ASTM E1110-06(2019)

Standard Classification for Determination of Articulation Class

SIGNIFICANCE AND USE
4.1 Each weighting factor given in Table 1 represents the fraction of overall speech intelligence contained within the associated one-third octave frequency band.  
4.2 The weighting factors in Table 1 are obtained by multiplying each individual one-third octave band weighting factor of ANSI S3.5-1969 by 300. Articulation class (AC) values are thus related to but distinctly different from articulation index (AI) values. In particular, the AC considers only the effect of signal attenuation; while the AI considers such additional factors as speech level and spectrum and background sound level and spectrum.
Note 2: The AC is similar to the DAI rating proposed by Warnock6 and has been shown to correlate with AI values derived from ANSI S3.5, except where the AI approaches 1 or 0 (AI values range between 1 and 0 and approach 0 with increasing privacy and nonintelligibility). Articulation class values give the reverse. They usually exceed 100 and increase with increasing privacy and nonintelligibility. Extensive comparison between AC ratings and subjective judgments of open-plan speech privacy has not yet been accomplished.
SCOPE
1.1 This classification provides a single figure rating that can be used for comparing building systems and subsystems for speech privacy purposes. The rating is designed to correlate with transmitted speech intelligence between office spaces.  
1.2 Excluded from the scope of this classification are applications involving female speakers or children,2 languages other than English, and sound spectra other than speech. Thus excluded, for example, would be comparisons of building systems or subsystems for their effectiveness in reducing transmitted noise from machinery, industrial processes, bowling alleys, music rooms, places of entertainment, and the like.  
Note 1: Published work by Pearsons, et al, may eventually permit the restriction on female speakers to be relaxed.3  
1.3 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.

General Information

• Status: Published
• Publication Date: 31-Mar-2019
• ICS: 17.140.01 - Acoustic measurements and noise abatement in general
• Technical Committee: E33 - Building and Environmental Acoustics
• Drafting Committee: E33.02 - Speech Privacy

Relations

• Replaces: ASTM E1110-06(2011) - Standard Classification for Determination of Articulation Class
• Effective Date: 01-Apr-2019
• Refers: ASTM E1111-07 - Standard Test Method for Measuring the Interzone Attenuation of Open Office Components
• Effective Date: 01-Apr-2007
• Refers: ASTM E1111-05 - Standard Test Method for Measuring the Interzone Attenuation of Open Office Components
• Effective Date: 01-Apr-2005
• Refers: ASTM E1111-02 - Standard Test Method for Measuring the Interzone Attenuation of Ceiling Systems
• Effective Date: 10-Apr-2002
• Refers: ASTM E1111-92(1996)e1 - Standard Test Method for Measuring the Interzone Attenuation of Ceiling Systems
• Effective Date: 10-Apr-2002
• Referred By: ASTM E1111/E1111M-14(2022) - Standard Test Method for Measuring the Interzone Attenuation of Open Office Components
• Effective Date: 01-Apr-2019
• Referred By: ASTM E1264-23 - Standard Classification for Acoustical Ceiling Products
• Effective Date: 01-Apr-2019
• Referred By: ASTM C634-22 - Standard Terminology Relating to Building and Environmental Acoustics
• Effective Date: 01-Apr-2019
• Referred By: ASTM E1374-18e1 - Standard Guide for Office Acoustics and Applicable ASTM Standards
• Effective Date: 01-Apr-2019

Overview

ASTM E1110-06(2019): Standard Classification for Determination of Articulation Class provides a method for assessing the speech privacy performance of building systems and subsystems, particularly in open-plan office environments. Developed by ASTM International, this standard focuses on measuring the articulation class (AC), which represents the effectiveness of architectural elements in reducing speech intelligibility between office spaces. The AC metric enables industry professionals to compare different construction solutions for speech privacy using a single-figure rating.

Key Topics

• Articulation Class (AC): The core of this standard, the AC is calculated based on the sum of weighted sound attenuation levels across a series of 15 frequency bands (200-5000 Hz). Each band's contribution is weighted according to its importance in conveying speech information.

• Weighting Factors: The weighting factors used in AC calculations are derived from ANSI S3.5-1969, adjusted by multiplication with a constant to ensure relevance for office privacy scenarios. These factors represent the proportion of speech intelligence in each one-third octave band.

• Difference from Articulation Index (AI): Although AC is related to the articulation index, it differs fundamentally. AC considers only signal attenuation, whereas AI also accounts for speech level, speech spectrum, and the background noise spectrum. Notably, as AI approaches zero (indicating greater privacy), AC values increase, typically exceeding 100.

• Reporting: AC ratings should be reported to the nearest multiple of ten, along with detailed data for unweighted sound attenuation in each test frequency band.

• Scope and Limitations: The standard is primarily designed for comparing speech transmission and privacy between office spaces using English male speech. It is not applicable to other languages, female or child voices, or different sound sources such as machinery or music.

Applications

Practical Applications

• Open-Plan Office Design: Facility planners, architects, and acoustic consultants rely on the AC rating to evaluate and select building components-such as walls, partitions, and ceiling systems-based on their ability to provide desirable speech privacy between work areas.

• System Comparison: AC values offer a standardized approach for comparing the speech privacy effectiveness of various architectural subsystems and layout options, supporting procurement and specification decisions.

• Privacy Enhancement: Organizations use the AC measurement to ensure compliance with workplace privacy standards, fostering environments where confidential conversations remain protected and distractions are minimized.

• Performance Benchmarking: Manufacturers of acoustic products and building components use AC ratings to demonstrate product performance and to market solutions tailored for office privacy.

Limitations

• The standard excludes the assessment of privacy against non-speech noises (e.g., machinery or music).
• Currently limited to male, English-language speech, although future revisions may expand applicability.

Related Standards

• ASTM E1111: Test Method for Measuring the Interzone Attenuation of Open Office Components, cited as the procedure for measuring sound attenuation required for AC determination.
• ANSI S3.5-1969: Methods for the Calculation of the Articulation Index, a key reference for deriving AC weighting factors.
• WTO TBT Principles: The standard is developed in line with international standardization principles outlined by the World Trade Organization Technical Barriers to Trade Committee.

Relevant Keywords: articulation class, ASTM E1110, speech privacy, open office acoustics, sound attenuation, architectural acoustics, office noise control, open-plan speech privacy.

By providing a robust and standardized method to classify and compare the speech privacy performance of building systems, ASTM E1110-06(2019) is an essential resource for professionals concerned with acoustic control in open-plan workspaces.

Standards Content (Sample)

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.
Designation:E1110 −06 (Reapproved 2019)
Standard Classification for
Determination of Articulation Class
This standard is issued under the fixed designation E1110; 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.
1. Scope 3. Summary of Classification
1.1 This classification provides a single figure rating that 3.1 Articulationclass(AC)isthesumoftheweightedsound
can be used for comparing building systems and subsystems attenuations in a series of 15 test bands. It is calculated as
for speech privacy purposes.The rating is designed to correlate follows:
with transmitted speech intelligence between office spaces.
AC 5 A f w f (1)
~ ! ~ !
( i i
f
i
1.2 Excluded from the scope of this classification are
applications involving female speakers or children, languages
where:
other than English, and sound spectra other than speech. Thus
f = the center frequency of the bands from 200 to 5000
i
excluded, for example, would be comparisons of building
Hz,
systems or subsystems for their effectiveness in reducing
A(f) = the measured attenuation in decibels in the one-third
i
transmitted noise from machinery, industrial processes, bowl-
octave band with center frequency f, and
i
ing alleys, music rooms, places of entertainment, and the like.
w(f) = the weighting for that band, from Table 1.
i
NOTE 1—Published work by Pearsons, et al, may eventually permit the 3.2 The sound attenuation for each band is determined in
restriction on female speakers to be relaxed.
accordance with Test Method E1111. In Test Method E1111
1.3 This international standard was developed in accor- interzone attenuation is substituted for sound attenuation.
dance with internationally recognized principles on standard-
4. Significance and Use
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.1 Each weighting factor given in Table 1 represents the
mendations issued by the World Trade Organization Technical
fraction of overall speech intelligence contained within the
Barriers to Trade (TBT) Committee.
associated one-third octave frequency band.
4.2 The weighting factors in Table 1 are obtained by
2. Referenced Documents
multiplying each individual one-third octave band weighting
2.1 ASTM Standards:
factor of ANSI S3.5-1969 by 300. Articulation class (AC)
E1111 Test Method for Measuring the InterzoneAttenuation
values are thus related to but distinctly different from articu-
of Open Office Components
lation index (AI) values. In particular, the AC considers only
2.2 ANSI Standard:
the effect of signal attenuation; while the AI considers such
S3.5 –1969 Methods for the Calculation of the Articulation
additional factors as speech level and spectrum and back-
Index
ground sound level and spectrum.
NOTE 2—The AC is similar to the DAI rating proposed by Warnock
This classification is under the jurisdiction of ASTM Committee E33 on
and has been shown to correlate with AI values derived from ANSI S3.5,
Building and Environmental Acoustics and is the direct responsibility of Subcom-
except where the AI approaches 1 or 0 (AI values range between 1 and 0
mittee
...