ASTM C634-13(2021)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C634 − 13 (Reapproved 2021)
Standard Terminology Relating to
Building and Environmental Acoustics
This standard is issued under the fixed designation C634; 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.
INTRODUCTION
In some of the entries, those that are measures of physical quantities, the term is followed by several
items: an abbreviation or a symbol, or both, the dimensions of quantities, the measurement units, and
the part of speech. The abbreviation, where applicable, indicates the term as typically referenced. The
symbol stands for the magnitude of the quantity in mathematical expressions. The dimensions of a
quantity express its measure in terms of three fundamental quantities: M for mass, L for length, and
T for time. Speed, for instance, is the quotient obtained when the distance an object moves is divided
−1
by the time involved. The dimensions are [LT ], the negative exponent indicating division. The
measurement units are consistently in SI, Le Système International d’Unités. Those still using the cgs
(centimetre-gram-second) or the inchpound system of units are referred for most of the conversion
factors to IEEE/ ASTM SI 10. Some conversion factors are listed in Section 5 of this document for
convenient reference.
The dimensions of a quantity are the same regardless of the units in which the quantity is measured.
−1
Speed has the dimensions [LT ] whether it is measured in miles per hour, feet per second, or metres
per second. Quantities with different dimensions are not the same. Flow resistance and specific flow
resistance, for instance, are quantities of different kinds even though the names are similar. On the
other hand, quantities with the same dimensions are not necessarily of the same kind. Sound energy
−1 −2
density, for instance, has the same dimensions as sound pressure, [ML T ], but it is not a kind of
sound pressure. Nor is absorption with the dimensions [L ] a kind of area.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This terminology covers terms and definitions related to
C367 Test Methods for Strength Properties of Prefabricated
environmental acoustics. Only definitions common to two or
Architectural Acoustical Tile or Lay-In Ceiling Panels
more standards under the jurisdiction of Committee E33 are
C384 Test Method for Impedance and Absorption of Acous-
listed here. The purpose of this terminology is to promote
tical Materials by Impedance Tube Method
uniformity of key definitions. Definitions pertinent to only one
C423 Test Method for Sound Absorption and Sound Absorp-
standard and exceptions to the definitions listed below are
tion Coefficients by the Reverberation Room Method
contained in the individual standards and should be used when
C522 Test Method for Airflow Resistance of Acoustical
following those standards.
Materials
1.2 This international standard was developed in accor-
C635 Specification for Manufacture, Performance, and Test-
dance with internationally recognized principles on standard-
ing of Metal Suspension Systems for Acoustical Tile and
ization established in the Decision on Principles for the
Lay-in Panel Ceilings
Development of International Standards, Guides and Recom-
C636 Practice for Installation of Metal Ceiling Suspension
mendations issued by the World Trade Organization Technical
Systems for Acoustical Tile and Lay-In Panels
Barriers to Trade (TBT) Committee.
E90 Test Method for Laboratory Measurement of Airborne
Sound Transmission Loss of Building Partitions and
Elements
This terminology is under the jurisdiction of ASTM Committee E33 on
Building and Environmental Acoustics and is the direct responsibility of Subcom-
mittee E33.07 on Definitions and Editorial. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2021. Published February 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ε1
approved in 1969. Last previous edition approved in 2013 as C634 – 13 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0634-13R21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C634 − 13 (2021)
E336 Test Method for Measurement of Airborne Sound E1503 Test Method for Conducting Outdoor Sound Mea-
surements Using a Digital Statistical Sound Analysis
Attenuation between Rooms in Buildings
System
E413 Classification for Rating Sound Insulation
E1573 Test Method for Measurement and Reporting of
E477 Test Method for Laboratory Measurements of Acous-
Masking Sound Levels Using A-Weighted and One-Third-
tical and Airflow Performance of Duct Liner Materials and
Octave-Band Sound Pressure Levels
Prefabricated Silencers
E1574 Test Method for Measurement of Sound in Residen-
E492 Test Method for Laboratory Measurement of Impact
tial Spaces
Sound Transmission Through Floor-Ceiling Assemblies
E1686 Guide for Applying Environmental Noise Measure-
Using the Tapping Machine
ment Methods and Criteria
E557 Guide for Architectural Design and Installation Prac-
E1704 Guide for Specifying Acoustical Performance of
tices for Sound Isolation between Spaces Separated by
Sound-Isolating Enclosures
Operable Partitions
E1780 Guide for Measuring Outdoor Sound Received from
E596 Test Method for Laboratory Measurement of Noise
a Nearby Fixed Source
Reduction of Sound-Isolating Enclosures
E2179 Test Method for Laboratory Measurement of the
E756 Test Method for Measuring Vibration-Damping Prop-
Effectiveness of Floor Coverings in Reducing Impact
erties of Materials
Sound Transmission Through Concrete Floors
E795 Practices for Mounting Test Specimens During Sound
E2202 Practice for Measurement of Equipment-Generated
Absorption Tests
Continuous Noise for Assessment of Health Hazards
E966 Guide for Field Measurements of Airborne Sound
E2235 Test Method for Determination of Decay Rates for
Attenuation of Building Facades and Facade Elements
Use in Sound Insulation Test Methods
E989 Classification for Determination of Single-Number
E2249 Test Method for Laboratory Measurement of Air-
Metrics for Impact Noise
borne Transmission Loss of Building Partitions and Ele-
E1007 Test Method for Field Measurement of Tapping
ments Using Sound Intensity
Machine Impact Sound Transmission Through Floor-
E2459 Guide for Measurement of In-Duct Sound Pressure
Ceiling Assemblies and Associated Support Structures
Levels from Large Industrial Gas Turbines and Fans
E1014 Guide for Measurement of Outdoor A-Weighted
E2638 Test Method for Objective Measurement of the
Sound Levels
Speech Privacy Provided by a Closed Room
E1042 Classification for Acoustically Absorptive Materials
IEEE/ ASTM SI 10 Standard for Use of the International
Applied by Trowel or Spray
System of Units (SI): The Modern Metric System
E1050 Test Method for Impedance and Absorption of
2.2 ANSI Standard:
Acoustical Materials Using a Tube, Two Microphones and
ANSI S1.4 Specification for Sound Level Meters
a Digital Frequency Analysis System
ANSI S1.6 Preferred Frequencies, Frequency Levels, and
E1110 Classification for Determination of Articulation Class Band Numbers for Acoustical Measurements
E1111 Test Method for Measuring the Interzone Attenuation ANSI S1.11 Octave-Band and Fractional Octave-Band Ana-
of Open Office Components log and Digital Filters, Specifications for
E1123 Practices for Mounting Test Specimens for Sound
3. Terminology
Transmission Loss Testing of Naval and Marine Ship
Bulkhead Treatment Materials
3.1 If the term sought by the user cannot be found in 3.2, it
E1124 Test Method for Field Measurement of Sound Power
may be found in 4.1.
Level by the Two-Surface Method
3.2 Definitions:
E1130 Test Method for Objective Measurement of Speech −4 −1
acoustic impedance, Z[ML T ], (mks acoustic ohm or
Privacy in Open Plan Spaces Using Articulation Index
Pa·s/m ), n—of a surface, for a given frequency, the complex
E1179 Specification for Sound Sources Used for Testing
quotient obtained when the sound pressure averaged over the
Open Office Components and Systems
surface is divided by the volume velocity through the
E1222 Test Method for Laboratory Measurement of the
surface. The real and imaginary components are called,
Insertion Loss of Pipe Lagging Systems
respectively, acoustic resistance and acoustic reactance.
E1264 Classification for Acoustical Ceiling Products
Z[R1jX (1)
E1265 Test Method for Measuring Insertion Loss of Pneu-
where:
matic Exhaust Silencers
E1289 Specification for Reference Specimen for Sound
R = the real component of acoustic impedance, and
Transmission Loss X = the imaginary component of acoustic impedance.
E1332 Classification for Rating Outdoor-Indoor Sound At-
acoustical barrier, n—contiguous objects such as solid walls,
tenuation
buildings, or earthen berms that substantially block the direct
E1374 Guide for Office Acoustics and Applicable ASTM
Standards
E1414 Test Method for Airborne Sound Attenuation Be- 3
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
tween Rooms Sharing a Common Ceiling Plenum 4th Floor, New York, NY 10036, http://www.ansi.org.
C634 − 13 (2021)
path of sound between a source and receiver, and which, if where:
¯
they have an open edge or edges allowing diffraction around
L = average sound pressure level, dB,
p
them, are sufficiently wide and high to cause significant
n = number of individual sound pressure levels,
reduction of the sound traveling from the source to the p = rms pressure at an individual position or time, or both,
i
Pa,
receiver.
p = 20 µPa, reference sound pressure, and
acoustical material, n—any material considered in terms of its
L = an individual sound pressure level, dB.
i
acoustical properties. Commonly and especially, a material
If conditions warrant, an integral expression may be used:
designed to absorb sound.
1 t2
¯ 2 2
L 5 10log p t /p dt (4)
S * ~ ~ ! ! D
p 10 0
t1
T
admittance ratio, yρc[dimensionless], n—the reciprocal of the
impedance ratio. The real and imaginary components are
where:
called, respectively, conductance ratio and susceptance
¯
L = average sound pressure level during a specified time
p
ratio.
interval, dB,
ypc[gpc 2 jbpc (2)
T = t − t = a specified time interval, s, min, h, or day,
2 1
p(t) = instantaneous sound pressure, Pa, and
where:
p = 20 µPa, reference sound pressure.
gρc = the real component of admittance ratio, and
bρc = the imaginary component of admittance ratio.
background noise, n—noise from all sources unrelated to a
particular sound that is the object of interest. Background
airborne sound, n—sound that arrives at the point of interest,
noise may include airborne, structureborne, and instrument
such as one side of a partition, by propagation through air.
noise.
−4 −1
airflow resistance, R[ML T ], (mks acoustic ohm or Pa·s/
cutoff frequency, n—of an anechoic wedge or set of wedges,
m ), n—the quotient of the air pressure difference across a
the lowest frequency above which the normal incidence
specimen divided by the volume velocity of airflow through
sound absorption coefficient is at least 0.990.
the specimen. The pressure difference and the volume
velocity may be either steady or alternating. damp, v—to cause a loss or dissipation of the oscillatory or
vibrational energy of an electrical or mechanical system.
−3 −1 2
airflow resistivity, r [ML T ], (mks rayl/m or Pa·s/m ),
o
−1
decay rate, d[T ], (dB/s), n—for airborne sound, the rate of
n—of a homogeneous material, the quotient of its specific
airflow resistance divided by its thickness. decrease of sound pressure level after the source of sound
has stopped; for vibration, the rate of decrease of vibratory
ambient noise, n—the composite of airborne sound from many
acceleration, velocity, or displacement level after the exci-
sources near and far associated with a given environment.
tation has stopped.
No particular sound is singled out for interest.
decibel, dB[dimensionless], n—the term used to identify ten
arithmetic mean sound pressure level, n—of several related
times the common logarithm of the ratio of two like
sound pressure levels measured at different positions or
quantities proportional to power or energy. (See level, sound
different times, or both, in a specified frequency band, the
transmission loss.) Thus, one decibel corresponds to a
0.1
sum of the sound pressure levels divided by the number of
power ratio of 10 and n decibels corresponds to a power
0.1 n
levels.
ratio of (10 ) .
DISCUSSION—The arithmetic mean sound pressure level is sometimes
DISCUSSION—Since the decibel expresses the ratio of two like
used to approximate the average sound pressure level. The accuracy
quantities, it has no dimensions. It is, however, common practice to
of this approximation depends upon the range of sound pressure levels.
treat “decibel” as a unit as, for example, in the sentence, “The average
sound pressure level in the room is 45 decibels.”
¯
average sound pressure level, L [dimensionless], n—of sev-
p
eral related sound pressure levels measured at different posi-
diffraction, n—a change in the direction of propagation of
tions or different times, or both, in a specified frequency band,
sound energy in the neighborhood of a boundary
ten times the common logarithm of the arithmetic mean of the
discontinuity, such as the edge of a reflective or absorptive
squared pressure ratios from which the individual levels were
surface.
derived.
diffuse sound field, n—the sound in a region where the sound
DISCUSSION—1—An average sound pressure level obtained by aver-
intensity is the same in all directions and at every point.
aging the A-weighted sound level continuously over a specified period
is called the time-average sound level.
direct sound field, n—the sound that arrives directly from a
source without reflection.
DISCUSSION—2—Since, by definition, a squared pressure ratio, p /
i
2 L /10
i
p , is equal to 10 , average sound pressure level is calculated from
dummy microphone, n—a microphone substitute which has
the expression:
electrical characteristics identical to a functional
n
microphone, but which has essentially no sensitivity to
¯ L /10
i
L 5 10log 10 (3)
S D
p 10
(
n
i51 incident sound pressure.
C634 − 13 (2021)
field sound transmission class, FSTC[dimensionless], maximum sound level, L [dimensionless], (dB
...