Page 45 - January 2009

ANSI STANDARDS: ALIVE AND WELL
IN THE GRADUATE AUDIOLOGY CLASSROOM
Sandra Gordon-Salant
Department of Hearing and Speech Sciences, University of Maryland College Park, Maryland 20742
Audiology graduate curricula are
infused with the basic science
foundations of the profession of
audiology. Virtually all of the work that
audiologists do involves presentation of
acoustic stimuli to clinical patients,
whether during hearing assessment,
hearing aid evaluation and fitting, or
aural rehabilitation. One fundamental
tenet of this work is to ensure that the
signal being delivered through the
instrumentation (including audiome-
ters, aural acoustic immittance units,
and hearing aids) is accurate. A secondary tenet is that the acoustic environment in which tests are conducted, and/or services are delivered to patients (including educational services to students) conforms to minimum requirements for noise and reverberation. Additionally, audiologists may be involved in hearing conservation programs that include noise surveys conducted in the work environment. These surveys must conform to rigorous standards of measure- ment. Fortunately, the American National Standards Institute (ANSI) provides a range of standards for measur- ing sound pressure levels, force levels, and reverberation to verify signal accuracy and environmental sound quality. For the most part, standards that are relevant to the work of audiologists are developed by Accredited Standards Committee S3, Bioacoustics that is sponsored by the Acoustical Society of America (ASA).
There are dozens of ANSI standards that are relevant to the practice of audiology, and they are covered in a variety of courses in the typical audiology curriculum. For example, the standards that describe acoustical measurement of hear- ing aids (e.g., ANSI S3.22-2003: American National Standard Specification of Hearing Aid Characteristics; ANSI S3.46 – 1997, (R 2007): American National Standard Methods of Measurement of Real-Ear Performance Characteristics of Hearing Aids) are usually taught in the sequence of hearing aids courses. The standard on class- room acoustics (ANSI S12.60-2002: American National Standard Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools) is taught in an educational audiology course. Courses on industrial audiol- ogy generally present the standards on measurement of noise in the workplace, as well as the effectiveness of hearing protection. Instrumentation courses and/or courses on hear- ing assessment include material from ANSI S3.6-2004: American National Standard for Audiometers and ANSI S3.39-1987 (R 2007): American National Standard Specifications for Instruments to Measure Acoustic Impedance and Admittance. How is the material taught and
“ANSI standards are alive and well in the audiology curriculum because they teach students to conform to the highest principles of professional practice.”
how do students gain access to the ANSI standards? The balance of this report describes my own experience teaching the American National Standard for Audiometers in the course, Basic Hearing Measurement, that is the gate- way course for the graduate curriculum in audiology at the University of Maryland at College Park.
Course material about the develop- ment of audiometers and physical fea- tures of contemporary audiometers segues into the types of audiometers that
are currently in use, including standard markings denoting these types. Subsequently, the importance of calibrating audiometers on a regular basis is discussed. Students are introduced to the ANSI organization and the role it has played in establishing national standards. Definitions of tech- nical terminology such as Reference Equivalent Threshold Sound Pressure Levels (RETSPLs) are provided, as well as procedures for calibrating the output levels, linearity, and harmonic distortion of audiometers. Students learn about the tolerances associated with each measurement, and how to determine whether or not an audiometer is in calibration. Tables specifying the standard audiometer types, RETSPLs, Reference Equivalent Threshold Force Levels (RETFLs), Equivalent Threshold Sound Pressure Levels (ETSPLs), har- monic distortion levels, and ambient permissible noise levels from the ANSI S3.6, 2004 standard (American National Standard for Audiometers) are discussed in detail. Classroom demonstrations of these measurements with instrumentation needed to perform the calibration are followed by assignment of a calibration lab.
One prevailing issue over the years that I have taught this course has been how to provide the information from the ANSI standard to students while conforming to fair use of this copyrighted material. In previous years, I have relied on secondary sources (e.g., textbooks and journal articles) that reproduced the relevant tables. Unfortunately, the textbooks and articles rapidly became outdated with frequent revisions of this particular standard. An alternative was to distribute selected tables from the standard to provide the essential information required by students to perform the calibration. Both of these methods of delivery were inadequate for con- veying to students the rationale for each of the measurements and the detail of many aspects of the standard. Requiring stu- dents to purchase the entire standard (current cost of $150) was an excessive financial burden for students, who were also required to purchase a textbook for the course.
In November, 2005, the ASA issued a press release (http://www.acosoc.org/standards/Educational%20use%20of
44 Acoustics Today, January 2009