Friday, June 19, 2009

Acoustic Report

1.0 Introduction
This report presents the study of acoustic quality and condition of a double-storey shop lot (My
Bookstore) at Seri Kembangan. The following gives an introduction to general purpose of study and also
gives an overall preview of this report.
1.1 General Purpose of Study
This report aims to analyze the acoustic quality and condition of a double-storey commercial
building and provide recommendation to improve acoustic quality and condition of the mentioned shop
The goal of this study is to improve acoustic quality and condition of My Bookstore by enhance
or preserve desire sounds otherwise reduce or eliminate noises.
1.2 Preview of Report
This report will showcase the different types of noise sources involved in the building. A set of
scaled drawing of the shop lot will be given together with the relevant plan, elevations and sections prior
to get a better analysis on how good acoustic quality can be achieved. It is because different space will
determine to enhance or to reduce the sounds.
After we venture into the building and data collection aspects, analysis will be produced to
evaluate the acoustic quality and condition of that shop lot. Problem of the acoustic qualities will be
discussed and then provide with recommendations to make sure acoustic perform better than initially
2.0 Methodology
Few steps were done to collect data about acoustic quality and the space. Firstly, recording site
inventory and noise sources was been done and followed by user analysis. Then we clarify the function or
activities in the bookstore which is classified as retail shop. According to Noise Rating (NR) Limits table
cited in Introductin to Architectural Science: The Basis of Sustainable Design, the maximum NR for a
Department stores is 40. In another words, interior of department store has a quiet environment in term of
noise. In addition, Szokolay (2004), the author of Introductin to Architectural Science: The Basis of
Sustainable Design stated NR40-45 is moderately noisy judged by majority.
(Table 1.0 Noise Rating (NR) Limits table cited by Szokolay, 2004)
Next, a full set of scaled drawings will be produce after the first site visit. Subsequently, furniture
analysis will be done. Then, materials of the interior finishes needed to be recorded for later analysis. Last
but not least, sound meter is been used to get readings of frequency of sound at the interior of book store.
2.1 Site Inventory
This section of the report introduces the site of the retail shop, site analysis, and also the building
2.1.1 Site Introduction
The shop lot that we chose is a retail shop which provides books, stationeries, and also household
items to the community in Seri Kembangan. Big range of group age people would visit the store from
small kids to senior citizens. Therefore good acoustic to achieve quite environment is important to ensure
the comfort for building users.
2.1.2 Site Analysis
In the macro site analysis, the site is located in a new piece of land in Seri Kembangan which
used as commercial land. While for the micro site analysis, “My Bookstore” has limited opening, which is
at the front facing the parking and road. The open space at the front has little obstruction for the entering
of day light.
(Figure 2.1 Location Map)
(Figure 2.2 Site Plan)
Blue Coloured Area is the location of “My Bookstore” while the pink coloured area is the
neighboring building mass. White Colour zone is the empty space.
2.2 User Analysis
During analysis, the occupants for visiting the book store mostly are children with parents,
students and readers. The group age of visitors is big range from children to senior citizens. It is important
that the occupants or users satisfied with the environment that they were in. Hence, it is important to make
sure the noise should be minimized or eliminated for the comfort of customer. As stated by the shop
Manager, Mr. Lai (2007) the key to be success in business is to make customer stay longer in the shop.
Therefore, a quite environment is one of the key aspect to make customer stay longer in the shop.
2.3 Scaled Drawings
Scale Drawings method help to record the lighting layout and zoning. This is a very important
step to clarify the function of the zone and the layout of lighting. Besides, from the scaled plan, grid lines
are drawn 2m by 2m for recording lux meter reading at the next step.
As shown in Figure 2.1, down lighting system were used at Zone B and C at the Ground Floor,
spacing each other 2m by 2m. As shown in Figure 2.1 Working Plane is defined as 1.0 m from the floor,
and the height of the lighting is at ceiling level (2700 from floor).
(Figure 2.3 Ground Floor Plan)
(Figure 2.4 First Floor Plan)
(Figure 2.5 Section A-A)
(Figure 2.6 Section B-B)
2.4 Materials and Furniture Analysis
(Figure 2.7 Ground Floor Ceilings finished with concrete)
Zone A ground floor ceilings are finished from concrete and reflect much noise compare to
gypsum boards finished ceilings.
( Figure 2.8 Ground Floor Ceilings finished with plaster)
Zone B and C ground floor ceilings are plastered which are not reflecting so much noise and at
the same time it also absorbs as part of it.
( Figure 2.9 Wood bookshelves)
Furniture such as bookshelves is made from wood. This material helps to absorb certain sound
waves when exposed to noise.
( Figure 2.10 Arrangement of furniture)
The uneven and arrangement of furniture in the bookstore can break down certain sound waves.
Materials of bookshelves helps to prevent reflect of sound.
2.5 Interior Finishes
(Figure 2.11 Ground Floor Plan-Materials Indication)
(Figure 2.12 First Floor Plan-Materials Indication)
(Figure 2.13 Section A-A -Materials Indication)
2.5.1 Reverberation
Reverberation is the persistence of sound after the sound source has ceased. Such persistence is a
result of repeated reflections in an enclosed space. (For spaces of unusual shapes, Beranek 1988.) A space
with highly reflective surfaces, therefore a low average absorption is coefficient.
Since room absorptions is related to total surface area, which turn is related by room proportions
to room volume. The bookstore we analyze shows that the space or shapes in the room is uneven. It is
arrange with different kind of furniture. Therefore the sound reflectance in the room is low.
Reverberation can be considered as mixture of previous and more recent sounds. The converse of
reverberation or reverberance is articulation.
(Figure 2.14 Chart indicating liveliness of a room. Stein, Reynolds ,Grondzik ,Kwok 2006)
Reverberation Time for Zone A (Refer to plan)
Dimension for Zone A = 18m x 8m x 2.7m
Absorption, A= Area x Absorption Coefficient
Surface/ Finishes Area (ft2)
Absorption Coefficient
Brick wall with plaster finish 419.79 0.03
Glass Panel 86.43 0.03
Marble Flooring 1550.00 0.01
RC ceiling 1550.00 0.015
People 53.81 0.46
Wall Absorption = 419.79 x 0.03
= 12.59 Hz ft2
Glass Panel Absorption = 86.43 x 0.03
= 2.59Hz ft2
Marble Flooring Absorption = 1550.00 x 0.01
= 15.50 Hz ft2
RC Ceiling Absorption = 1550.00 x 0.015
= 23.25 Hz ft2
People = 53.81 x 0.46
= 24.75 Hz ft2
Total Absorption = 12.59 + 2.59 + 15.50 + 23.25 + 24.75
= 78.68 Hz ft2
Sabin, A = Total Absorption / 10.76
= 7.31
Conclusion: Sabin is exceeding 1 which means the room is totally dead in term of echo. However, this
is a good condition for a department store like “My Bookstore”. In another words, “My Bookstore” does
not have the problem of echo.
2.5.2 Mechanics and Absorptions
Absorptive materials are also an acoustic phenomenon so that we may understand the absorption
in appropriate. In an untreated room of normal construction, when the sound waves strike the wall or
ceiling, small portion of sound is transmitted and small portion is absorbed. Most of it is reflected.
When acoustical treatment is applied to the room surfaces, some of the energy in the sound waves
is dissipated before the sound reaches the wall. The transmitted portion is slightly reduced, but the
reflection is very much reduced.
It is important to understand that the principal effect of absorptive material on reflected sound.
The transmitted sound energy is essentially determined by the mass of the solid airtight barrier between
the two spaces.
(Table 2.0 Octave Band Average Sound Absorption Coeeficients)
2.6 Sound Meter
(Figure 2.15 Sound Level Meter, RS-232/ Data logger)
The need for a means of measuring sound level in this projects is to confirm that the designs
criteria of a shop have been met the requirement or obvious. Sound level meter is an instrument to show a
relationship meter readings with subjective loudness impressions, most such instrument that provide a
single –number output are furnished with weighting networks.
As results, networks weighting curves are used today for all the measurement, regardless of
loudness. All measurements should be identified with the weighting network used, such as 50dBA or 100
dBC(Stein et al. 2006, p. 746).
More accurate measurements of complex sounds than are possible with standard sound level
meter are made with sophisticated instruments that measure intensity in octave bands.
The readings are recorded during the business hours of the bookstore, which is 10am, 2pm, and
8pm. The sound level is measured at every 2 meters at the interior of the bookstore. The readings are
recorded in dBa unit and later converted it into db unit. Later on, calculation will be done in order to get
the sound level in the particular space.
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3.1.2 External Noise Sources
Mostly the sound or noise generated within the surrounding people at the pedestrian and the
vehicle flow density do generate noise. Besides that, the shop is also located very near to a restaurant.
When it is a peak hour, there will be a lot of customers dine in the restaurant which will create a lot of
noise. The exterior noise is the main generated sound. Thus, there is a need to solve these problems.
(Figure 3.4 Noise sources from pedestrian)
(Figure 3.5 Noise Sources from pedestrian, vehicles and restaurant at 10.00 am)
The external noise sources have the same condition at in the morning, noon and evening.
Therefore, the readings of Sound Meter are expected to have no much different in these 3 times.
3.2 Data Collection
The data shows that noise rating level in “MyBookstore” is consistent all the time. Besides, the
average of noise rating level in “MyBookstore” is 59.4dB which is 19.4 dB higher than acceptable level
(40.0dB for department store) as stated by Szokolay (2004). The sounds level is calculated by using this
Analysis of Data
(Graph 3.0 Noise Rating Level at Ground Floor and First Floor)
Note: Sound Level Calculation refer to Appendix A
The graph indicates Noise Rating Level at Ground Floor is slightly higher than the Noise Rating
level at First Floor. This can be explained that Ground Floor has a nearer contact to the external noise
sources which are the vehicles and pedestrian at the street frontage. However, the different of average
Noise Rating Level between Ground Floor and First Floor is only 2.9dB. In another words, the
environment at ground floor and first floor both are rated as Noisy.
(Figure 3.6 Noisiness judged by majority. Szokolay. 2004. p.154)
(Figure 3.7 Noise Rating data in Section.)
3.2.1 Ground Floor
The diagram shows that the db near the entrance has got the highest reading as expected. The
entrance is not closed and it’s facing the main road where noise sources from the vehicles and pedestrian
will contribute uncomfortable noise into the bookstore. There is also a fan coil unit located right above the
entrance. Therefore, it increases the noise level at the entrance. As it goes deeper inside the store, the db
decreases evenly and consistent as the noise is filtered and reflected by the furniture around it.
3.2.2 First Floor
There are no wide openings at the first floor that could let unwanted noise entering the building.
However, the highest db which had recorded is at 3 points of the diagram which has the reading of 62.9
db, 57.9 db, and also 61.5 db. It got higher db is because there are 3 fan coil units located on top of each
point which contribute some noise. As for other area, its consistent as its filtered by the surrounding
4.0 Conclusion
After Analyzed the data collected, this section will be concluding the Strengths and Weakness
(problems) of the existing acoustic condition at “My Bookstore”. “My Bookstore’ is rated as Noisy
referring to Szokolay (2004).
To achieve the comfort environment for a department store, the sound level of existing which is
59dB must bring down to 40dB. (Szokolay 2004)
After understanding that most of the noise sources come from the external, the strategy to reduce
sound level to desire level (40dB) is to insulate or reduce the transmission of noise from the outdoor.
From the data, we also found out that sound level at the frontage of the shop is the highest while point
which far from the frontage is lowest.
4.1 External Noise Sources
The major sources of noise are coming from the external. These noise sources are pedestrian and
vehicles. Vehicles are contributing more noise than pedestrian do. Besides, from the data we get from
sound meter, we found that there are only very little reduction of sounds when it travels into the building.
This can be explaining that the glass door is always opened and the thickness of the glass might be too
thin to reduce the transmission of sounds into the building.
4.2 Internal Noise Sources
Internal Noise Sources have little impact to the noisy environment in the bookstore. The internal
Noise Sources are for example radio and cashier that is caused by human behavior that we cannot control
of. Therefore we suggest to reduce the internal sound level by using high sounds absorbance materials.
5.0 Recommendation
To achieve the goal of acceptable and suitable sound level, below are the
recommendations to improve the acoustic in the retail shop.
5.1 Furniture comment and propose
(Figure 5.1 Bookstore furniture)
Furniture that use by the bookstore is constructed by wood, therefore there will be able to reduce
sound waves travel in the room. Besides that, an uneven arrangement of furniture does affect the sounds
travel or reflectance of noise. The plastered ceiling also has the function of absorb certain noise. Furniture
of the bookstore does not need much changing in this situation.
(Figure 5.2 Section Cut Zone C - Reverberation of noise in room)
5.2 Materials Comment and Propose
(Figure 5.3 Zone A Existing) (Figure 5.4 Zone A New Proposed)
As shown at the picture above, recommended that the ground floor should be added Gypsum
board ceiling with a good absorbance. This could reduce reflection of sound at the interior. Besides that,
double glazing glass should be integrated along the glass panel at the entrance. This could help to reduce
noise from the exterior and could adding aesthetic value to the bookstore.
5.3 Current Situation
(Figure 5.5 Section of existing glass design)
(Figure 5.6 Section of new integrated design with double glazing glass)
(Figure 5.7 Section of existing ceiling finished)
(Figure 5.8 Section of proposed ceiling with gypsum board ceiling panel)
5.4 Plant trees as sound barrier
Trees will be planted at the exterior of the bookstore along the entrance. These trees act as a sound barrier
and help to absorb the sound level generated by the vehicles from the main road. As the sound wave
passes by the plantation, the noise eventually will be filtered and the sound level which enters the
bookstore will be decreased. Besides that, planting trees may help to beautify the bookstore environment.
(Figure 5.9 Section of building with trees planted)
(Figure 5.10 Arrangement of trees along the entrance)
Reference List
Stein B, Reynolds JS, Grondzik WT, Kwok AG, Mechanical and Electrical Equipment for
Building (Tenth Edition) 2006, John Wiley & Sons, Inc.
Szokolay S. V, Introduction to Architectural Science: The Basis of Sustainable Design. 2004,
Architectural Press.

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