE KEPT

GREATER TO ALLOW AIR

MOVEMENT TO

CONTROL THE NOISE.

AIR CONDITIONING IMPLIES A

SEALED ENVELOPE ,WHICH IN

TURN MAKES POSITIVE NOISE

CONTROL FEASIBLE.NOISE

CONTROL REQUIREMENTS

,ESPECIALLY IN THE CASE OF

HIGHLY NOISE

SENSITIVE BUILDINGS,WOULD

ASSIST OR REINFORCE THE

CASE FOR THE INSTALLATION

OF AIR CONDITIONING.

THANK YOU…

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