ACOUSTIC ANALYSIS

OF

SEN. (DR) BUBAR ABBA IBRAHIM

LECTURE COMPLEX

COMPILED

BY

BABATOLA O.O. ARC/10/1116

ILESANMI L. A. ARC/10/1130

SUBMITTED TO

THE DEPARTMENT OF ARCHITECTURE

FEDERAL UNIVERSITY OF TECHNOLOGY,

AKURE, ONDO-STATE

LECTURER-IN-CHARGE

PROF O.O. OGUNSOTE

ARC GANIYU

July, 2014

INTRODUCTION

The term acoustics can be defined as the science of sound control with consideration to the

interior and exterior components and features of a building.

The primary means of communication in most educational settings are speech and listening. The

acoustics of the lecture room can support the speaker by improving the level and the

intelligibility of speech – or the opposite. The room acoustics in lecture rooms is therefore an

important issue when considering the productivity and working environment in schools and other

teaching situations

The presence of electronics and computer has immensely increased our measuring ability with

great accuracy. Analyzing techniques that could have only been put to use about years back are

now common-place. However, the inadequacy of analyzing capability in the past has led to a

particular architectural quality of buildings and rooms that are poor acoustically in relation to

their intended purposes. The shape, construction type and dimension and the content of a room

will determine the rate of sound transmission, sound reflection and absorption in such enclosed

space.

DESCRIPTION

The lecture room is partitioned into three different lecture spaces using plywood and each lecture

rooms are essential spaces for communication considering the acoustic attribute of the spaces.

Architecturally, the importance is based on sufficient audibility of the space.

The acoustic nature of a lecture room, being an enclosed room where lectures, seminars and

even defense are held, can also result in disturbance and acoustical challenge.

A lecture room is more efficient when the sound from inner and outer part of the space is

minimal. To and fro movement of people around the building is a typical source of external noise

to the building which will result in distraction or disruption of full concentration on the ongoing

activity.

The lecture room to be analyzed is located beside and behind the 2 in 1 lecture theatre and the

School of Earth and Mineral Science respectively at Obanla campus of the Federal University of

Technology, Akure.

The selected lecture room has a rectangular shape with the one on the left facing the parking lot

directly while the other wing on the right is facing the walkway from the SEMS building to the

extension building.

COMPONENTS OF THE LECTURE ROOM:-

i. Aluminum window frame with sliding glass sash window

ii. 225mm thick Sandcrete hollow block walls rendered with cement and sand

mix, painted with whitish-yellow emulsion paint.

iii. Asbestos ceiling sheets etc.

iv. Steel panel double swing door

v. Polished ceramic tile floor finish

Pictures showing the steel panel door

picture showing the aluminum frame with sliding glass sash window

Pictures showing the polished ceramic tile floor finish

Picture showing the asbestos ceiling sheets etc.

EXTERIOR ELEVATION OF THE SELECTED SPACE

Picture showing the approach view of the selected space

Picture showing the left approach the building

INTERIOR ELEVATIONS OF THE SELECTED SPACE

Pictures showing the right and left view of the selected space in the building

Pic

Picture showing the front and back view of the selected space in the building

ACOUSTIC ANALYSIS OF SEN (DR) BUBAR ABBA IBRAHIM

LECTUREROOM

Firstly it is necessary to identify the acoustic problems of the above space. The problems can

be perceived in two ways external and internal.

.EXTERNAL ACOUSTIC PROBLEMS

The table below show the sources of noise in relation, the original noise level from the near

field in decibel barrier impact and the noise level of reverberant field which is the lecture

room, the building encounter some acoustic challenges which is as a result of the following:

I .Its location, surrounding

II. Features and

III. Human activities e.g. sound from the students and staff passing by and also noise from

the car park (vehicular movement which serves as source of external noise to the lecture

Vehicular noise: Vehicular movement from the car park is one of the major sources of

external noise to the building.

Human activities: activities from the adjacent buildings serves as a source of external noise

to either wings of the building and also another source of noise is from the to and fro

movement of students and staffs, their footsteps sound, background noise is also a primary

source of external noise to the building. The diagram below shows the impact of external

noise on the occupant of the building

Site plan showing the noise source

Floor plan of the selected space

Walkways which is the major source human external noise

SECTION X-X OF SEN (DR) BUBAR ABBA LECTURE ROOM

Picture showing the car park where the vehicular noises come from

INTERNAL ACOUSTIC PROBLEMS

The dimension, finishes and shape are the interior properties that determine the sound reflection

or absorption rate of the space. Background noise from students within each lecture spaces of the

building and also noise from movement of furniture within room is also a problem of internal

perception of noise. The following are the content of the lecture room and how they affect the

acoustic of the space.

i. Walls: The wall is 225 mm thick rendered and finished with a whitish-yellow paint, it

will b just a little bit effect in reduction of the noise

ii. Openings: The windows are 2100mmx 1200mm which make it easier for th

penetration of noise into the building and also the door is a 1800mmx2100mm steel

framed door. Which also contribute to the noise within when opened of closed,

therefore the entrance of a student of staff during a lecture will result in distraction or

a break in the lecture

iii. Floor finish: Floor finish as stated earlier is a polished ceramic tile floor finish which

will only contribute to the poor acoustics of the building through the sound it makes from

footsteps of a student or staff in motion within the selected space

iv. Furniture and fittings: The furniture in the space are combination of wood and steel

and therefore can a source of internal noise.

v. Ceiling: the Ceiling is asbestos and therefore has no contribution in the reduction of

the noise. There are ceiling fans hung to the ceiling which are also sources of internal

noise

A PERCEPTUAL ASSESSMENT OF THE ACOUSTIC CHARACTERISTICS

OF THE SELECTED SPACE

We shall describe the characteristics of the space acoustically under the headings

below which are:

I. The Background noise

II. Reverberation and Echoes

Background Noise

vi. The Background noise has been reduced to a reasonable extent, with the use of fins

at the windows at interval of3 meters it also serve as a shading device for the space

and also dampen the intensity of the sounds coming from external sources

vii. The quick elimination of unnecessary external activities like chatting, wondering

during working hours is still achievable.

viii. From car park, and noise from adjoining building, like the SEMS building and

extension, walkways that link them, and the 2in 1 to create an conducive learning

environment.

Reverberations and Echoes

ix. The interiors space is such that each listener has its auditory line of perception. Even

if the walls surfaces are smooth and there is possibility of reflection, and also the

reverberation time is such that speech is intelligent in the building.

x. The materials used in the interior space are not very inclined acoustically.

xi. However, due to the size of the space, It is worthy of note that echoes aren’t usually

experienced.

PROPOSAL FOR ACOUSTIC IMPROVEMENT OF SEN. (DR) BUBAR ABBA

LECTURE ROOM

The acoustics condition of a selected lecture space in the Sen. (DR) Bubar Abba Ibrahim lecture

theatre as been analyzed showing the materials and their acoustic value and attributes and we

also pointed out both the external and internal noise source to the selected space

Screening:

With the use of Absorbent materials and surfaces, external noise reduction will be achieved,

There are examples and types of absorbent materials;

i. Porous absorbents (best for high frequencies)

ii. Membrane absorbents (best for low frequencies)

iii. Resonant absorbers (resonators)

i. Installation of Carpet on the Floor

Noise from impacts such as shifting furniture and footsteps are less in rooms with carpet floor

finish compared to rooms with floor tiles finish. Carpets however raise questions on indoor air

quality and high maintenance costs which must be balanced with acoustical benefits.

ii. Use of a Sound System

The use of sound system like the wireless microphone used by the teacher to pick up his voice,

the voice is then amplified and played through a loudspeakers strategically positioned in the

room to enhance speech sounds for the students within the space, this prevents the lecturer from

stressing his or herself to achieve audibility.

iii. Installation of padded furniture

Installation of foam padded and leather finished chairs will help in absorption of some sound.

iv. Installation of double glazed windows

With the size of the window, the best way to achieve noise reduction in that aspect is the through

the installation of double glazed window

4.1 PROPOSAL FOR REDUCTION OF EXTERNAL NOISE

Screening of Building

The noise coming from the surrounding walkways and car park can be screened-off using a using

a transparent insulating material that will not disturb light ray and also trees and shrubs can be

planted to reduce the noise coming from the car park.

Insulation

This will be most effective in the fenestration area of the building with the use of double glass windows

Which reduce noise penetration and also the use of aluminum famed door will be effective in noise

reduction..

Generation of noise reduction laws

Nose reduction laws can be implemented for students and staff movement should be restricted to some

specific areas during working hours.

CONCLUSION

The most importance attribute of a lecture room is for the lecturer or speaker to pass information

to the listeners or audience with ease .considering the acoustic level of the selected portion of the

Sen. (Dr) Bubar Abba Ibrahim Lecture theatre to an extent is conducive considering the position,

but with the above proposal, an acoustic improvement can be achieved.

.

REFERENCE

Professor Olu OlaOgunsote. (2007) Acoustics and Noise Control Lecture notes, 2007

Acoustical Society of America, ASA (2000) ‘Classroom acoustics. A resource for creating learning environments with

desirable listening environment with desirable listening conditions’. 2

Huntington Quadrangle Melville,Ny11747

Jullien J. (August4-6,1986) Measurements of room acoustic quality, The