ASA - ANSI/ASA S3.21
AMERICAN NATIONAL STANDARD Methods for Manual Pure-Tone Threshold Audiometry
|Publication Date:||8 April 2004|
Purpose of standard
Pure-tone threshold audiometry is the procedure used in the assessment of an individual's threshold of hearing for pure tones. Pure-tone threshold audiometry includes manual air-conduction measurements at octave intervals from 250 through 8000 Hz and at intermediate frequencies as needed. When abrupt differences of 20 dB or more occur between adjacent octave frequencies, additional frequencies may be included at the discretion of the tester. Bone-conduction measurements may be carried out if indicated by the test requirements at octave intervals from 250 through 4000 Hz. Also, when required, masking is to be used. The purpose of this standard is to present procedures for conducting manual pure-tone threshold audiometry whose use will minimize intertest differences based on test method.
Limit of standard
This standard is limited to a description of the measurement method of manual pure-tone threshold audiometry. Hearing screening techniques are outside its purview.
Modifications of standard procedures
The procedures described in this standard are usable in a wide variety of circumstances. However, certain individuals, such as young children, developmentally delayed persons, uncooperative persons, or neurologically handicapped persons may require modifications of the procedures. In any instance where response behavior is apt to veer from the usual, the procedure should be modified; however, the modification shall be readily identified and specified by the user, the modifications shall be noted in the reporting of results. Another kind of modification is exemplified as follows: The user of the standard who functions in a work setting which requires monitoring audiometry or diagnostic audiometry will use instrumentation which pertains to that particular setting and the frequencies at which threshold is measured will be dictated by that situation. The choice of frequencies will depend on the purpose for which the procedure is being used.
The procedures detailed in this standard are adapted from those described in the Draft Guidelines for Manual Pure-Tone Audiometry (Wilson et al. 1974) and the Guidelines for a Training Program for Audiometric Technicians (NASNRC, 1973).