ABSTRACT
The ultimate test for determining hearing disability is the ability to understand speech; however, speech audiometry has certain limitations for practical use, so pure-tone audiometry is used. The most commonly used frequencies for calculating hearing impairment used to be 500, 1000, and 2000 Hz. More recently. 3000 Hz also has been included, in accordance with the recommendations of the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS). A so-called "low fence" has been determined, below which a hearing loss is considered insufficient to warrant compensation. There is a difference of opinion as to precisely where this low fence should be. The Committee on Hearing and Bio-Acoustics (CHABA) had recommended that the low fence be placed at 35 dB. The AAO-HNS recommends that the low fence be maintained at 25 dB. Each state has its own method of paying disability, using its own formula and providing a method for measuring and calculating binaural hearing impairment. The hearing level for each frequency is the number of decibels at which the listener's threshold of hearing lies above the standard audiometric 0 for that frequency. The hearing level for speech is a simple average of the hearing levels at the frequencies 500, 1000, 2000 and 3000Hz. The following is an example of how to calculate hearing impairment for compensation purposes (AAO-HNS Guidelines, 1978):
2. The percent impairment for each ear should be calculated by multiplying by 1.5% the amount by which the above average hearing threshold level exceeds 25 dB (low fence) up to a maximum of 100%, which is reached at 92 dB (high fence).
