ASTM E492-22

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Designation: E492 − 09 (Reapproved 2016) E492 − 22
Standard Test Method for
Laboratory Measurement of Impact Sound Transmission
Through Floor-Ceiling Assemblies Using the Tapping
Machine
This standard is issued under the fixed designation E492; 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 (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorially corrected 14.1 in April 2016.
INTRODUCTION
This test method is one of several for evaluating the sound insulating properties of building
elements. It is designed to measure the impact sound transmission performance of an isolated
floor-ceiling assembly, in a controlled laboratory environment. Others in the set deal with field
measurement of impact sound transmission through floor-ceiling assemblies (Test Method E1007),
measurement of sound isolation in buildings (Test Method E336), the measurement of sound
transmission through a common plenum between two rooms (Test Method E1414), and the laboratory
measurement of airborne sound transmission loss of building partitions such as walls, floor-ceiling
assemblies, doors, and other space-dividing elements (Test Method E90).
1. Scope
1.1 This test method covers the laboratory measurement of impact sound transmission of floor-ceiling assemblies using a
standardized tapping machine. It is assumed that the test specimen constitutes the primary sound transmission path into a receiving
room located directly below and that a good approximation to a diffuse sound field exists in this room.
1.2 Measurements may be conducted on floor-ceiling assemblies of all kinds, including those with floating-floor or suspended
ceiling elements, or both, and floor-ceiling assemblies surfaced with any type of floor-surfacing or floor-covering materials.
1.3 This test method prescribes a uniform procedure for reporting laboratory test data, that is, the normalized one-third octave band
sound pressure levels transmitted by the floor-ceiling assembly due to the tapping machine.
1.4 Laboratory Accreditation—The requirements for accrediting a laboratory for performing this test method are given in Annex
A2.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
This test method is under the jurisdiction of ASTM Committee E33 on Building and Environmental Acoustics and is the direct responsibility of Subcommittee E33.10
on Structural Acoustics and Vibration.
Current edition approved April 1, 2016Oct. 1, 2022. Published April 2016October 2022. Originally approved in 1973. Last previous edition approved in 20092016 as
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E492 – 09.E492 – 09 (2016) . DOI: 10.1520/E0492-09R16E01.10.1520/E0492-22.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E492 − 22
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C423 Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method
C634 Terminology Relating to Building and Environmental Acoustics
E90 Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements
E336 Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings
E989 Classification for Determination of Single-Number Metrics for Impact Noise
E1007 Test Method for Field Measurement of Tapping Machine Impact Sound Transmission Through Floor-Ceiling Assemblies
and Associated Support Structures
E1414 Test Method for Airborne Sound Attenuation Between Rooms Sharing a Common Ceiling Plenum
E2235 Test Method for Determination of Decay Rates for Use in Sound Insulation Test Methods
2.2 ANSI Standards:
S1.10 Pressure Calibration of Laboratory Standard Pressure Microphones
S1.11 Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters
S1.43 Specification for Integrating-Averaging Sound-Level Meters
S12.51 Acoustics—Determination of Sound Power Levels of Noise Sources Using Sound Pressure—Precision Methods for
Reverberation Rooms
2.3 ISO Standards:
ISO 140/6 Acoustics—Measurement of Sound Insulation in Buildings and of Building Elements Part 6: Laboratory
Measurements of Impact Sound Insulation of Floors
ISO 3741 Determination of Sound Power Levels of Noise Sources Using Sound Pressure—Precision Methods for Reverberation
Rooms
2.4 IEC Standards:
IEC 60942 Electroacoustics—Sound Calibrators
IEC 61672 Electroacoustics—Sound Level Meters—Part 1: Specifications
3. Terminology
3.1 The following terms used in this test method have specific meanings that are defined in Terminology C634:
airborne sound
average sound pressure level
background noise
decay rate
decibel
diffuse sound field
impact insulation class
one-third octave band
receiving room
reverberant sound field
reverberation room
sound absorption
sound pressure level
3.2 Definitions of Terms Specific to This Standard:
3.2.1 receiving room—a reverberation room below the floor specimen under test in which the sound pressure levels due to the
tapping machine are measured.
4. Summary of Test Method
4.1 A standard tapping machine is placed in operation on a floor specimen that is intended to represent a horizontal separation
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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between two rooms, one directly above the other. The average spectrum of the sound pressure levels produced by the tapping
machine is measured in the receiving room below in one-third octave bands.
4.2 Since the spectrum depends on the absorption of the receiving room, the sound pressure levels are normalized to a reference
absorption for purposes of comparing results obtained in different receiving rooms that differ in absorption.
5. Significance and Use
5.1 The spectrum of the noise in the room below the test specimen is determined by the following:
5.1.1 The size and the mechanical properties of the floor-ceiling assembly, such as its construction, surface, mounting or edge
restraints, stiffness, or internal damping,
5.1.2 The acoustical response of the room below,
5.1.3 The placement of the object or device producing the impacts, and
5.1.4 The nature of the actual impact itself.
5.2 This test method is based on the use of a standardized tapping machine of the type specified in 8.1 placed in specific positions
on the floor. This machine produces a continuous series of uniform impacts at a uniform rate on a test floor and generates in the
receiving room broadband sound pressure levels that are sufficiently high to make measurements possible beneath most floor types
even in the presence of background noise. The tapping machine itself, however, is not designed to simulate any one type of impact,
such as produced by male or female footsteps.
5.3 Because of its portable design, the tapping machine does not simulate the weight of a human walker. Therefore, the structural
sounds, i.e., creaks or booms of a floor assembly caused by such footstep excitation is not reflected in the single number impact
rating derived from test results obtained by this test method. The degree of correlation between the results of tapping machine tests
in the laboratory and the subjective acceptance of floors under typical conditions of domestic impact excitation is uncertain. The
correlation will depend on both the type of floor construction and the nature of the impact excitation in the building.
5.4 In laboratories designed to satisfy the requirements of this test method, the intent is that only significant path for sound
transmission between the rooms is through the test specimen. This is not generally the case in buildings where there are often many
other paths for sounds— flanking sound transmission. Consequently sound ratings obtained using this test method do not relate
directly to sound isolation in buildings; they represent an upper limit to what would be measured in a field test.
5.5 This test method is not intended for field tests. Field tests are performed according to Test Method E1007.
6. Test Rooms
6.1 The test facility shall be so constructed and arranged that the test specimen constitutes the only important transmission path
for the tapping machine sound.
NOTE 1—Common methods for ensuring that this requirement is satisfied include mounting the specimen resiliently in the test opening, mounting the
specimen in a resiliently supported test frame, and supporting rooms resiliently. In general, all rigid connections between the specimen and the test rooms
should be avoided.
6.2 The spatial variations of sound pressure level measured in the receiving room shall be such that the precision requirements
in Annex A1 are satisfied at all frequencies.
6.3 Volume of Receiving Room—The recommended minimum volume of the receiving room is 125 m .
NOTE 2—See Test Method E90 for recommendations for new construction.
6.4 Room Absorption—The sound absorption in the receiving room should be low to achieve the best possible simulation of the
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ideal diffuse field condition, and to minimize the region dominated by the direct field of the test specimen. In the frequency range
1/3
that extends from f = 2000/V to 2000 Hz, the absorption in the receiving room (as furnished with diffusers) should be no greater
than:
2/3
A 5 V /3 (1)
where:
V = the room volume, m , and
A = the sound absorption of the room, m .
1/3
6.4.1 For frequencies below f = 2000/V , somewhat higher absorption may be desirable to accommodate requirements of other
test methods (for example, ISO 3741); in any case, the absorption should be no greater than three times the value given by Eq 1.
NOTE 3—For frequencies above 2000 Hz, atmospheric absorption may make it impossible to avoid a slightly higher value than that given in Eq 1.
6.5 During the sound pressure level and sound absorption measurements in the receiving room the average temperature shall be
in the range 22 6 5°C and the average relative humidity shall be at least 30 %.
6.6 During the sound pressure level and the corresponding sound absorption measurements, variations in temperature and
humidity in the receiving room shall not exceed 3°C and 3 % relative humidity respectively. Temperature and humidity shall be
measured and recorded as often as necessary to ensure compliance.
6.6.1 If a relative humidity of at least 30 % can not be maintained in the receiving room, users of the test method shall verify by
calculation that changes in the 10 log A term (see 12.4) due to changes in temperature and humidity do not exceed 0.5 dB.
NOTE 4—Procedures for calculating air absorption are described in Test Method C423.
7. Test Specimens
7.1 The test specimen shall be prepared and described in the test report in accordance with Annex A1 of Test Method E90.
7.2 Size and Mounting—The test specimen shall have a minimum lateral dimension of 2.4 m. An area of at least 10 m is
recommended. The test specimen shall include all of the essential constructional elements and surfacing materials normally found
in an actual installation. Some elements may have to be reduced in size to fit each laboratory’s test opening. The test specimen
shall be sealed to prevent tapping machine operational sounds from entering the room below. The specimen shall be structurally
isolated from the receiving room to avoid significant transmission of vibration from the specimen through the supporting structure
to the room below.
7.3 Floor-surfacing materials, such as vinyl, carpets and pads, especially when installed with adhesive, significantly affect the
response of the test specimen to impacts, both during test and in normal use. Consequently, such materials shall be deemed parts
of the test specimen. The materials and the manner of installing them shall be fully described in the test report. The floor-surfacing
material shall cover the whole test specimen, not merely the portion under the impact machine.
8. Tapping Machine
8.1 This test method is based on the use of a standardized tapping machine that conforms to the following specifications:
8.1.1 The tapping machine shall be motor-driven.
8.1.2 The tapping machine shall have five hammers equally spaced in a line. The distance between centerlines of neighboring
hammers shall be 100 6 3 mm.
8.1.3 Each hammer shall have an effective mass of 500 6 6 g and shall fall freely from a height of 40 6 3 mm.
8.1.4 The falling direction of the hammers shall be perpendicular to the test surface to within 6 0.5°.
8.1.5 The part of the hammer carrying the impact surface shall be cylindrical with a diameter of 30 6 0.2 mm.
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8.1.6 The impact surface shall be of hardened steel and shall be approximately spherical with a curvature radius of 500 6 100
mm.
NOTE 5—The mean curvature radius for each hammer face may be determined using a spherometer or other means.
8.1.7 The time between successive impacts shall be 100 6 20 ms.
8.1.8 Since friction in the hammer guidance system can reduce the velocity of the hammer at impact, the tapping machine shall
be checked for friction between the hammers and the guidance system. Any friction found should be eliminated or reduced as much
as possible.
8.1.9 Following adjustment of the hammer drop in accordance with the specifications, the tapping machine is ready for use on any
floor structure, including those surfaced with soft or resilient materials.
NOTE 6—The above requirements are a subset of the ISO 140/6 requirements.
8.2 Tapping Machine Positions—The tapping machine positions and orientations described in the following must be used. Fig. 1
illustrates one case.
8.2.1 Position 1—The middle hammer of the tapping machine shall be coincident with the midpoint of the floor area, that is, the
point of intersection of floor diagonals. In framed construction, adjust this point to the centerline of the closest structural member
or other support member, and arrange the tapping machine so that all hammers fall on the joist.
8.2.2 Position 2—Same as position 1, except rotate the tapping machine 90° about the axis of the middle hammer.
8.2.3 Position 3—Displace the tapping machine laterally from position 1, such that the long dimension of the machine is centered
midway between and parallel to the central structural member. In the case of homogeneous concrete slab floors or solid deck
construction without joists, the lateral displacement of the tapping machine shall be 0.6 m from that of position 1.
FIG. 1 Tapping Machine Positions on a Floor with Structural Members 610 mm o.c.
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8.2.4 Position 4—Position the tapping machine so that all hammers fall on a 45° radial line extending from the middle hammer
point of position 1. Locate the middle hammer 0.6 m from the midpoint of position 1.
9. Instrumentation Requirements
9.1 The measurement process must account for level fluctuations caused by spatial and temporal variations. Various systems of
data collection and processing are possible, ranging from a single microphone moving continuously, a single microphone placed
in sequence at several measurement positions, to several microphones making simultaneous measurements.
9.2 Microphone Electrical Requirements—Use microphones that are stable and substantially omnidirectional in the frequency
range of measurement, with a known frequency response for a random incidence sound field. (A 13-mm random-incidence
condenser microphone is recommended.) Specifically, microphones, amplifiers and electronic circuitry to process microphone
signals must satisfy the requirements of ANSI S1.43 or IEC 61672 for class 1 sound level meters, except that A, B and C weighting
networks are not required since one-third octave filters are used. Where multiple microphones are used, they shall be of the same
model.
9.3 Calibration—Calibrate each microphone over the whole range of test frequencies as often as necessary to ensure the required
accuracy (see ANSI S1.10). A record shall be kept of the calibration data and the dates of calibration (see A2.4.1).
9.4 The calibration of the entire measurement system shall be checked before each set of measurements using an acoustical
calibrator that generates a known sound pressure level at the microphone diaphragm and at a known frequency. The Class of
Calibrator shall be class 1 or better per ANSI S1.40 and/or IEC 60942. Data resulting from calibration shall be analyzed by the
control chart method described in Part 3 of ASTM STP 15D. The analysis shall be according to the subsection entitled
“Control—No Standard Given”. If changes are made to the microphones or measurement system that result in changes in
calibration values, a new control chart should be started.
9.5 Standard Test Frequencies—Measurements shall be made in all one-third-octave bands with mid-band frequencies specified
in ANSI S1.11 from 100 to 3150 Hz. Additional one-third octave band measurements should be made at 50, 63, and 80 Hz to
accumulate research data.
9.6 Bandwidth—The overall frequency response of the filters used to analyze the microphone signals shall, for each test band,
conform to the specifications in ANSI S1.11 for a one-third octave band filter set, class 1 or better.
10. Measurement of Sound Pressure Levels
10.1 Measurements of the average sound pressure levels shall be made in the receiving room directly below the floor specimen
using a procedure that satisfies the requirements in Annex A1. The measurements shall be in a series of frequency bands specified
in 9.49.5 for each of the tapping machine positions designated in 8.2.
10.2 Background Noise Level—Measurements of the background noise levels shall be made during each test to ensure that
measurements of sound pressure level are not affected by extraneous airborne noise or electrical noise in the receiving system.
These measurements shall be made at the same microphone positions using the same analyzer gain settings used to measure sound
pressure levels generated by the tapping machine.
10.2.1 If the background noise level is more than 10 dB below the combined level of signal plus background, then no correction
is to be made.
10.2.2 If the background noise level is between 10 and 5 dB below the combined level, then adjustments must be made for the
background noise level as follows. If L is the level of the signal and background combined, and L is the level due to background
sb b
noise only, then the adjusted signal level, L , in the absence of background noise is the following:
s
L /10 L /10
sb b
L 5 10log~10 2 10 ! (2)
s
10.2.3 At those frequencies where the background noise level is less than 5 dB below the combined level, subtract 2 dB from the
combined level. In this case, the measurements can be used only to provide an estimate of the upper limit of the impact sound
transmission. Identify such measurements in the test report.
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11. Determination of Receiving Room Sound Absorption
11.1 Measure the mean value of the receiving room absorption at each frequency in accordance with Test Method E2235. The
determination of room absorption shall be made with the receiving room and the specimen in the same condition as for the
measurement of the average sound pressure levels.
12. Calculations
12.1 Averaging Sound Pressure Levels—For each tapping machine position, a set of sound pressure levels corresponding to each
microphone position in the receiving room will be obtained. The space-time average sound pressure level (L¯ ) for one tapping
p
machine position is given by:
n
¯ L /10
i
L 5 10log 10 (3)
S D
p (
n
i51
where:
n = number of microphone positions, and
L = sound pressure level measured at a microphone position for one location of the tapping machine, dB re 20 μPa.
i
12.2 The average one-third octave band sound pressure level (L¯ ) of the four average sound pressure levels measured for each
tapping machine position is given by:
¯
¯
...