U.S. patent application number 11/168730 was filed with the patent office on 2006-02-02 for noise isolation sheet.
This patent application is currently assigned to Nishikawa Rubber Co., Ltd.. Invention is credited to Shinichiro Emori, Yoshihiro Kohara, Yasuyoshi Suzaki.
Application Number | 20060021823 11/168730 |
Document ID | / |
Family ID | 34976684 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060021823 |
Kind Code |
A1 |
Kohara; Yoshihiro ; et
al. |
February 2, 2006 |
Noise isolation sheet
Abstract
There is provided a noise isolation sheet 10 which is comprised
of an optional number of closed-cell foamed layer 11, open-cell
foamed layer 12 and fibered noise absorbing material 13, being
laminated in an optional order, and which insulates the noise near
1000 Hz. Further, there is provided a noise isolation sheet 10
comprised of an optional number of the closed-cell foamed layer 11
and the fibered noise absorbing material 13 being laminated in an
optional order. There is also provided a noise isolation sheet 10
comprised of an optional number of the open-cell foamed layer 12
and the fibered noise absorbing material 13 being laminated in an
optional order. Each noise isolation sheet 10 is used to partially
or fully cover an interior side of a door inner panel of a
vehicle.
Inventors: |
Kohara; Yoshihiro;
(Hiroshima-Shi, JP) ; Suzaki; Yasuyoshi; (Aki-Gun,
JP) ; Emori; Shinichiro; (Hatsukaichi-Shi,
JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 5TH AVE FL 16
NEW YORK
NY
10001-7708
US
|
Assignee: |
Nishikawa Rubber Co., Ltd.
Hiroshima-shi
JP
|
Family ID: |
34976684 |
Appl. No.: |
11/168730 |
Filed: |
June 28, 2005 |
Current U.S.
Class: |
181/290 ;
181/294 |
Current CPC
Class: |
B32B 5/24 20130101; B32B
5/18 20130101; B32B 5/245 20130101; B32B 2266/08 20130101; B32B
5/32 20130101; B32B 2305/022 20130101; G10K 11/168 20130101; B32B
2307/10 20130101; B32B 2307/102 20130101; B32B 2605/08 20130101;
B32B 2266/06 20130101; B32B 2305/20 20130101; B60R 13/0815
20130101 |
Class at
Publication: |
181/290 ;
181/294 |
International
Class: |
E04B 1/82 20060101
E04B001/82; E04B 1/84 20060101 E04B001/84; E04B 2/02 20060101
E04B002/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 29, 2004 |
JP |
JP2004-221756 |
Claims
1. A noise isolation sheet characterized in that it comprises an
optional number of closed-cell foamed layer, open-cell foamed layer
and fibered noise absorbing material, wherein said closed-cell
foamed layer, open-cell foamed layer and fibered noise absorbing
material are laminated in an optional order.
2. A noise isolation sheet characterized in that it comprises an
optional number of closed-cell foamed layer and fibered noise
absorbing material, wherein said closed-cell foamed layer and
fibered noise absorbing material are laminated in an optional
order.
3. A noise isolation sheet characterized in that it comprises an
optional number of open-cell foamed layer and fibered noise
absorbing material, wherein said open-cell foamed layer and fibered
noise absorbing material are laminated in an optional order.
4. A noise isolation sheet characterized in that it is used for
partially or fully covering an interior side of a door inner panel
of a vehicle, comprising an optional number of closed-cell foamed
layer, open-cell foamed layer and fibered noise absorbing material,
wherein said closed-cell foamed layer, open-cell foamed layer and
fibered noise absorbing material are laminated in an optional
order.
5. A noise isolation sheet characterized in that it is used for
partially or fully covering an interior side of a door inner panel
of a vehicle, comprising an optional number of closed-cell foamed
layer and fibered noise absorbing material, wherein said
closed-cell foamed layer and fibered noise absorbing material are
laminated in an optional order.
6. A noise isolation sheet characterized in that it is used for
partially or fully covering an interior side of a door inner panel
of a vehicle, comprising an optional number of open-cell foamed
layer and fibered noise absorbing material, wherein said open-cell
foamed layer and fibered noise absorbing material are laminated in
an optional order.
7. A noise isolation sheet claimed in claim 4 characterized in that
a layer positioned in an outermost exterior side of a vehicle is
the closed-cell foamed layer.
8. A noise isolation sheet claimed in claim 6 characterized in that
a layer positioned in an outermost exterior side of a vehicle is
the open-cell foamed layer.
9. A noise isolation sheet claimed in claim 1 characterized in that
said fibered noise absorbing material is an urethane chip felt or
resin felt.
10. A noise isolation sheet claimed in claim 5 characterized in
that a layer positioned in an outermost exterior side of a vehicle
is the closed-cell foamed layer.
11. A noise isolation sheet claimed in claim 10 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
12. A noise isolation sheet claimed in claim 1 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
13. A noise isolation sheet claimed in claim 2 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
14. A noise isolation sheet claimed in claim 3 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
15. A noise isolation sheet claimed in claim 4 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
16. A noise isolation sheet claimed in claim 5 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
17. A noise isolation sheet claimed in claim 6 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
18. A noise isolation sheet claimed in claim 7 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
19. A noise isolation sheet claimed in claim 8 characterized in
that said fibered noise absorbing material is an urethane chip felt
or resin felt.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a noise isolation sheet which is
used, for example, as a sheet installed to an interior side of an
automobile door.
[0002] There have conventionally been applied various noise
isolation means to an inner side of an automobile door with an aim
of preventing external noise from invading into an interior of the
automobile as well as preventing internal noise from leaking to an
outside. For example, there have been invented such means that a
felt or urethane is attached to a backside of an interior door trim
which is installed to an interior side of a door inner panel, and
that an urethane made product is attached to a door inner
panel.
[0003] Regarding to the prior art described above, the applicant of
this invention has invented a noise isolation sheet and filed it
(Japanese Patent Publication No. 2004-020415) in order to improve a
noise isolation property of the conventional noise isolation means.
As illustrated in FIG. 15, the noise isolation sheet comprises a
foam body (a closed-cell foamed layer 11) which is provided with an
infinite number of closed cells 11a interspersed therein, and
another foam body (an open-cell foamed layer 12) which is provided
with open cells 12a interspersed therein.
[0004] Further, there has been invented a sound-absorbing material
for absorbing noise generated by the aspiration of the air in a
combustion engine (see, for example Japanese Unexamined Patent
Publication No. 8-146967 and Japanese Patent Publication No.
2503215.)
[0005] However, although the noise isolation sheet filed by the
applicant of this invention is superior in a noise isolation
property compared to the conventional art comprising the felt or
the urethane, and it, as illustrated in FIG. 16, is also superior
in the noise isolation property as well as a noise absorbing
property against the noise having a frequency of around 3000 Hz or
higher, it should further be improved in the noise isolation
property as well as the noise absorbing property against the noise
near 1000 Hz. In FIG. 16, "(1) NI sheet" is the noise isolation
sheet the applicant of this invention has previously filed.
Further, "(2) Thinsulate" is a name of a product manufactured by
SUMITOMO 3M Ltd., "(3) chip felt" is an urethane chip felt, and
"(4) pet felt" is a resin felt, and all of them are fibriform noise
absorbing materials having a gravity of about 0.02. Further, "(5)
flexible urethane" is spongiose, and is a flexible foam body formed
by expanding materials which is mainly comprised of polyol and
polyisocyanate. It has a gravity of about 0.02. It should be noted
that "t" in each corresponding parenthesis indicates a thickness
(mm).
[0006] Further, the noise absorbing material disclosed in the
Unexamined Patent Publication No. 8-146967 is only effective in
absorbing the noise in a range of 100 Hz to 300 Hz, and it is not
satisfying in absorbing the noise near 1000 Hz. The noise absorbing
material disclosed in the Japanese Patent Publication No. 2503215
is not satisfying either in absorbing the noise near 1000 Hz.
[0007] It is therefore an object of this invention to provide a
noise isolation sheet which is also fully effective in isolating
the noise near 1000 Hz.
SUMMARY OF THE INVENTION
[0008] In order to solve the above mentioned problems, a noise
isolation sheet according to a first aspect of the invention is
characterized in that it comprises an optional number of
closed-cell foamed layer (11), open-cell foamed layer (12) and
fibered noise absorbing material (13), wherein the closed-cell
foamed layer (11), open-cell foamed layer (12) and fibered noise
absorbing material (13) are laminated in an optional order.
[0009] The closed-cell foamed layer (11) is a foam body in which an
infinite number of dosed cells (11a) are dispersedly formed therein
(see FIG. 15). The open-cell layer (12) is a foam body in which
open cells (12a) are dispersedly formed therein, wherein each open
cell (12a) is formed such that adjacent dosed cells (11a) come to
communicate with each other (see FIG. 15). The open-cell foamed
layer (12) includes a semi-open-cell foamed layer (not illustrated)
which comprises both the dosed cells (11a) and open cells (12a)
dispersedly formed therein.
[0010] A noise isolation sheet (10) according to a second aspect of
the invention is characterized in that it comprises an optional
number of closed-cell foamed layer (11) and fibered noise absorbing
material (13), wherein the closed-cell foamed layer (11) and
fibered noise absorbing material (13) are laminated in an optional
order.
[0011] A noise isolation sheet (10) according to a third aspect of
the invention is characterized in that it comprises an optional
number of open-cell foamed layer (12) and fibered noise absorbing
material (13), wherein the open-cell foamed layer (12) and fibered
noise absorbing material (13) are laminated in an optional
order.
[0012] A noise isolation sheet (10) according to a fourth aspect of
the invention is characterized in that it is used for partially or
fully covering an interior side of a door inner panel (1) of a
vehicle, comprising an optional number of closed-cell foamed layer
(11), open-cell foamed layer (12) and fibered noise absorbing
material (13), wherein the closed-cell foamed layer (11), open-cell
foamed layer (12) and fibered noise absorbing material (13) are
laminated in an optional order.
[0013] A noise isolation sheet (10) according to a fifth aspect of
the invention is characterized in that it is used for partially or
fully covering an interior side of a door inner panel (1) of a
vehicle, comprising an optional number of closed-cell foamed layer
(11) and fibered noise absorbing material (13), wherein the
closed-cell foamed layer (11) and fibered noise absorbing material
(13) are laminated in an optional order.
[0014] A noise isolation sheet according to a sixth aspect of the
invention is characterized in that it is used for partially or
fully covering an interior side of a door inner panel (1) of a
vehicle, comprising an optional number of open-cell foamed layer
(12) and fibered noise absorbing material (13), wherein the
open-cell foamed layer (12) and fibered noise absorbing material
(13) are laminated in an optional order.
[0015] A noise isolation sheet (10) according to a seventh aspect
of the invention is characterized in that, in the fourth or fifth
aspect of the invention, a layer positioned in an outermost
exterior side of a vehicle is the closed-cell foamed layer
(11).
[0016] A noise isolation sheet (10) according to a eighth aspect of
the invention is characterized in that, in the sixth invention, a
layer positioned in an outermost exterior side of a vehicle is the
open-cell foamed layer (12).
[0017] A noise isolation sheet according to a ninth aspect of the
invention is characterized in that, in any of the preceding claims,
the fibered noise absorbing material (13) is an urethane chip felt
or resin felt.
[0018] The numeral in each parenthesis indicates a corresponding
element or matter disclosed in the drawings and the after-mentioned
preferred embodiment of the invention. The same numerals are
provided to the similar portions disclosed in the prior art.
[0019] According to the noise isolation sheet in the first aspect
of the invention, the fibered noise absorbing material is laminated
in addition to the closed-cell foamed layer and the open-cell
foamed layer, so that as illustrated in FIG. 14, there can also be
obtained a great noise isolation property against the noise near
1000 Hz by a performance of the fibered noise absorbing
material.
[0020] The graph shown in FIG. 14 discloses numerical values of the
sound transmission loss (TL [db]) obtained by an experimental test
completed by using four different types of noise isolation sheets.
According to this test result, it is understood that the noise
isolation sheet according to the invention comprised of the
closed-cell foamed layer, the open-cell foamed layer and the
fibered noise absorbing material (which is indicated in the graph
as "(3) NI sheet+Thinsulate") is most effective in the noise
isolation property against the noise near 1000 Hz.
[0021] In addition, another noise isolation sheet according to the
invention (which is indicated as "(4) NI sheet+Thinsulate+NI
sheet") which is comprised of two pieces of NI sheets and the
fibered noise absorbing material, wherein each NI sheet is composed
of the closed-cell foamed layer and the open-cell foamed layer,
comes next to the above-mentioned sheet. Further, the conventional
sheet comprised of the closed-cell foamed layer and the open-cell
foamed layer ("(1) NI sheet") comes next, followed by the sheet
comprised merely of the fibered noise absorbing material ("(2)
Thinsulate (1 piece)"). It should be noted that the noise isolation
sheet "(4)" according to the invention which is comprised of two NI
sheets and the fibered noise absorbing material is most effective
in the noise isolation property against the noise in a range at
1000 Hz and higher.
[0022] Further, the closed-cell foamed layer is also highly
effective in the waterproof property, while the open-cell foamed
layer is highly effective in the noise isolation property.
[0023] According to the noise isolation sheet in the second aspect
of the invention, it is comprised of the closed-cell foamed layer
and the fibered noise absorbing material which is laminated on the
closed-cell foamed layer, so that it is highly effective in
isolating the noise near 1000 Hz by a performance of the fibered
noise absorbing material. Further, this noise isolation sheet is
also highly effective in the waterproof property by a performance
of the closed-cell foamed layer.
[0024] According to the noise isolation sheet in the third aspect
of the invention, the fibered noise absorbing material is laminated
on the open-cell foamed layer, so that it is also highly effective
in isolating the noise near 1000 Hz. Further, this noise isolation
sheet demonstrates a higher property in isolating the noise by a
performance of the open-cell foamed layer.
[0025] According to the noise isolation sheet in the fourth aspect
of the invention, the fibered noise absorbing material is laminated
in addition to the closed-cell foamed layer and the open-cell
foamed layer, so that it is highly effective in isolating the noise
near 1000 Hz. Therefore, by covering with this noise isolation
sheet an interior side of a door inner panel of a vehicle, an
external noise is effectively prevented from invading into an
interior of the vehicle, while an internal noise is prevented from
leaking to the external of the vehicle.
[0026] According to the noise isolation sheet in the fifth aspect
of the invention, the closed-cell foamed layer and the fibered
noise absorbing material are laminated, so that it is highly
effective in isolating the noise near 1000 Hz, and is improved in
the noise isolating property of an interior of a vehicle. Further,
a door of a vehicle is improved in the waterproof property by a
performance of the closed-cell foamed layer.
[0027] According to the noise isolation sheet in the sixth aspect
of the invention, the open-cell foamed layer and the fibered noise
absorbing material are laminated, so that it is also highly
effective in isolating the noise near 1000 Hz, and it can improve
the noise isolation property of an interior of a vehicle. Further,
it can demonstrate the higher noise isolation property by a great
performance of the open-cell foamed layer in isolating the
noise.
[0028] According to the noise isolation sheet in the seventh aspect
of the invention, the layer positioned in the outermost exterior
side of the vehicle in the fourth or fifth aspect of the invention
is the closed-cell foamed layer, so that the door of the vehicle
can be improved in the waterproof property by a performance of the
closed-cell foamed layer which is highly effective in the
waterproof property.
[0029] According to the noise isolation sheet in the eighth aspect
of the invention, the layer positioned in the outermost external
side of the vehicle in the sixth aspect of the invention is the
open-cell foamed layer, so that the vehicle door is improved in the
noise isolation property by a performance of the open-cell foamed
layer which is greatly effective in isolating the noise.
[0030] According to the noise isolation sheet in the ninth aspect
of the invention, the fibered noise absorbing material in any of
the preceding invention is the urethane chip felt or the resin
felt, so that it can demonstrate a highly effective noise isolation
property, and that it is economical.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is an exploded perspective view showing a noise
isolation sheet 10 according to a preferred embodiment of the
invention, which is being installed to an automobile door;
[0032] FIG. 2 is a sectional view along line I-I in FIG. 1 showing
a noise isolation sheet according to a first preferred embodiment
of the invention;
[0033] FIG. 3 is a sectional view along line I-I in FIG. 1 showing
another aspect of a noise isolation sheet according to the first
preferred embodiment of the invention;
[0034] FIG. 4 is a sectional view along line I-I in FIG. 1 showing
further another aspect of a noise isolation sheet according to the
first preferred embodiment of the invention.
[0035] FIG. 5 is a sectional view along line I-I in FIG. 1 showing
still another aspect of a noise isolation sheet according to the
first preferred embodiment of the invention;
[0036] FIG. 6 is a sectional view along line I-I in FIG. 1 showing
still further aspect of a noise isolation sheet according to the
first preferred embodiment of the invention;
[0037] FIG. 7 is a sectional view along line I-I in FIG. 1 showing
a noise isolation sheet according to a second preferred embodiment
of the invention;
[0038] FIG. 8 is a sectional view along line I-I in FIG. 1 showing
another noise isolation sheet according to a second preferred
embodiment of the invention;
[0039] FIG. 9 is a sectional view along line I-I in FIG. 1 showing
a noise isolation sheet according to a third preferred embodiment
of the invention;
[0040] FIG. 10 is a sectional view along line I-I in FIG. 1 showing
another noise isolation sheet according to a third preferred
embodiment of the invention;
[0041] FIG. 11 is a table showing an experimental test result of
the transmitted sound of the noise isolation sheet according to the
preferred embodiment of the invention;
[0042] FIG. 12 is a table showing an experimental test result of
the sound transmission loss of the noise isolation sheet according
to the preferred embodiment of the invention;
[0043] FIG. 13 is a graph showing an experimental test result of
the sound transmission loss of the noise isolation sheet according
to the preferred embodiment of the invention;
[0044] FIG. 14 is another graph showing an experimental test result
of the sound transmission loss of the noise isolation sheet
according to the preferred embodiment of the invention;
[0045] FIG. 15 is a sectional view showing a sheet the applicant of
this invention has previously filed;
[0046] and FIG. 16 is a graph showing the sound absorption
coefficient of the sheet the applicant of this invention has
previously filed as well as the sheets formed by other
materials.
DESCRIPTION OF PREFERRED EMBODIMENT
[0047] A noise isolation sheet 10 according to a first preferred
embodiment of the invention will be described referring to FIGS. 1
to 6. FIG. 1 is an exploded perspective view showing the noise
isolation sheet 10 in an installation posture. Each of FIGS. 2 to 6
is a sectional view along line I-I in FIG. 1 showing the noise
isolation sheet 10.
[0048] Each of those noise isolation sheets 10 is installed between
a door inner panel 1 of an automobile and an interior door trim 2
fully (or partially) covering an interior side of the door inner
panel 1. The noise isolation sheet 10 is comprised of a closed-cell
foamed layer 11, an open-cell foamed layer 12 and a fibered noise
absorbing material 13.
[0049] The closed-cell foamed layer 11 and the open-cell foamed
layer 12 can be made of a synthetic rubber such as EPDM, CR, SBR
and NBR, and in this preferred embodiment, they are made of EPDM
for a reason that it is easily controlled in its gravity. The
fibered noise absorbing material 13 is formed by Thinsulate (a
product name), an urethane chip felt or a resin felt. Those
materials do not make much difference in the noise isolation
property.
[0050] In all of the noise isolation sheets 10, the closed-cell
foamed layer 11 is positioned in an outermost external side of an
automobile door in order to improve the waterproof property of the
door by preventing the rain water and the like from invading into
an interior of the vehicle at an exterior side of the vehicle by a
performance of the closed-cell foamed layer 11 which is highly
effective in the waterproof property. Further, by positioning the
open-cell foamed layer 12 and the fibered noise absorbing material
13 in an internal side of the vehicle, the noise isolation property
of the noise isolation sheet 10 against the noise near 1000 Hz is
improved by a performance of the layer 12 and the material 13, both
of which are highly effective in the noise isolation property.
[0051] As illustrated in FIGS. 2 and 3, the noise isolation sheet
10 according to the preferred embodiment of the invention may be
comprised of a single layer of the closed-cell foamed layer 11, the
open-cell foamed layer 12 and the fibered noise absorbing material
13, or as illustrated in FIGS. 4 to 6, it may be comprised of two
layers (or more than two layers) of the closed-cell foamed layers
11 and the open-cell foamed layers 12 (or the fibered noise
absorbing materials 13). Further, the positioning of the layers 11,
12 and the material 13 can be optionally arranged depending on a
demand.
[0052] Referring to FIGS. 1, 7 and 8, a noise isolation sheet
according to a second preferred embodiment of the invention will be
described. Each of FIGS. 7 and 8 is a sectional view along line I-I
in FIG. 1 showing the noise isolation sheet 10.
[0053] Each of the noise isolation sheets 10 is also installed to
an interior side of a door inner panel 1 of an automobile, and it
is comprised of a closed-cell foamed layer(s) 11 and a fibered
noise absorbing materials 13. The noise isolation sheet 10 shown in
FIG. 7 is comprised of a single layer of the closed-cell foamed
layer 11 and the fibered noise absorbing material 13, whereas the
noise isolation sheet 10 shown in FIG. 8 is comprised of two layers
of the closed-cell foamed layers 11, thereby improving the
waterproof property as well as the noise isolation property. More
than two layers of the fibered noise absorbing materials 13 can be
provided.
[0054] There will be described a noise isolation sheet 10 according
to a third preferred embodiment of the invention referring to FIGS.
1, 9 and 10. Each of FIGS. 9 and 10 is a sectional view along line
I-I in FIG. 1 showing the noise isolation sheet 10.
[0055] This noise isolation 10 is also installed to an interior
side of a door inner panel of an automobile, and is comprised of a
open-cell foamed layer(s) 12 and a fibered noise absorbing
materials 13. Both the open-cell foamed layer 12 and the fibered
noise absorbing material 13 are highly effective in the noise
isolation property, so that this sheet 10 is greatly effective in
isolating the noise of any frequency including the noise near 1000
Hz. A number and a position of the open-cell foamed layer 12 as
well as the fibered noise absorbing material 13 are not
limited.
[0056] The inventor of this invention and his colleagues have
completed an experimental test to seek the noise isolation effect
of the noise isolation sheet 10 according to the preferred
embodiment and compared it with other sheets.
[0057] The table shown in FIG. 11 indicates the transmitted sound
of the noise isolation sheet 10 according to the preferred
embodiment of the invention with the transmitted sound of other
sheets. In this table, "NI sheet" is, as previously indicated, a
sheet in which a dosed-cell foamed layer 11 and an open-cell foamed
layer 12 are laminated. As shown in this table, the numeric values
of the transmitted sound near 1000 Hz is relatively low according
to the noise isolation sheet 10 of the preferred embodiment of the
invention (which are indicated as "NI sheet+Thinsulate", "NI
sheet+felt", "NI sheet+Thinsulate+NI sheet", and "NI sheet+felt+NI
sheet"). It is understood from this result that the noise isolation
sheet 10 according to the preferred embodiment of the invention is
highly effective compared to the conventional sheets.
[0058] The table shown in FIG. 12 indicates the sound transmission
loss of the noise isolation sheet 10 according to the preferred
embodiment of the invention with the sound transmission loss of
other sheets. FIG. 13 is a graph prepared based on the numeric
values shown in FIG. 12. The graph shown in FIG. 14, which is
previously described, is also prepared based on the numeric values
shown in FIG. 12 (it should be noted that the numeric values of "NI
sheet (1 piece)" and "Thinsulate (1 piece)" are excluded from the
table in FIG. 12.)
[0059] It is understood from the table and the graph that the noise
isolation sheet 10 ("(3) NI sheet+Thinsulate") according to the
preferred embodiment of the invention is the highest in the sound
transmission loss in a range of slightly lower than 1000 Hz, and is
highly effective in the noise isolation property compared to the
conventional sheets. It should be noted that the other noise
isolation sheets according to other preferred embodiments of the
invention ("(5) NI sheet+Thinsulate+NI sheet" and "(6) NI
sheet+felt+NI sheet") are also highly effective in the noise
isolation property in a range at 1000 Hz and higher as well as a
range at slightly lower than 1000 Hz.
[0060] Although, in the above-mentioned preferred embodiments, the
noise isolation sheet is described in a case that it is installed
to an automobile door, this invention is not limited to such use,
and it can be applied to other vehicles such as a train and an
airplane as well as a building and the like.
* * * * *