Download GRPOUP 26

Acoustic analysis report of new senate
chamber, federal university of
technology Akure.
Compiled by
Group 26
Obayanju Oluwapelumi
arc/09/7397
Ogidan olayinka Daniel
arc/09/7402
Submitted to
the department of architecture
federal university of technology akure,Nigeria.
Lecturers in charge
Prof. o .o ogunsote
July,2014
TABLES OF CONTENTS
1.0 INTRODUCTION
1.1 Description of the building
1.2 Finishes
2.0 ARCHITECTURAL DRAWINGS
2.1 The site plan showing the building and sources of noise
2.2 The floor plan of the main hall showing furniture, materials, finishes
2.3 The ceiling plan of the main hall
2.4 Pictures of the senate chamber
3.0 ANALYSIS OF THE SOURCES OF INTERNAL AND EXTERNAL NOISES
3.1 Sources of internal noises
3.2 Sources of external noises
4.0 ASSESSMENT OF THE ACOUSTICAL CHARACTERISTICS OF THE
SENATE CHAMBER
4.1Reverberation
4.2 Background noise
4.3 Loudness of original sound
4.4 Measurement of internal and external noise levels
5.0 PROPOSAL FOR AMELIORATING THE INTERNAL AND EXTERNAL
NOISE SOURCES.
5.1 Proposal for internal noise control
5.2 Proposal for external noise control
6.0 CONCLUSION
7.0 REFERENCES
1.0
INTRODUCTION
Acoustics can be said to be the science of sound i.e. the way in which a room or theatre is
designed in terms of its shape, construction, finishing materials, etc. that make it good or bad for
carrying sound.
Noise is defined as unwanted or damaging sound, that is, sound which interferes with what
people are trying to do, or sound which has an adverse effect on human health or safety.
The senate chamber which is located in the new senate extension building is the building under
analysis in this paper, and this will be analyzed stating the effect of the design – shape, size,
construction materials, location, and other determinant factors – on the overall perception of
sound within the internal space.
The sources of noise interfering with the activities within the building are also identified and
analyzed exclusively.
The solutions proposed for the building is guaranteed to reduce the noise level within the
building to an appreciable level that will provide a more conducive learning environment for the
users of the LT.
1.1
DESCRIPTION OF THE SPACE.
The senate chamber is an hall purposely meant for deliberating of legislative, judicial body and
executive and academic matters of the university.
The following highlights its description:

LOCATION: The New Senate Extension Building, Obanla.

SEATING CAPACITY: 80 seater

FLOOR AREA: 225 SQM

SPACE HIGHLIGHTS: The space is a square shaped hall constructed in a stepped form
as to allow for proper visibility and sound movement, also well ventilated and lighted
with high and low level window.
The seating arrangement is permanent with no room for movement with three seats per
row.
1.2 FINISHES

FLOOR FINISHES: The floor finish is made of vitrified floor tile finish of grey colour
of approximate thickness 6mm.the podium is made of concrete floor also with same tile
finish but of height 450 mm.
PLATE 1: Showing Vitrified Floor Tiles

WALL FINISH: The wall are of 225mm hollow sandcrete block plastered with 10mm
thick mortar and finished with butter color texcoat paint .
PLATE 2 : Showing The Texcoat Wall Finish

CEILING: The ceiling is finished with white pvc ceiling strips of 3000mm x 100mm x
5mm
PLATE 3: Showing The Polyvinyl Chloride(PVC) Ceiling Finish.
2.0
ARCHITECTURAL DRAWINGS.
FIGURE 1: Site Plan Showing The Sources Of External Noise
FIGURE 2 : Floor Plan Showing The Seating Arrangement,Floor Finish And Source Of
Background Noise.
FIGURE 3 :Ceiling Plan Showing The Lighting Points And Pvc Ceiling
INTERIOR VIEWS OF THE SENATE CHAMBER.
3.0
ANALYSIS OF INTERNAL AND EXTERNAL NOISE.
3.1
INTERNAL NOISE.
Quietness is more than an important factor especially in areas such as the senate chamber as it is
the prerequisite for good listening. There are a number of ways that noise intrudes into the
auditorium. The quietness of an interior space is degraded when outside noise gets inside,
soundproofing helps. The quiet is also degraded by internal noise sources, quiet air conditioning
helps. The quiet is affected when sound from the loudspeaker reverberates too long, sound
absorption helps.
Whenever the auditorium is not quiet, people will not understand what is being said. Thus, the analysis
of the sources of internal and external noises is illustrated below.
The internal noise are generated within the senate chamber and this in a way affects the intelligibility of
speech within the space
3.2 SOURCES OF INTERNAL NOISE:
These are the noise generated from within the space and that which is capable of reducing speech
intelligibility, they are as follows;

Appliances: This includes the electrical fittings within the space and this includes air
conditioners, fan and speaker.

Voice: this is the main source of internal noise. It comes from the verbal discussion of the
audience in general.

Movement: impact sounds are made from falling objects and dragging of feet or seats on
the hard terrazzo floor.

Surface reflection of direct sound: Furniture with smooth and reflective surface reflect
direct sound causing reverberation. The terrazzo floor also contributes to this.
3.2 SOURCES OF EXTERNAL NOISES
External noise is those generated around from outside the space and that which is capable of
causing distraction and disruption of activities and proceedings within the senate chamber.
The major sources of external noise are:

Car park: it is a very noisy source during the day. Noise is generated by moving cars
trying to park, or cars going out of the area.
 Adjoining roads: the adjoining roads around the senate extension building are also
sources of noise to the chamber as it is situated close to the road in terms of its external
walls.
 Adjoining offices: these are also other sources of background noise into the senate
chamber, as the noise generated from these office spaces is capable of disturbing activities
in the chamber.
4.0 ASSESSMENT OF THE ACOUSTICAL CHARACTERISTICS OF THE SENATE
CHAMBER
The senate chamber is a room intended for listening to speech, administrative, academic and
judicial meetings. Hence in the intelligibility of speech is of utmost importance and this can be
analyzed considering the following factors which includes reverberation, background noise,
loudness of the original sound, and the size and shape of the auditorium.
4.1 REVERBERATION
Reverberation simply refers to the persistence of sound in an enclosed space as a result of the
repeated reflection or scattering after which the noise source has stopped.
The total absorption in a room is found by adding the absorption of the surfaces, the seats and the
audience. The ideal reverberation time for speech is about 1 second and the maximum acceptable
time is about 2 seconds. The reverberation time for music should be between 1 and 2 seconds.
for most normal rooms
Therefore in relation to the space under analysis, this is the kind of sound that begins to be felt
starting about ¼ second after the direct signal passes by and lasts out some 2 to more 5 seconds. It
is the rounds of sound in the room that slowly dies out and it is the very last thing we hear of a
sound before the hall finally falls silent. Reverberation is not a series of echoes, it is much more
chaotic. There are no distinct time sequences for the sounds that make up reverberation. There are
some curious features however within a reverberant field. Reverberation within the senate chamber
is very minimal due to the use of upholstery seat which are good in sound absorption
4.2 BACKGROUND NOISE
This is the normal prevailing ambient noise from many sources including street traffic and outdoor
noises in general. Other sources include air conditioning equipment, structure-borne noise from
mechanical equipment, noise from adjoining rooms and noise from the audience
itself. Such background noise may reduce speech intelligibility and cause serious distraction in
listening to speech. When such noise is present, the loudness of the original sound must be increased
to overcome the effects of interference. The background noise may also be reduced at source. These
sources, both internal and external should be studied and proper remedial measures taken. Hence in
relation to the senate chamber, the major source of background noise are the adjoining roads(internal
lobby around the chamber inclusive),and this pose a challenge as regarding the speech intelligibility
within the chamber as it is capable of interfering into proceedings within the space.
PLATE 4: Showing The Adjoining Lobby Around The Senate Chamber Which Is A Source Of
Background Noise.
4.3 LOUDNESS OF ORIGINAL SOUND
Intelligibility of speech increases with loudness; in large rooms it is often necessary to use public
address systems for amplification. In this distortion of speech by the equipment should be
avoided, hence the use of public address system in the senate chamber is in place as to amplify
the loudness level of the original sound and thereby increasing sound intelligibility.
PLATE 5: Showing Table Stand Microphones.
PLATE6 : Showing The Wall Mounted Loudspeaker
4.4 MEASUREMENT OF INTERNAL AND EXTERNAL NOISE LEVELS
The external and internal noise level is measured with THE DECIBEL SCALE, and the readings
recorded are as follows,

INTERNAL NOISE LEVEL - 44 dB

EXTERNAL NOISE LEVEL – 60dB
In relation to the specified standard noise level of areas such as courtroom, conference room and
auditorium which is between 40 -45 dB, hence the noise level of the senate chamber is still within
range. Also for the external noise level which is 60dB in comparison to the standard noise level of
55 – 60 dB is at the peak of the range.
5.0 PROPOSAL FOR IMPROVING THE ACOUSTICS OF THE SPACE BY
AMELIORATING INTERNAL AND EXTERNAL NOISE.
The proposal for the improvement of the acoustic of the senate chamber is as follows:
5.1 PROPOSAL FOR INTERNAL NOISE CONTROL.

CEILING:
as to enhance the
acoustic
level
chamber
the
of
the
ceilings
senate
should
constructed from or covered by
some form of sound absorbing,
acoustic ceiling tile or
mineral tile which conform
to
the code (NRC > 0.90).

FURNITURE: instead of shining and reflective surface furniture (tables), sound
absorbing surfaces should be used

WINDOWS: use of window panels with sound proof glazing should be used instead of
the conventional sliding and casement window

LIGHT FITTINGS: Flat Lucite/Perspex lenses over fluorescent tubes are
the worst fittings for sound reflection; parabolic, deep cell diffusers are the best for sound
absorption.

FLOOR: Instead of the use of normal floor tiles, acoustic floor tile or carpet(rug) should
be used as to increase the NRC, but only up to about 0.3 because Moving to thicker floor
carpet or rug or acoustic floor tiles will reduce impact noise

WALL : In contrast to the conventional emulsion or texcoat wall paint finish the use of
water based flat latex paint should be used for the wall surface finish also wall carpeting
will increase
sound absorption, as does placing cork tiles/corkboard on the walls. (However, the NRC
for these surfaces is still 0.2 - 0.3.)
5.2 EXTERNAL NOISE CONTROL.

BUILDING DESIGN
The functional layout should have been such that the senate chamber should have been located at the
far western end of the site which is away from the adjoining roads which are the major source of the
background noise.

INSULATION
The use of soung insulating material within the exrenal walls and opening can also reduce the
external noise
6.0 CONCLUSION
An acoustically healthy environment cannot be overemphasized. The spatial
requirements, construction materials, site selection, and design and amplification systems for
large halls are important for consideration.
It should be noted that the noise source, its transmission path, and the receiver are the three basic
acoustical situations that help in noise control.
Hence, the students have grabbed an ample knowledge of architectural acoustics which will
definitely help them in appreciating and applying such knowledge in their designs.
7.0 REFERENCES
Ogunsote ,O.O Introduction to Building Climatology - Chapter 8 – Acoustics/lecture notes
Room and Auditorium Acoustics /lecture notes