ANSI Standards What they are_ ho

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					American National Standards:
 Techniques Used for Infant
   Hearing Screening and
    Threshold Estimation

      Robert Burkard

      NHS, May 2004
Background Information
Functions of ANSI:
-serve as national body for voluntary standards
  activity in US, where standards developing
  groups can cooperate in establishing, approving
  and improving standards based on a consensus
  of all interested parties
-promote voluntary standards system for the good
  of the national economy, to benefit the public
  health, welfare, safety, and to facilitate national
  and international trade/commerce.
The US Voluntary Standardization System: Meeting the global challenge (2/93)
Function of ANSI (continued)
-Establish, distribute, administer procedures and
  criteria for recognition and approval of ANSI
-Encourage existing organizations to develop
  standards and submit them for approval
-Represent the interests of the US voluntary
  standards system in international standards

The US Voluntary Standardization System: Meeting the global challenge (2/93)
1918: ANSI founded- American Engineering
  Standards Committee (AESC) to ‘..ensure that
  US voluntary standards would be produced in a
  manner which eliminated or minimized waste,
  duplication of efforts and conflicting standards’
  (p. 3). Founded by: Am. Soc. Civil. Eng., Am.
  Inst. Mech. Eng., Am. Inst. Elec. Eng (now Inst.
  Electrical and Electronic Eng (IEEE)), Am. Soc.
  Of Testing & Materials, and U.S. Depts. Of War,
  Navy and Commerce.

The US Voluntary Standardization System: Meeting the global challenge (2/93)
•   As of early 1990s:
•   1300 companies members of ANSI
•   250 Organizations
•   30 Government Agencies

• In 1992, there were nearly 11,000 ANSI

The US Voluntary Standardization System: Meeting the global challenge (2/93)
    Standards Development Process
• All Standards approved by ANSI must be submitted
    by an ANSI accredited standards developer.
•   Each method requires:
•   Public Review
•   Voting
•   Consideration and disposition of all views and objections*
•   Appeals procedure

*Consensus means much more than a simple majority, but not
  always unanimity

The US Voluntary Standardization System: Meeting the global challenge (2/93)
Standards Development Process

• There are 3 approved Methods for
  developing a standard:
• Accredited Organization Method
• Accredited Standards Committee Method*
• Accredited Canvass Method
The US Voluntary Standardization System: Meeting the global challenge (2/93)
Accredited Standards Committees

• Accredited Standards Committees involved
  in Acoustics/Vibration Standards:
• S1: Acoustics:
• S2: Mechanical Shock & Vibration
• S3: Bioacoustics
• S12: Noise
Accredited Standards Committees
• All Accredited Standards Committees must have
    an organizational standards Secretariat and
    Standards Manager. The Secretariat for S1, S2,
    S3 and S12 is Acoustical Society of America
    (ASA), and the current Standards Manager is
    Susan Blaeser
•   Organizational members: those companies,
    organizations, government agencies and other
    groups with an interest in the work of that
    committee. Organizational members are elected
    to membership and pay a fee to be an
    organizational member
• Guide to the Participation in the ASA Standards Program (8/03)
Accredited Standards Committees
• Each ASC has individual experts. They
  have no vote in any ASC issues, but they
  can review documents and provide
  comments or recommendations to the
• The Secretariat nominates a Chair and
  Vice Chair to each ASC, and subject to
  ratification by the Committee membership.
  They can serve up to 2, 3-year terms.
• Guide to the Participation in the ASA Standards Program (8/03)
 Working Groups
• Each ASC may establish Working Groups
   (WG) to assist in the development of
   Standards. Each WG has members, and a
   Chair appointed by the ASC chair. WGs, in
   addition to developing standards, may
   assist in providing input or resolving
   comments on balloted standards

• Guide to the Participation in the ASA Standards Program (8/03)
Standards of Interest in Audiology:S1/S12

 • S1: Acoustics: 21 Standards
 • ANSI S1.4-1983 (R 2001) American National
     Standard Specification for Sound Level Meters
 •   S12: Noise: 37 Standards
 •   ANSI S12.60-2002 American National Standard
     Acoustical Performance Criteria, Design
     Requirements and Guidelines for Schools
 (35 dB A, .6 sec reverberation time rooms <10,000 ft3; 35
   dB A, .7 sec RT rooms 10,000-20,000 ft3)
Standards of General Interest to Audiologists

• S3: Bioacoustics: 27 Standards
• ANSI S3.1-1999 American National Standard
    Maximum Permissible Ambient Noise Levels for
    Audiometric Test Rooms
•   ANSI S3.6-2004 American National Standard
    Specification for Audiometers
•   ANSI S3.39-1987 (R 2002) American National
    Standard Specifications for Instruments to
    Measure Aural Acoustic Impedance and
    Admittance (Aural Acoustic Immittance)
Standards of General Interest to Audiologists

• S3.45-1999 American National Standard
  Procedures for Testing Basic Vestibular
• ANSI S3.46-1997 (R 2002) American
  National Standard Methods for the
  Measurement of Real-Ear Performance
  Characteristics of Hearing aids
With the exception of ANSI S12.60 Classroom
acoustics, no ANSI Standards concerning
hearing evaluation have considered the
specific needs of infants/children. It must be
remembered that ANSI Standards do not
typically dictate clinical practice, but rather
deal with issues of instrument capabilities,
calibration to certain values with certain
tolerances, and in some instances refer to
specific normative values, such as RETSPLs
For infant hearing screening/threshold evaluation:

Discuss how we could modify current ANSI Standards to
make them more relevant to hearing testing of

Mention Working Groups currently formed whose standards
would be useful for the hearing testing of children/infants

Suggest standards not currently under development that
are needed for hearing testing of infants and children.

Discuss why harmonization is needed for standards relating
to infant hearing screening and threshold estimation
S3.6 Audiometers: Now includes RETSPLs for insert earphones, which are
commonly used in infant hearing testing. With the small ear canal size in
infants, it seems likely that the real-ear SPL is higher in infants than in
adults with insert earphones calibrated to S3.6. Should infant norms be
developed that account for ear-canal volume differences in infants and

S3.1: The ambient noise standard for Audiometric testing: Many folks are
doing infant hearing testing using OAEs and AEPs.
OAEs are pre-neural, and while the ambient noise level will influence how
much signal averaging is required to pull the OAE from the ambient noise,
the OAE itself is quite immune to noise. It seems likely that there should
be different ambient noise guidelines for hearing testing using OAE than
for perceptual measures. Similarly, for ABRs, which use transient stimuli,
with higher perceptual threshold due to temporal integration, can likely be
performed in higher ambient noise levels than the levels required for
behavioral audiometry
 A list of WGs shows some standards in development that are needed for infant
 hearing testing
                                                   S3/WG76   Computerized Audiometry –
                                                             A.J. Miltich
S3/WG35   Audiometers - R.L. Grason                S3/WG78   Thresholds - W.A. Yost
S3/WG36   Speech Intelligibility - R.S. Schlauch   S3/WG79   Methods for Calculation of the
                                                             Speech Intelligibility Index –
S3/WG37   Coupler Calibration of Earphones - B.
          Kruger                                             C.V. Pavlovic
S3/WG39   Human Exposure to Mechanical             S3/WG81   Hearing Assistance Technologies –
          Vibration and Shock - D.D.                         L. Thibodeau, L. Wilber, Co-Chairs
          Reynolds; H.E. von Gierke, Vice          S3/WG82   Basic Vestibular Function Test
          Chair                                              Battery - C. Wall, III
S3/WG43   Method for Calibration of Bone           S3/WG83   Sound Field Audiometry -
          Conduction Vibrator - J. Durrant                   T.R. Letowski
S3/WG48   Hearing Aids - D.A. Preves
                                                   S3/WG84 Otoacoustic Emissions - G.R.
S3/WG51   Auditory Magnitudes - R. Hellman
S3/WG56   Criteria for Background Noise for
          Audiometric Testing - J. Franks          S3/WG86   Audiometric Data Structures –
S3/WG59   Measurement of Speech Levels                       W.A. Cole, B. Kruger, Co-Chairs
S3/WG60   Measurement of Acoustic Impedance        S3/WG87   Human Response to Repetitive
          and Admittance of the Ear                          Mechanical Shock - N. Alem
S3/WG62   Impulse Noise with Respect to            S3/WG88   Standard Audible Emergency
          Hearing Hazard - J.H. Patterson                    Evacuation and Other Signals –
S3/WG67   Manikins - M.D. Burkhard                           I. Mande
                                                   S3/WG89   Spatial Audiometry in Real and
S3/WG72 Measurement of Auditory                              Virtual Environments - J. Besing
Evoked Potentials - R.F. Burkard                   S3/WG90   Animal Bioacoustics - A.E. Bowles
                                                   S3/WG91   Text-to-Speech Synthesis Systems.-
                                                             A.K. Syrdal, C. Bickley, Co-Chairs
S3/WG72 Measurement of Auditory Evoked
Potentials - R.F. Burkard

Current draft deals with specifications of
acoustic signal generation capabilities of an AEP
instrument. Currently does not deal with the
‘recording’ side of the instrument, nor does it
provide RETSPL values for acoustic transients
S3/WG84    Otoacoustic Emissions - G.R. Long

Working group formed. Bogged down in terms
of definitions, as well as calibration issues. OAE
systems are a bit unique as hearing testing
device, as both signal and response are acoustic,
and thus acoustic calibration becomes doubly
important in this measurement. Some strong
opinions in terms of how to measure system
distortion were forwarded.
New Standards needed for Infant Hearing Testing

We need a standard providing RETSPLs for acoustic transients, as
transients are used in TEOAEs. This must be broad enough to include a
range of earphones used, as well as a reasonable range of transient
envelopes. We must decide the rate at which we determine our
perceptual thresholds, as at high rates we perceptually improve our
threshold due to temporal integration, while such threshold improvement
does not occur for TEOAEs or ABRs at higher rates.

                      For TBs, energy
                      Integrated over
                      1-2 cycles)

                                           Stapells, Picton & Smith (1982):

                                           Click threshold improved with
                                           increasing click rate and click
                                           train duration (ABR does not)

(Suzuki & Horiuchi, 1981)
                                               pSPL is (e.g.) 100 dB
New Standards needed for Infant
                                               p peSPL: 97 dB (3 dB crest factor)
Hearing Testing
                                               p-p peSPL: 91-97 dB
A Standard should be developed that
provides guidance as to how to measure
the level of transients. If using true peak
SPL, we should determine a maximum
integration time for the peak hold
capability of SLMs. We should limit the
use of peSPL to the baseline-to-peak
measure, and encourage folks to report
the peSPL measure in terms of true peak
(add 3 dB, which is the crest factor of a
sine wave). We must all be talking about
the same RETSPL value when reporting
our dB nHL screening levels and the
resulting sensitivity and specificity of our
hearing screening programs.

                                                              (Burkard, 1984)
Harmonization is a goal of the standards community.
Harmonization between ANSI and International
standards wants the homologous standards to be
technically identical. In recent years, it has become
possible for ANSI to Nationally adopt an international
standard (NAIS), and in fact, S3 has done this. The
problem comes with cost recovery. If S3 develops a
standard, then the revenue comes back to the S3
Secretariat (ASA). Revenue from Standards sales serves
to defray the cost of the standards process for ASA. For
an NAIS, most of this revenue goes to ANSI. This is an
untenable situation for ASA. Thus, we are in some cases
now working towards developing ANSI Standards that
are technically identical to ISO or IEC standards, but are
not internationally adopted standards. This will fulfill the
goal of harmonization, but without the financial penalty
of international standards adoption.
Harmonization and Infant Hearing Testing

For US and International Standards:

-Must have equivalent transducer/SLM standards (microphones,
earphone, peak hold)
-Couplers must be acoustically equivalent (new couplers?)
-Recommended stimulus envelopes must be similar. This includes
for aSSR stimuli, as most evidence suggests that aSSR is
superimposing of onset responses, and increases in amplitude for
transient versus SAM/two-tone stimuli, likely due to briefer
risetimes and longer offtimes with transient stimuli
-Accepted acoustic calibration methods (peSPL, pSPL) must
-Once acoustic stimuli and calibration are standardized, groups
such as NHS need to determine optimal stimuli and levels used
for infant hearing screening and threshold estimation, so that
results from different labs/clinics from different countries can be
  The End!


Thanks to Susan
Blaeser and Craig
Champlin for reviewing
an earlier draft of this