Abstracts of Bell System Technical Papers Not Appearing in this Journal (01 January 1926)

1. Industrial or those made for determining the fitness of a candidate for employment. In certain types of work it is particularly important that a prospective employee meet a definite requirement for acuity of hearing. Tests made in the army and navy for various branches of service are conspicuous examples of this kind of test. 

2. Educational or those made for determining the degree of hearing of school children both in the public schools and in the schools for the deaf for the special purpose of determining the proper methods to be used in their education. 

3. Clinical or those made for assisting the physician to make a proper diagnosis of the cause of deafness. 

4. Research or those made to determine new facts about both normal and abnormal hearing. It is highly desirable that a single scale be used for representing the degree of hearing which is independent of the method used and which has a general application to the four purposes enumerated. Such a scale is proposed and it is shown how the commonly made voice test, watch tick, acoumcter, coin click and tuning fork tests can be expressed in terms of hearing loss units on this scale. The paper is concluded by summarizing the different methods for testing the acuity of hearing which are as follows: (1) voice tests, (2) phonograph audiometer, (3) hearing loss for speech calculated from audiogram, which audiogram may be obtained in three ways, (a) tuning forks (constant initial amplitude), (b) tuning forks (comparison with hearing of tester), (c) pitch range audiometer.