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 INTRODUCTION1.1 Description of the building1.2 Finishes

2.0 ARCHITECTURAL DRAWINGS2.1 The site plan showing the building and sources of noise2.2 The floor plan of the main hall showing furniture, materials, finishes2.3 The ceiling plan of the main hall2.4 Pictures of the senate chamber

3.0 ANALYSIS OF THE SOURCES OF INTERNAL AND EXTERNAL NOISES 3.1 Sources of internal noises3.2 Sources of external noises

4.0 ASSESSMENT OF THE ACOUSTICAL CHARACTERISTICS OF THE SENATE CHAMBER

4.1Reverberation4.2 Background noise4.3 Loudness of original sound4.4 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 theaudience. 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 publicaddress systems for amplification. In this distortion of speech by the equipment should beavoided, 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 of the senate chamber the ceilings 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 arethe worst fittings for sound reflection; parabolic, deep cell diffusers are the best for soundabsorption.

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 NRCfor 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