In 1967, a screening test for hearing was made available by the installation of four audiometers in a sound-treated room for the Audiology Service. The audiometers were redesigned versions of an earlier model and produced by Tracor, Inc. from Austin, Texas. The installation at Mayo Clinic was unique in the respect that it enabled a single operator to conduct tests simultaneously on four patients.
To a large degree, the test was self-administered. Patients were provided with ear phones (blue for the left ear, red for the right) and a small hand switch. Instructions (repeated in signs on the wall) were, “Press when you hear. Release when you don’t.”
The audiometer produced tones of six frequencies transmitted to the patient through the ear phones. A means to record automatically the patient’s response was built into the audiometer with a stylus that traced a graph on a special form (an audiogram), which could be interpreted to indicate degree of hearing loss.
Mr. Terry Griffing, consultant in Audiology, described the procedure as “a screening test adequate for patients who have normal hearing or limited hearing loss.” A criterion was established for separating those patients in whom further tests should be carried out from those in whom further tests were not considered necessary.
The test took about six minutes, while instructions and calculations required additional time for a total of about fifteen minutes. Four audiometers in simultaneous use allowed testing of about sixteen patients per hour.