The passing of the tuning fork as an instrument of precision in measurements of auditory acuity has been brought about by the recent advances in electrical equipment, particularly in the development of the telephone receiver. With an oscillating electric current and a reliable control of this current in the telephone receiver, accuracy and flexibility not to be secured with the tuning forks have been made possible.
Methods for testing the acuity of hearing for diagnostic purposes have developed along two rather widely diverging paths. From one group of examiners we hear the statement that hearing values for a few tones only are necessary. Opposed to these is another group, who insist that values for the tones of the entire audible range are essential for differential diagnosis. The factors determining the method in each individual case are the training and experience of the examiner, the ease of application of the