Before Modern BTE Hearing Aids
The modern audiology industry dates the end of the World War II, when battle-related hearing loss was widespread. Direct physical injury due to shrapnel, and acoustic trauma from high-intensity artillery and firearm noise were common causes of hearing loss.
In the years after World War II, aural rehabilitation centers opened across the country, with the mission of conserving hearing, diagnosing and rehabilitating hearing loss, and providing educational and professional placement services for the hearing impaired. The banner service provided by these clinics was an audiogram produced by a device known as an audiometer, which remains the in use to this day.
History of the Audiogram and Audiometer
It’s not well known that Alexander Graham Bell is generally credited with the invention of the audiometer (a prolific inventor, his work also included the first metal detector and a device to locate icebergs). Even less well known is the man who developed the first “modern” version of the audiometer in 1899 – Carl E. Seashore. Seashore intended the device to measure “keenness of hearing,” and his version formed the basis for devices commercialized by a company called Western Electric.
By the 1920’s, technological advances had led to more modern systems capable of producing “pure tones” via air circulation. Audiograms – diagrams illustrating hearing thresholds at given sound frequencies – began appearing in medical journals in this time period, and were gradually standardized. By the post-World War II era, automatic audiometers were printing out standardized diagrams without the need for manual transcription by the administrator.
Above: A color-coded blank audiogram, identifying thresholds associated with hearing loss severity (left) and a typical audiogram indicating common high-frequency hearing loss (right)
What Happens in a Hearing Test
An audiometer hearing test is typically given to a person in a soundproof booth wearing headphones connected to the audiometer. The audiometer produces tones at specific frequencies and calibrated volume levels to each ear in sequence. The test administrator notes the loudness, in decibels, on an audiogram.
People having their hearing tested convey that they have heard the tone either raising a hand or pressing a button. The goal is to identify the hearing threshold – or softest tone a person can hear – at each sound frequency. The test administrator notes the results on an audiogram template – frequency is on the x-axis and the loudness on the y-axis. Finally, the points are joined by a line to convey which frequencies are not being heard normally and what degree of hearing loss may be present.
Above: An Audiometer
Where Can I get a Hearing Test?
Hearing tests are available today at many locations across the country. Audiologist clinics, hearing aid dispensing stores, branded stores (eg. Miracle Ear), and Hearing Health clinics in many Costco and Sam’s Club locations, all offer the service. While some audiologists will charge for hearing tests, it typically doesn’t take more than a few local phone calls to locate a cost-free option.
Why is it free? Providing a hearing test on site also creates an excellent opportunity to draw in potential customers and cross-sell hearing aids – the main source of profits for these businesses.
Sources: Vogel, Donald; McCarthy, Patricia; Bratt, Gene; Brewer, Carmen. "The Clinical Audiogram: Its History and Current Use." Communicative Disorders Review. Volume 1, Number 2, pp. 81-94. 2007.