MAICO Model 53C Audiometer (1930)
An audiometer is an apparatus used for precise measurement of a hearer’s sensitivities to different frequencies and volumes. Until the late 1940s when transitions were developed, audiometers used vacuum tubes for amplifying small electrical signals. To test hearing, a patient would wear earphones connected to the audiometer; an audiologist or nurse would then turn the calibrated dials and send a series of tones, asking the patient to raise their hand if a sound was heard. The hearing of speech was also tested by connecting a microphone to the audiometer, upon which an audiologist would utter particular phonetic words and ask the patient to repeat them.
This wood-enclosed model 53C audiometer is one of the earliest manufactured by the Medical Acoustic Instrument Company. Measuring 33 x 22 x 22 cm the device features dials for calibrating results in scales of decibels of hearing loss (dB), ranged between -1dB and +95dB. It could also measure hearing loss on the frequency scale of 1200-6000 Hertz (Hz). The audiometer came enclosed in a walnut veneer case, earphones, and a headband. Dr. L. Cherkas, the Medical Officer of Health at the Peel Regional Public Health Unit (Brampton, Ontario), donated the audiometer to the Museum of Healthcare. While the audiometer was mainly used in hospitals or hearing clinics and employed by otologists or audiologists, during the 1930s and 1940s, hearing tests in Ontario were also overseen by public health nurses who were at the front lines of community health education. Nurses visited schools with portable audiometers to deliver hearing tests for large numbers of schoolchildren and compile statistics for health departments on the range of hearing acuity. The MAICO company even offered inexpensive audiometers to local school systems to aid in diagnosing what they called “neglected handicap,” and advertised their audiometers “school audiometer” to assist in training deaf children in hearing and speech.
The audiometer is central to my historical study of school-based audiometric screenings in Ontario. Until audiometers became portable, the Department of Education would supply schools with their own audiometer, or borrow one, for routine hearing tests. Nurses—and later, audiologists—would conduct these tests, and recommend children tested for poor hearing for further examination by a physician or otologist. The hearing health of Canadian schoolchildren were perceived as fundamental to their overall health and large-scale audiometric screenings were conducted by physiologists. The Department of Physiological Hygiene at the University of Toronto piloted the first survey of the hearing impairment of Canadian schoolchildren in 1933.
What I find interesting about the audiometer is how it played a pivotal role in transforming ideas about audiometry and hearing impairment. As the audiometer became more precise, it became easier to diagnose a hard-of-hearing child in order to prevent permanent deafness. The audiometer was more than a preventive health measure—it was an apparatus that nurses, teachers, and even parents, could use to confirm their “problem child” was only a “hearing problem child” marking childhood disobedience as simply a matter of poor hearing acuity. This could be easily remediable with a hearing aid and regular audiometric screenings.
Historian of Medicine & Technology, Ryerson University.