ASTM E795-00

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Designation:E795–00
Standard Practices for
Mounting Test Specimens During Sound Absorption Tests
This standard is issued under the fixed designation E 795; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope the room construction requirements of Test Method C 423.In
most cases, the surface will be the floor of the reverberation
1.1 These practices cover test specimen mountings to be
room.
used during sound absorption tests performed in accordance
with Test Method C 423.
4. Significance and Use
1.2 The values stated in SI units are to be regarded as the
4.1 The sound absorption of a material that covers a flat
standard. The values given in parentheses are for information
surface depends not only on the physical properties of the
only.
material but also on the way in which the material is mounted
2. Referenced Documents over the surface.The mountings specified in these practices are
intended to simulate in the laboratory conditions that exist in
2.1 ASTM Standards:
normal use.
C 423 Test Method for Sound Absorption and Sound Ab-
4.2 Some of the specified mountings require special fixtures
sorption Coefficients by the Reverberation Room Method
or minor deviations from normal practice. These fixtures or
C 634 Terminology Relating to Environmental Acoustics
deviations are to be used only during laboratory tests and
2.2 ISO Standard:
should not be specified for practical installations. They are
ISO 354 Measurement of SoundAbsorption in a Reverbera-
noted in the specifications for the mountings in question by the
tion Room
phrase “for laboratory testing only.”
3. Terminology
4.3 Test reports may refer to these mountings by type
designation instead of providing a detailed description of the
3.1 Definitions of Terms Specific to This Standard:
mounting used.
3.1.1 Except as noted in 4.2, the terms used in these
practices are defined in Terminology C 634.
5. Classification
3.2 The following terms have the meaning noted for these
5.1 The mountings are designated as follows:
practices only:
5.1.1 Type A Mounting—Test specimen laid directly against
3.2.1 sound-absorbing units — consists of test specimens
the test surface (described in detail in Section 6).
that are in direct contact with or suspended from ceilings,
5.1.2 Type B Mounting—Test specimen cemented to gyp-
walls, or other room surfaces. Sound-absorbing units include,
sum board and laid directly against the test surface (described
but are not limited to, baffles, draperies, space absorbers,
in detail in Section 7).
volume absorbers (bass traps), and other three-dimensional
5.1.3 Type C Mounting—Test specimen comprising sound-
objects.
absorptive material behind a perforated, expanded, open facing
3.2.2 test surface—any hard surface over which the test
or other porous material (described in detail in Section 8).
specimen or test specimen mounting is placed for testing in
5.1.4 Type D Mounting—Test specimen mounted on wood
accordance with Test Method C 423. The surface shall satisfy
furring strips (described in detail in Section 9).
5.1.5 Type E Mounting—Test specimen mounted with an air
space behind it (described in detail in Section 10).
These practices are under the jurisdiction of ASTM Committee E-33 on
5.1.6 Type G Mounting—Test specimen is a drapery, win-
Environmental Acoustics and are the direct responsibility of Subcommittee E33.01
dow shade, or blind hung parallel to the test surface (described
on Sound Absorption.
Current edition approved May 10, 2000. Published August 2000. Originally
in detail in Section 11).
published as E 795 – 81. Last previous edition E 795 – 93.
5.1.7 Type H Mounting—Test specimen is a drapery sus-
Annual Book of ASTM Standards, Vol 04.06.
pended away from any vertical surface (described in detail in
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036. Section 12).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E795–00
5.1.8 Type I Mounting—The specimen is a spray- or trowel- between the bottom of the frame and the test surface shall be
applied material on an acoustically hard substrate (described in sealed with duct tape or caulking.
detail in Section 13).
NOTE 1—The Type A mounting is intended to simulate normal use
5.1.9 Type J Mounting—The specimen is a sound-absorbing
where a product, such as carpet, wall panels, or ceiling tile is either laid
unit or set of sound-absorbing units (described in detail in
directly on the floor or attached to a wall or ceiling with adhesive or
Section 14). mechanical fasteners. Panels or tile may be arranged in a pattern that
simulates their actual installation, but the arrangement shall be explicitly
5.1.10 Type K Mounting—Test specimen is an office screen
noted and described in the report.
(described in detail in Section 15).
5.1.11 Type L Mounting—This mounting is for use with
7. Type B Mounting
concrete blocks or block-like specimens that are normally
7.1 Adhere the test specimen to gypsum board laid directly
assembled using mortar (described in detail in Section 16).
against the test surface as shown in Fig. 3. The thickness of the
5.2 Type C, D, E, and G mountings are further designated
gypsum board is not critical.
by a numerical suffix which indicates the distance (in millime-
7.2 Apply the adhesive in accordance with the manufactur-
tres) from the specimen to the test surface rounded to the
er’sinstructions.Iftherearenospecificinstructions,applyfour
nearest integral multiple of 5 mm. For example, a Type E-400
daubs of adhesive to the back of each piece of the test
mounting is a plenum mounting in which the face of the test
specimen.
specimen is 400 mm (15 ⁄4 in.) away from the test surface. The
7.3 For Laboratory Testing Only—Place 3 by 25 by 25-mm
distances specified by the suffixes are as follows:
( ⁄8 by 1 by 1-in.) hardboard shims between the test specimen
5.2.1 For a Type C Mounting—The thickness of the furring
and the gypsum board at the four corners of each piece of test
strips.
specimen.
5.2.2 For a Type D Mounting—The thickness of the furring
7.4 Perimeter Seals, for Laboratory Testing Only—Seal the
strips.
perimeter edges of the test specimen by one of the following
5.2.3 For a Type E Mounting—The distance from the
methods:
exposed face of the test specimen to the test surface.
7.4.1 Cover with tape, caulking compound, or a similar
5.2.4 For a Type G Mounting—The distance from the
product as shown in Fig. 2.
centerline of the hangers to the test surface.
7.4.2 Cover with a wood or metal frame so that the top
surface of the frame is flush with the front face of the test
6. Type A Mounting
specimen as shown in Fig. 2. Minimize air spaces between the
6.1 Lay the test specimen directly against the test surface as
frame and the perimeter edge of the test specimen. Air gaps
shown in Fig. 1.
between the bottom of the frame and the test surface shall be
6.2 Do not use an adhesive that is likely to leave a thin air
sealed with duct tape or caulking.
space behind the test specimen. However, mechanical fasten-
ers, carpet tape, or contact cement may be used to hold the
NOTE 2—The Type B mounting is intended to simulate acoustical
ceiling tiles or other sound-absorptive products adhered to a hard surface
specimen against a vertical or overhead surface or to keep the
with an adhesive. In normal use, this method of application leaves a thin
specimen in contact with the floor.
air space between the product and the surface to which it is adhered. The
6.3 Iftwoormorepiecesofmaterial(orseparatepanels)are
3-mm ( ⁄8-in.) thick hardboard shims are used to control the depth of the
butted together to form the test specimen, it may be advisable
air space during laboratory tests and should not be included in a normal
to cover the joints between adjacent pieces with tape, caulking
installation.
compound, or other material that is not sound absorptive. If the
8. Type C Mounting
joints are sealed in this manner, the test report shall describe
the method of sealing. 8.1 The test specimen shall comprise sound-absorptive ma-
6.4 Perimeter Seals for Laboratory Testing Only—If the terial behind a perforated, expanded, open facing, or other
perimeter edges of the test specimen are not exposed in normal porous material attached to wood furring strips spaced 600 mm
use, seal them by one of the following two methods: (24 in.) on centers and laid directly against the test surface as
6.4.1 Cover with tape, caulking compound, or a similar shown in Fig. 4. The suffix of the mounting designation shall
product as shown in Fig. 2.
be the actual thickness of the furring strips rounded to the
6.4.2 Cover with a wood or metal frame so that the top nearest integral multiple of 5 mm.
surface of the frame is flush with the front face of the test
8.1.1 The length of the furring strips described in 8.1 shall
specimen as shown in Fig. 2. Minimize air spaces between the be shorter than the length of the test specimen by an amount
frame and the perimeter edge of the test specimen. Air gaps
equal to twice the width of the furring strips. This will allow
FIG. 1 Type A Mounting
E795–00
FIG. 2 Typical Edge Seals
FIG. 3 Type B Mounting
1 1 1
1 ⁄2 in.) or 40 by 40 mm (1 ⁄2 by 1 ⁄2 in.), which corresponds to a C-20 or
the placement of a furring strip at each end of the system to act
C-40 mounting.
as an “end cap” and completely enclose the airspace below the
test specimen.
9. Type D Mounting
8.2 Perimeter Seals, for Laboratory Testing Only—The
perimeter furring strips of the test specimen shall be sealed to
9.1 Attachthetestspecimentowoodfurringstripsspacedat
the test surface with tape or caulking compound.
300 mm (12 in.) on centers and laid directly against the test
3 surface as shown in Fig. 5. The suffix of the mounting
NOTE 3—The preferred sizes for furring strips are 20 by 40 mm ( ⁄4 by
E795–00
FIG. 4 Type C Mounting
FIG. 5 Type D Mounting
designation shall be the actual thickness of the furring strips frame and the perimeter edge of the test specimen. Air gaps
rounded to the nearest integral multiple of 5 mm. between the bottom of the frame and the test surface shall be
9.1.1 The length of the furring strips described in 9.1 shall sealed with duct tape or caulking.
be shorter than the length of the test specimen by an amount
3 1
NOTE 4—Thepreferredsizeforfurringstripsis20by40mm( ⁄4by1 ⁄2
equal to twice the width of the furring strips. This will allow
in.). This is a D-20 mounting.
the placement of a furring strip at each end of the system to act
as an “end cap” and completely enclose the airspace below the
10. Type E Mounting
test specimen.
10.1 Mount the test specimen in a fixture that supports the
9.2 Perimeter Seals, for Laboratory Testing Only—Seal the
exposed face of the specimen at a designated distance from the
perimeter edges of the test specimen by one of the following
test surface as shown in Fig. 6. The suffix of the mounting
methods:
designation shall be the distance between the exposed face of
9.2.1 Cover with tape, caulking compound, or a similar
the specimen and the test surface rounded to the nearest
product as shown in Fig. 2.
integral multiple of 5 mm.
9.2.2 Cover with a wood or metal frame so that the top
surface of the frame is flush with the front face of the test 10.2 Mounting Fixture for Laboratory Testing Only—The
specimen as shown in Fig. 2. Minimize air spaces between the mounting fixture shall satisfy the following requirements:
FIG. 6 Type E Mounting
E795–00
10.2.1 The mounting fixture, test specimen, and test surface 11.2 Attach the hangers to a solid beam or plank that is
shall enclose an air space that has no interior partitions. butted against the test surface as shown in Fig. 7. The beam or
10.2.2 The joint between the fixture and the test surface plank should prevent sound waves from passing over the top of
shall be sealed to prevent air leaks between the enclosed space the test specimen, into or out of the space behind it.
and the outside.
NOTE 8—The preferred distance between the centerline of the hangers
10.2.3 The fixture shall include a rigid grid system that
and the test surface is 75 mm (3 in.). If another distance is used, it should
supports the exposed face of the test specimen at the required
be an integral multiple of 25 mm.
distance from the test surface. The distance from the exposed
face of the test specimen (excluding decorative features) to the
12. Type H Mounting
test surface shall not vary by more than 5 mm (0.20 in.), across
12.1 The test specimen shall be a drapery. The distance
the entire face of the specimen.
between the suspended drapery and any vertical surface,
10.2.4 The fixture shall seal the perimeter edges of the test
rotating vane, or diffuser panel shall be consistent with the
specimen, and the top surface of the fixture shall be flush with
requirements of Test Method C 423. The drapery shall not be
the front face of the test specimen as shown in Fig. 6.
parallel to any wall as shown in Fig. 8.
10.2.5 The mounting fixture shall be made of a sturdy
material, such as 20-mm ( ⁄4-in.) thick plywood or 3-mm NOTE 9—Type H mountings are intended to simulate draperies used as
sound-absorbing units.
( ⁄8-in.) thick aluminum.
10.2.6 If a grid system is placed between the panels, on the
13. Type I Mounting
exposed side of the specimen, the grid size and arrangement
shall be noted in the report. 13.1 Spray or trowel the material to be tested on to a
substrate that satisfies the following conditions:
NOTE 5—Type E mountings are intended to simulate a suspended
13.1.1 The substrate shall be no more than 25 mm (1 in.)
ceiling with an open plenum above it.
thick.
NOTE 6—When there is good reason to test on aType E mounting other
than Type E-400, a mounting whose suffix is an integral multiple of 25 is
13.1.2 The sound absorption coefficients of the substrate
preferred (for example, E-375, E-425, and so forth).
shall be less than 0.05 in each frequency band when tested on
NOTE 7—It has been found that if a gasket is used between the test
a Type A mounting in accordance with Test Method C 423.
fixture and the test surface, placing the gasket so that it is flush with the
13.1.3 The substrate shall not cup or wrap after the material
exterior surface of the test fixture will minimized the variability in results.
has been applied.
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