For several years various audiometers intended for general diagnostic purposes have been manufactured and sold to physicians. The early instruments were operated from batteries, but in the last few years operation from the electrical power supply circuit has become general practice. Moreover, in the last few years a number of new manufactures have begun the sale of audiometers. The increase in competitive conditions has resulted in considerable sales pressure on otologists and in extensive advertising of audiometers.
Although the value to the otologist of an accurate and otherwise satisfactory audiometer for diagnostic work is unquestioned, the attempt to form diagnoses on the basis of inaccurate audiograms can only be misleading and wasteful of time to both the physician and the patient. Audiograms taken with various commercial audiometers have not always agreed and, in fact, have been widely divergent in many cases. The question of how the various commercial audiometers compare