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Sound Transmission Loss Analysis for Laminated Glass and Perspex
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
Sound Transmission Loss Analysis for Laminated Glass and
Perspex
W. H. Tan1,*, E. A. Lim2, E. M. Cheng1, K. S. Basaruddin1 and M. Hafifi Ramli1
1School of Mechatronic Engineering, Universiti Malaysia Perlis (UniMAP), Pauh
Putra Campus, 02600 Arau, Perlis, Malaysia.
2Institute of Engineering Mathematics, Universiti Malaysia Perlis (UniMAP), Pauh
Putra Campus, 02600 Arau, Perlis, Malaysia.
*whtan@unimap.edu.my
Abstract. The aim of this study is to analysis the sound transmission loss (STL) for the
laminated glass and Perspex. In this study, the STL of laminated glass and Perspex are
determined using the two-load transfer function method (TFM) impedance tube measurement
setup. There are 5 mm and 8 mm thickness of glass and Perspex were used. Glass and Perspex
will be laminated into double and triple layer in order to investigate its STL due to interlayer
effect. All the specimens are prepared into round shape with the diameter of 33 mm that fit
with the inner diameter of impedance tube. From the measurement, it is concluded that the STL
almost similar for the Perspex and glass without the layer lamination at the frequency range
below 3500Hz. Number of interlayer for the glass or Perspex lamination plays the major role
as main parameters that affect the overall STL.
1. Introduction
Nowadays, there are many noise problems happened in our workplace and surrounding, such as noises
come from busy traffic of transportation, industries machining, construction site and etc. that affecting
our daily life. To solve these problems, it is crucial to understand the knowledge of acoustic, noise
control and its prevention. Usually, to reduce noise level, it is compulsory to deal with frequency,
amplitude and wavelength of the sound. The sensitivity of human being on the sound frequency is
limited from 20 Hz to 20 KHz [1].
A laminated glass is the glass that consists of two or more layer of glasses with an interlayer
that typically made using ethylene-vinyl acetate (EVA) or polyvinyl butyral (PVB) in the middle of
the glasses [2]. Usually, laminated glass was used for automobile windshield, exterior store front,
window and wall for the building. Laminated glass is considered one type of safety glass in protecting
human from injuries as it can hold together when shattered. Thus, vehicle front windscreen normally
installed with laminated glass. The stress applies on the laminated glass could cause it to deform
elastically and demonstrate no plastic deformation before it fractures [3]. On the contrary, Perspex
2
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
flexibility is higher than the glass and therefore, it is able to withstand high speed wind and pressures
as it is used as building windows [4]. In general, Perspex was made using heating method, bending
and pressure forming [5].
In this study, the acoustic property of laminated glass and Perspex were analysed. The sound
transmission loss (STL) of the laminated glass and Perspex are measured using the two-load transfer
function method (TFM) impedance tube [6] [7].
2. Methodology
In this study, the impedance tube was fabricated using acrylic tube. The inner diameter of the tube is
33 mm with length of 1.25 m [8]. The detectable frequency range for the impedance tube is in between
60 Hz to 6000 Hz. The schematic drawing of the impedance tube is shown in Figure 1, and Figure 2
shows the fabricate impedance tube for this study.
Figure 1. Design for impedance tube CATIA V5. Figure 2. Fabricated impedance tube.
2.1. Specimen preparation
Table 1 listed the specimens that were used for the sound transmission loss (STL) measurement. There
are 5 mm and 8 mm thickness of glasses and Perspex were used. Glass and Perspex are laminated into
double and triple layer to investigate its STL via interlayer effect. All the specimens are prepared into
round shape with the diameter of 33 mm that fit tightly with the inner diameter of impedance tube. For
the laminated glass and Perspex specimen, the interlayer is seals using silicone SN 503 Silicon
Sealant. The veneer clipper tool is the jig that is used to control the thickness of interlayer for the
laminated glass and Perspex [10]. Figure 3–4 shows the prepared specimens that are used for the
measurement. The cross section layouts of specimens are showed in Figure 5–6.
Table 1. Material selection with thickness and interlayer.
Material
Thickness
5mm (single interlayer)
8mm (double interlayer)
Glass
Single
Single
Perspex
Single
Single
Laminated Glass
Double
Triple
Laminated Perspex
Double
Triple
Speaker Box
Second
Chamber
First
Chamb
er
Base
Mechanical
Coupling
Rigid Cap
Microphones
Holders
3
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
Figure 3. Perspex and laminated Perspex specimens. Figure 4. Glass and laminated glass specimens.
Figure 5. Double laminated layer with Figure 6. Triple laminated layer with
single interlayer (5mm thickness). double interlayers (8mm thickness)
2.2. Measurement setup
In this study, two-load transfer function method (TFM) impedance tube is used for the sound
transmission loss (STL) measurement. Figure 7 showed STL measurement setup in the laboratory. For
the measurement setup, the impedance tube required four microphones with each connected to the
Data Acquisition (DAQ), where the sensor signals are synchronised in post-processing and stored in a
computer where the measurement is done with two sensors simultaneously instead of one sensor in
two-times [11].The speaker was connected to the output port of DAQ, that provides random sinusoidal
noise signal generated by the DAQ using an analysis software known as LMS Test Lab 14A [12]. The
rigid cap is used as the rigid termination, while the sponge works as the anechoic termination for the
two-load TFM. All microphones were calibrated using microphone calibrator before the measurement.
The measurement data is collected and analysed via DAQ coupled with the installation of analysis
software in the computer. The STL measurement graph against frequency is then plotted [13].
Glass/ Perspex (2mm)
Interlayer (1mm)
Glass/ Perspex (2mm)
8mm, laminated
(double interlayer)
5mm, laminated
(Single interlayer)
8mm, original
5mm, original
8mm, original
5mm, original
5mm, laminated
(Single interlayer)
8mm, laminated
(double interlayer)
4
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
Figure 7. Setup of two-load transfer function method (TFM) impedance tube.
3. Result and discussion
In this section, the sound transmission loss (STL) measurement results are compared and discussed, in
term of specimen thickness, materials, and interlayer thickness.
3.1. Effect of specimen thickness on STL
The sound transmission loss (STL) for the glass with the thickness of 5mm and 8mm is shown in
Figure 8. The blue line indicates the STL of 5mm thick glass while the red line is 8mm thick glass.
From the result, it is discovered that STL of 5mm thick glass is always higher than 8mm thick glass
for the frequency range of 0Hz to 4500Hz. Overall, the STL of 5mm and 8mm thick glass are
relatively low, typically below 10dB for the frequency range below 3500Hz. Meanwhile, for the
frequency range 3500Hz and above, the STL shows much higher value for 5mm and 8mm glasses.
Similar observation is found for the Perspex with the thickness of 5mm and 8mm as shown in Figure
9.
Figure 8. Sound transmission loss for 5mm and 8mm thick glasses.
Speaker
Impedance tube
LMS Test Lab
14A
Data Acquisition
Microphones
Rigid Cap
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission
Loss (dB)
Frequency(Hz)
5mm Glass 8mm Glass
5
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
Figure 9. Sound transmission loss for 5mm and 8mm thick Perspex.
3.2. STL comparison between glass and Perspex
Figure 10 and 11 show the sound transmission loss (STL) comparison results for glass and Perspex
with thickness of 5mm and 8mm. Based on Figure 10, it is observed that STL of Perspex always
higher than glass with similar thickness of 5mm throughout the whole investigated frequency domain.
Similar trend is observed for the 8mm thick Perspex with frequency below 3500Hz as illustrated in
Figure 11. Hence, it is concluded that Perspex gives higher insulation than glass for same thickness
based on the obtained STL results in this study.
Figure 10. Sound transmission loss for Perspex and glass with thickness of 5mm.
Figure 11. Sound transmission loss for Perspex and glass with thickness of 8mm.
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission Loss
(dB)
Frequency (Hz)
5mm Perspex 5mm glass
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission
Loss (dB)
Frequency (Hz)
8mm glass 8mm perspex
6
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
3.3. Comparison of laminated layer with single and double interlayer on STL
Figure 12 and 13 shows the comparison sound transmission loss (STL) graph for laminated glass and
Perspex with single and double layers respectively. According to Figure 12, it is observed that STL for
laminated Perspex and glass is almost similar with small differences of STL for the frequency range
from 0Hz to 3500Hz. In contrary, when the interlayer increases to double layers, the STL is also
improved significantly compared with single interlayer. This phenomenon is proven in Figure 13 with
double interlayers. Simultaneously, it is also observed that laminated Perspex with double interlayers
obtained better STL throughout the investigated frequency domain in compares to laminated glass
with double interlayers. Therefore, it can be concluded that laminated Perspex with double interlayers
delivers higher STL as the interlayer is considered as an insulation material where it can absorb more
noise when the interlayer increases [14]. This phenomenon is proven in Figure 14 and 15, where the
comparison is done using similar thickness for laminated glass or Perspex, and the results shown the
laminated glass or Perspex is able to provide higher STL compared to non-laminated glass or Perspex.
Figure12. Sound transmission loss for laminated Perspex and glass with single interlayer (5mm
thickness).
Figure 13. Sound transmission loss for laminated Perspex and glass with double interlayers (8mm
thickness).
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission
Loss (dB)
Frequency (Hz)
8mm laminated glass 8mm laminated perspex
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission Loss
(dB)
Frequency (Hz)
5mm laminated perspex 5mm laminated glass
7
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
Figure 14. Sound transmission loss for 5mm thick glass and 5mm thick laminated glass with single
interlayer.
Figure 15. Sound transmission loss for 5mm thick Perspex and 5mm thick laminated Perspex with
single interlayer.
4. Conclusion
This study involves exploring, observing, and understanding the sound transmission loss (STL) for the
laminated glass and Perspex. From the STL results, it is concluded that the STL almost similar for the
Perspex and glass without the layer lamination. Simultaneously, one of the significant findings
observed in this study is when the interlayer increases for laminated Perspex or glass; the STL is also
increasing respectively. Thus, the number of interlayer for the glass or Perspex lamination plays the
major role in parameters that affect the overall STL.
Acknowledgement
The authors are grateful for the lab assistance, colleagues who are willing to share their opinion and
School of Mechatronic Engineering, Universiti Malaysia Perlis (UniMAP) for providing the
equipment and environment during this research.
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission Loss
(dB)
Frequency (Hz)
5mm Perspex 5mm laminated perspex
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Sound Transmission Loss
(dB)
Frequency (Hz)
5mm glass 5mm laminated glass
8
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International Conference on Advanced Manufacturing and Industry Applications IOP Publishing
IOP Conf. Series: Materials Science and Engineering 429 (2018) 012008 doi:10.1088/1757-899X/429/1/012008
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