Type of audiometer for determination of acuity for air and bone transmitted sound.

Abstract

A phonograph telephone transmitter is led to the primary of a laboratory induction coil. The secondary of the coil is attached to a loud speaker. A group of individuals may be tested by employing a spoken record, preferably in verse, and gradually shifting the secondary toward the primary until the language is understood. This makes possible a rough separation of the members of the group into those of relatively good and relatively poor acuity. Those with relatively poor acuity may then be re-tested individually by using head-phones instead of the loud speaker; placing the secondary at a remote position and then rotating it across the field of the primary. Or with the secondary in extreme position, a variable resistance may be shunted across the secondary terminals. When the resistance reads zero, nothing passes through the head phones and as the resistance is gradually increased, the threshold may be readily attained and read off in terms of ohms. If the secondary is directly connected to a bone activating telephone receiver such as previously described, 1 the intensity required for bone activation may similarly be empirically determined. The apparatus is suggested as a solution for rapid quantitative testing of school children.