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Evaluation From Pure-Tone Audiometry

K. D. KRYTER, PhD

Arch Otolaryngol. 1963;77(6):598-602.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

Introduction

A medical opinion has been given that people with an average pure-tone hearing level of 15 db or less at 500, 1,000, and 2,000 cps will have no impairment in the understanding of everyday speech under everyday listening conditions.¹ The allowed handicap of 15 db* has been called a "fence" and is an important feature of the proposed method of evaluating hearing impairment.¹ Apparently, although no references are cited, the primary data that were used as the basis for making this judgment consisted of so-called threshold of intelligibility scores (the level at which listeners judged they could just begin to understand the speech material) for spondee and phonetically balanced (PB) words obtained under quiet listening conditions.^2,3

The results of a recent experiment⁴ suggest that the recommendations made by the Committee on the Conservation of Hearing of the American Academy of Ophthalmology and Otolaryngology (AAOO) should . . . [Full Text PDF of this Article]

Author Affiliations
CAMBRIDGE, MASS

Footnotes
Submitted for publication Jan 28, 1963.

Bolt Beranek and Newman Inc.

The research results reported herein were, in part, obtained under grant B-1727 of the Institute of Neurological Diseases and Blindness, National Institutes of Health, Public Health Service, United States Department of Health, Education, and Welfare.

It should be noted that this average 15 db hearing level is from present-day audiometric zero. Recent tests have shown that present-day audiometric zero is about 10 db higher than it should be; that is, relative to "true" normal, the prescribed 15 db hearing level is really a 25 db hearing level (ie, 25 db below normal).

For a description of words and sentences used in speech testing see J. P. Egan: Articulation Testing Methods, Laryngoscope 58:955-991, 1948.

In the experiments referred to,⁴ the listeners recorded the words and sentences they heard; their answers were objectively scored in terms of the percentage of key words correct. The results are called intelligibility test scores to distinguish them from the subjectively judged threshold of intelligibility measures used in references 2 and 3. A major argument against threshold of intelligibility tests is that each listener has his own "criterion" of when (at what sound pressure level) he begins to understand speech. Persons with progressively greater degrees of hearing loss may develop progressivelylower standards for judging the threshold of intelligibility and in making their judgments may rely more on the loudness of the speech signal than precise understandability. The loudness of speech, of course, is determined largely by the strong frequency components which lie below about 500-600 cps.

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