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A

TERM PAPER

ON

ACOUSTICS ANALYSIS

OF

DIGITAL RESEARCH AND RESOURCE SHARING CENTRE

PREPARED BY

ADEYANJU A.S (ARC/08/3969)

ODUNIYI M. A (ARC/09/7401)

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ABSTRACT

This report details the acoustic analyses of the digital research and resource sharing

centre. The report identifies the major noise sources within and around the building. The

report analyses the basic finishing materials of the building (digital research and resource

sharing centre) components (walls, floors and ceilings). The materials used for the

construction of these building components were also analysed in respect to their acoustic

properties; such as how they absorb and reflect sound. Basic noise sources were identified

and detailed via photographs and computer aided design. A decibel scale was used to

measure noise levels at the source both internally and externally. Methods of improving the

acoustic of the building were highlighted. All data used in this report were gotten through

field work.

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INTRODUCTION

The digital research and resource sharing centre is located at Obanla campus of the

federal university of technology Akure. The building is opposite the university’s chapel and is

adjacent to the university library. The building basically comprises the computer science

study laboratories and offices for staff. The study laboratories are rectangular in shape and

they are cross ventilated.

ANALYSES OF THE BUILDING

The floor finish used in the building (Digital research and resource sharing centre) is

vitrified tiles. Vitrified tiles do have poor acoustic properties. Vitrified tiles due to its hard

and solid nature do not easily absorb sound rather it reflects the sound back at the same angle

as the incident sound ray thereby causing reverberation of sound. Vitrified tiles generate

noise when walked on. Often times the noise generated is annoying and disturbing.

Plate 1.0: showing interior floor finish

Source: Author’s archive (2014)

The wall of the building is sandcrete block finished with emulsion paint. The wall of

the building has very poor acoustic characteristics. The wall of the building is hard and solid

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and the wall finish (emulsion paint) does not absorb sound. Although the rectangular shape of

the building is a good form when it comes to reducing the effects of reverberation of sound.

Sandcrete block wall finished with emulsion paints often reflects sound rather than absorb

sound.

Plate 2.0: showing walls finished with emulsion paints


The material used for the ceiling is polyvinyl chloride (PVC). The ceiling is

aesthetically sound but polyvinyl chloride, when used in the manufacture of ceiling tiles has a

poor acoustic properties. It does not readily absorb sound. Ceiling tiles made with Polyvinyl

chloride reflects sound at the same angle as the incident sound ray. Although not all the

sound is reflected some is been absorbed.

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Plate 3.0: showing polyvinyl chloride ceiling tiles


EXTERNAL NOISE SOURCES

There are several external noises generated around the building. The major external

noise sources are:

1. Vehicular noise

2. Generator noise

3. Air-Condition noise

4. Human noise

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Fig 1.0: Showing site plan of the building


Fig 2.0: Showing floor plan of the building


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Fig 3.0: Showing roof plan


Fig 4.0: showing section thoroughly worked on


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Fig 5.0: Showing ceiling plan


Plate 4.0: Showing approach view


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Plate 5.0: Showing rear view


Plate 6.0: Showing left elevation


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Plate 7.0: Showing right elevation


Plate 8.0: Showing the building interior

Source: Author’s archive

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Plate 9.0: Showing the building interior


ANALYSES OF SOURCES OF EXTERNAL NOISE

External noise sources are devices or machineries located outside the building that

generates noise to the building. Sometimes, people talking frivolously outside the building

can also contribute to the production of the total external noise generated. In the building

surveyed, the major external noise sources are;

1. Vehicular noise: the noise produced from engines and exhausts of vehicles moving

around the building can be termed vehicular noise. The noise is often annoying and

can make people uncomfortable. Noises of very high decibel are also produced from

the horns of these vehicles

Plate 10.0: showing a moving vehicle Plate 11.0: Showing a generator

Source: Author’s archive (2014) Source: Author’s archive (2014)

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1. Generator noise: noises produced from generators are often termed generator noise.

In the building surveyed, the generator set was placed only about a metre away from

the building. The closeness of the generator to the building produces a very high level

of discomfort to the users of the building.

2. Air-Condition noise: The noise generated from the air-condition system is termed

air-condition noise. Noises from air-condition systems seems insignificant but when

the noise is measured it goes a long way. These noises are among the major external

noises of the building surveyed.

3. Human noise: Frivolous conversation among people outside the building can

constitute external noise. It was quite evident from the survey that people talking

carelessly at the top of their voice produces a high level noise that can cause

disturbance and make users of the building uncomfortable.

ANALYSES OF SOURCES OF INTERNAL NOISE

Internal noise sources are devices or machineries located inside the building that

generates noise within the building. Sometimes, people talking or murmuring inside the

building can also constitute to the production of the total internal noise generated. In the

building surveyed, the major internal noise sources are;

1. Fan noise: these are noises generated from the rotational movements of the fan

blade. At top speed the noise becomes quite evident and disturbing compared to

when the fan is at low speed.

2. Noise from office equipment: these are noise generated from computers, printers

and scanners. Although they do not produce high level noise but when they

become old and faulty they can produce high level noise.

3. Noise from air condition systems: these are noises produced from the air-

condition unit. They seem insignificant but when the air-condition unit becomes

old the noise they produce may become worrisome.

4. Human noise: People talking, murmuring and whispering within the building

may produce moderate amount of noise that may become unpleasant.

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Plate 12.0: showing a ceiling fan Plate 13.0: Showing an A/C unit

Source: Author’s archive (2014) Source: Author’s archive (2014)

ASSESSMENTS OF THE BUILDING ACOUSTIC CHARACTERISTICS

The acoustic characteristics of the building was assessed under the following

1. Reverberation: reverberation is the persistence of sound after its source has stopped.

(Source: lecture note series). The acoustic property of the building section surveyed

was very poor in relation to reverberation. The wall finishes have very poor acoustic

properties, the floor finish is hard and solid, and the ceiling tiles are not perforated.

The furniture used in the laboratory is made of hard woods which absorb very little

fractions of the total sound produced. When a speech is made in that section of the

building (computer science study laboratory one), it will take a long period of time

before the sound becomes inaudible even after its source has stopped.

2. Background noise: The noise produced from cars outside the building section, noise

from users of the space and noise from the air-condition unit makes up the

background noise. In the building section surveyed the background noise was quite

high. These is due to the presence of vehicular movement around the building and the

presence of air-condition unit in the space. Frequent whispering from users of the

space also contributed to the background noise.

3. Echoes: Due to the effect of reverberation, continuous sound was heard in the section

surveyed after its source has stopped. Echo is the sound that is heard after the sound

source becomes inaudible.

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MEASUREMENT OF EXTERNAL NOISE LEVELS

S/N Noise source Sound in dB

1 Vehicular noise 75-80dB

2 Human noise 55-60dB

3 Air – condition noise 55dB

4 Generator noise 75dB

Table 1.0: showing measurement of external noise level


MEASUREMENT OF INTERNAL NOISE LEVELS

S/N Noise Source Sound in dB

1 Air- condition 55dB

2 Fan noise 60-65dB

3 Conversation 50-55dB

4 Office/ Office equipment 45-50dB

5 Whispering 30-35dB

Table 2.0: showing measurement of internal noise level


METHODS OF IMPROVING THE ACOUSTICS OF THE BUILDING SPACE

SURVEYED

1. All faulty office equipment should be changed

2. All old office equipment should be replaced with new ones

3. All new appliances or equipments to be purchased must meet accepted noise

standards. Preferably, quiet appliances or equipment should be purchased.

4. Fan speed should be reduced at all times in order to reduce the noise level

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5. Frivolous conversation and arguments should be avoided within and outside the

building.

6. Thick carpets should be used as floor finish

7. Walls should be covered with thick curtains that can absorb noise

8. Soft perforated ceiling tiles should be used

9. The generator should be located at a reasonable distance from the building

10. Air –condition units should be cleaned and serviced at regular intervals. This is

because dust can cause friction and this may cause noise when in use

11. Shrubs should be planted to serve as a barrier against direct vehicular noise

12. The generator should be placed on a soft terrain in other to reduce vibration between

the generator and the concrete floor.

CONCLUSION

The space surveyed and the entire building has a very poor acoustic characteristics.

Architects should acquaint their clients with sustainable building materials with good

acoustic properties. Where necessary, architects should specify quality materials or

equipments that have good acoustic characteristics. Architects should indicate from the site

plan the exact placing of equipments so that equipment with the same noise level should be

placed together. Architects should also specify quality finishing materials with good acoustics

characteristics.

REFERENCE

1. “Lecture note series on acoustics”

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