Field of the invention
The present invention relates Eichhornia crassipes (Water hyacinth) whole plant or part
as sound proofing material. More particularly, the present invention relates to a system
comprising filing of whole part or petioles of Eichhornia crassipes between two walls to
provide sound proofing.
Background of the invention
Undesirable and potentially hazardous noise is a by-product of mechanised means of
transport, heavy industry and other technologies aiming at achieving high speeds. The
environmental impact of noise is becoming a matter of increasing concern, and
considerable efforts are required to find effective means of noise. Studies have been
conducted on Dendrobium candidum and found that sound wave affects the activity of
antioxidative enzymes and lipid peroxidation in different plant organs as well. Since
noise may be lethal at higher decibel levels, a healthy living warrants reducing sound
levels employing sound proofing, a technique in which acoustic materials are used to
attenuate, deaden, or control sound and noise from machinery and other sources of
environmental pollution to bring the levels within limits required for regulatory
compliance. Soundproofing achieves noise control in two different ways viz. noise
reduction and noise absorption. Noise reduction simply blocks the passage of sound
waves through the use of distance, and intervening objects in the path of sound. Noise
absorption operates by transforming the sound waves by suppressing echoes,
reverberation, resonance and reflection. The dampening characteristics of the materials
are important in noise absorption. Sound-absorbing materials are added to the surfaces
in different directions, such as in ceiling and walls, so as to trap the noise, as it ricochets
from surface to surface and back to the occupants. Different types of man-made
materials such as glasswool, acoustic foam, acoustic insulation panels, noise stop
barrier foam, noise reduction blankets and sound curtain systems used for sound
proofing demand high cost inputs, and are not environment friendly.
Thus, there arises a need to develop a system which comprises use of plant materials
for sound proofing would be a cost effective and eco-friendly approach.
2
Objects of the invention
The main object of the present invention is to provide an eco-friendly material for sound
proofing other than man-made materials.
Yet another object of the present invention is to provide an apparatus comprising whole
plant or plant parts of Eichhornia crassipes, between walls of apparatus.
Another object of the present invention is to provide an apparatus wherein plant parts of
Eichhornia crassipes is petioles.
Another object of the present invention is to provide an apparatus wherein whole plant
or plant parts are filled with a density of 0.026 g cm-3.
Description of drawings:
Figure 1: Apparatus for study of soundproofing comprising Eichhornia crassipes.
Detailed Description
Present invention provides an apparatus with filling of whole plant or plant parts of
Eichhornia crassipes plants.
Plants used for the present study were collected from Keshopur wetland (32˚4’22.17”N,
75˚22’34.57”E, 241m above msl) situated in District Gurdaspur, Punjab (India). The
leaves of Eichhornia crassipes occur in a rosette due to spiral arrangement of petioles.
Each leaf consists of a petiole and a leaf lamina. Petioles are spongy and measure up
to 5 cm in diameter and 30-50 cm in length. They are elongated, swollen in middle and
tapering towards the lamina. The petioles have air filled lacunate tissue, and act as air
bladders providing buoyancy to the plant.
An indigenously designed apparatus was designed to study the sound proofing ability of
Eichhornia crassipes (Fig. 1). The apparatus comprises of a steel cylinder (101). The
3
cylinder has an inverted funnel shaped lid (102). The cylinder (101) has a sound
producing unit (103) whose vibrations have to be analysed. The vibrations and sound
can be measured by sound level meter (104). The apparatus as mentioned above is
used for studying to show that sound proofing capacity of Eichhornia crassipes.
Examples:
A steel cylinder of diameter 26 cm made up of stainless steel was fitted with a speaker
of 50W/16Ω capacity to generate sound inside the cylinder. A funnel shaped lid was
fitted at the mouth of cylinder having an opening of 1 cm diameter.
Compartmentalisation of the cylinder was made with the help of a movable wire mesh
which was placed above the source of sound.
The lower face of sound absorbing material was at a distance of 10 cm from the source
of noise, and the sound level was detected at the distance of 44 cm from the sound
absorber.
The speaker was connected to an amplifier to generate sound of desired loudness from
which the volume was controlled manually. This amplifier was attached to computer,
wherefrom a desired frequency of sound was produced through a software.
The density of the dried petioles of the plant was found to be 0.026 g cm-3 and that of
glasswool was 0.066 g cm-3. Table 1 shows variation in loudness at different
frequencies as a function of the amount of dried petioles of Eichhornia crassipes packed
in cylinder. At a frequency of 1000 Hz, the initial loudness was observed to be 121 dB
which increased to 130 dB and subsequently decreased to 119 dB with increase in the
amount of petioles to 75 to 120 g.
With an increase in the frequency of sound to 2000 Hz, the initial loudness of 128 dB
decreased to 121.7 at 15 g of Eichhornia crassipes packing material, reaching close to
initial value of 127.4 dB at 50 g, after which a continuous decrease occurred till 230 g of
4
petioles loading. A decrease of 10.6 dB was recorded from initial sound level at 2000
Hz.
At frequency of 4000 Hz, initial loudness was observed to be 118 dB which showed a
maximum decrease to 96.6 dB at 230 g Eichhornia crassipes packing material, 21.4 dB
less than initial sound level. Initial loudness of 100 dB was observed at frequency 8000
Hz. 230 g of Eichhornia crassipes packing resulted in a maximum fall in loudness
reaching to 64.1 dB which was 35.9 dB less than initial sound level. However, the
loudness level remained lower than initial value for all weights of Eichhornia crassipes.
Comparison of sound absorption between Eichhornia crassipes and glasswool:
A comparison was made between sound absorption levels by Eichhornia crassipes and
glasswool at different frequencies as shown in Table 2. Three different levels of initial
loudness were set: i) The highest achievable dB at that frequency, ii) the lowest
achievable, and iii) An intermediate level. At 1000 Hz, the initial loudness of 125 dB was
slightly lowered to 123 dB by Eichhornia crassipes petioles packing and 123.6 dB by
glasswool packing. Initial loudness of 111 dB was brought down to 108.3 dB and 110.5
dB with Eichhornia crassipes petioles and glasswool respectively. Similarly, loudness of
90 dB in the empty container was lowered down to 87.4 dB by petioles of Eichhornia
crassipes, and to 89.2 dB by the glasswool. The results show that Eichhornia crassipes
petioles and glasswool are equally effective in attenuating the sound levels.
When 2000 Hz of frequency was applied, there was a slight change in the sound level,
from initial loudness of 125 dB, 116 dB and 90 dB to 125.3 dB, 114.1 dB and 88 dB
respectively with the petioles, while glasswool gave reduction to 125 dB, 113.1 dB and
85 dB respectively. At frequency of 4000 Hz, initial loudness levels were set at 117 dB,
100 dB and 90 dB which were reduced to 108 dB, 83.4 dB and 73.6 dB respectively
with Eichhornia crassipes petioles packing, while glasswool reduced loudness to 110.8
dB, 93.7 dB and 74.8 dB respectively. At frequency of 8000 Hz, initial levels of loudness
were set at 104 dB, 90 dB and 70 dB, which were lowered to 98.3 dB, 80.3 dB and 60.3
5
dB with Eichhornia crassipes petioles packing while glasswool packing lowered the
sound levels to 97 dB, 81.8 dB and 62.7 dB respectively.
Using mass to absorb sound involves a part of the sound energy being used to vibrate
the massive barrier, as observed in the present study. Dampening is the process by
which sonic vibrations are converted into heat. Making a noise transfer through different
layers of material with different densities also helps to dampen noise. Different layers of
Eichhornia crassipes petioles make it suitable for sound proofing.
6
S. No. Sound
frequency
(Hz)
Initial
loudness
without
petioles
(dB)
Loudness (dB, mean ± sd) for different weights of Eichhornia crassipes
10 g 15 g 20 g 25 g 50 g 75 g 100 g 120 g 200 g 230 g
1 1000 121 121.9
± 0.2
122.6
± 0.1
123.7
± 0.3
124.7
± 0.3
126.3
± 0.5
130.0
± 0.2
128.0
± 1.3
119.0
± 0.1
119.1
± 0.1
119.1
± 0.1
2 2000 128 121.9
± 3.5
121.7
± 0.7
123.2
± 0.1
125.5
± 0.1
127.4
± 0.2
126.6
± 0.3
125.4
± 1.0
121.5
± 0.2
121.3
± 0.3
116.6
± 0.1
3 4000 118 108.0
± 2.0
114.0
± 0.1
98.6
± 0.6
106.1
± 0.1
106.1
± 0.1
112.3
± 0.2
105.7
± 0.3
100.5
± 0.5
104.2
± 0.1
96.6
± 0.2
4 8000 100 91.4
± 0.9
95.7
± 1.3
93.2
± 0.2
95.7
± 0.2
93.2
± 0.3
87.0
± 0.1
85.9
± 0.1
81.3
± 0.3
70.5
± 0.1
64.1
± 0.3
Table 1. Change in sound level at different frequencies with increase in weight of Eichhornia crassipes.
7
Significant at *** p ≤ 0.001, ** p ≤ 0.01, * p ≤ 0.05
Table 2. Difference in noise abatement properties of Eichhornia crassipes and glasswool at packing volume of 2000 cm3.
S.No. Frequency
(Hz)
Initial
loudness
(dB)
(mean)
Loudness (dB)
with Eichhornia
crassipes as
noise absorbent
(mean ± sd)
Loudness (dB)
with glasswool
as noise
absorbent
(mean ± sd)
t-value for
difference
between
Eichhornia
crassipes and
glasswool
Sound
attenuation
by
Eichhornia
crassipes
(dB)
Sound
attenuation
by
glasswool
(dB)
1 1000 125
111
90
70
123 ± 0.6
108.3 ± 0.8
87.4 ± 1.2
68.5 ± 0.1
123.6 ± 0.4
110.5 ± 0.3
89.2 ± 0.9
69.5 ± 0.1
1.4
3.5*
2.0
9.3***
2
2.7
2.6
1.5
1.4
0.5
0.8
0.5
2 2000 125
116
90
125.3 ± 0.1
114.1 ± 3.6
88.0 ± 5.2
125 ± 0.0
113.1 ± 5.3
85.0 ± 8.6
11.5***
0.3
0.5
-0.3
1.9
2
0
2.9
5
3 4000 117
100
90
108.0 ± 1.0
83.4 ± 5.7
73.6 ± 6.3
110. 8 ± 0.9
93.7 ± 4.9
74.8 ± 5.7
3.2*
2.4
0.2
9
16.6
16.4
6.2
6.3
15.2
4 8000 104
90
70
98.3 ± 3.7
80.3 ± 3.1
60.3 ± 1.9
97.0 ± 3.9
81.8 ± 6.6
62.7 ± 3.2
0.4
0.4
1.1
5.7
9.7
9.7
7
8.2
7.3
8

CLAIMS:
1. A system comprising Eichhornia crassipes between walls of a container for sound
proofing.
2. The system as claimed in claim 1, wherein whole plant or parts of Eichhornia
crassipes are filled between walls of the container.
3. The system as claimed in claim 2, wherein plant part is petioles of Eichhornia
crassipes.
4. The system as claimed in any of the claim 1, 2 or 3, wherein the density of dry plant
of Eichhornia crassipes is 0.026 g cm-3.
5. A system as claimed in claim 1 wherein the sound frequencies in the range of 1000
hertz to 8000 hertz are attenuated by Eichhornia crassipes.