Page 43 - Fall2021

Adults
Medical
Most of the otologic disease entities known in the twenty- first century had been defined during the nineteenth and early twentieth centuries. Parallel to this increase in knowledge was the advent of successful interven- tions, primarily surgical, for these various conditions. The knowledge of and the effective ways to care for ear diseases required an objective means of diagnosing and evaluating the outcomes of care.
During the nineteenth century, there was the significant development in the science of acoustics, most notably the work by Helmholtz (1863). The otological textbooks of this period emphasized that a requirement for evaluat- ing the patient was to obtain a measure of the patient’s hearing using speech as a qualitative measure. The more quantitative measures were through the use of tuning forks. Several standard utilizations of the tuning fork test were found in the texts then and now.
One such test was known as Weber’s (1834) test. ln this, a 512-Hz tuning fork is placed on the forehead. The patient then reports in which ear the sound is louder. When the patient reports hearing the sound equally in both sides, it is considered normal. When one ear hears the tuning fork louder, this is the defective ear.
Rinne’s (1855) test used a combined testing of air and bone conduction. The normal ear, therefore, hears the tone of the fork longer through the air better than through the cranial bones.
Screening
The first documented screening for hearing in an adult population was carried out by the German military in 1888. Individuals who were being considered for military service were classified so that those with normal hearing were sent to the front and the others served behind the
lines (Dölger, 1927). Then, at the beginning of the twenti- eth century, hearing screening was established for military service in the United Kingdom and the United States.
At the beginning of the twentieth century, deafness of either ear constituted an absolute cause of rejection to serve in the United States Army. The testing criteria were qualitative.
“As the distance at which the natural tone of voice may be heard in a closed room, when both ears are normal,
is about 50 feet, the distance at which the applicant is to stand from the examiner must be as great as the apartments will allow, not to exceed 50 feet. The appli- cant will stand with his back to the examiner, who is to address him in a natural tone of voice. When the distance is less than 40 feet, it should be speci- fied on the examination form, and the tone of voice will be lowered. Failure of the applicant to respond to the address of the examiner will demonstrate a defect” (Politzer, 1902b).
The earliest workplace hearing screening for civilian employees was conducted by railways. These were devel- oped as a result of a series of accidents that appear to have occurred because the engineers, the drivers of the train, had a hearing loss. At the end of the nineteenth century, the European railways had established hearing screening for their employees that held positions in which good hearing was essential for safety. The railroad companies also acknowledged that rail service could cause hearing loss and therefore part of their program was to have peri- odic examinations of the hearing of the critical railroad workers. Politzer stated:
“As many disturbances of hearing develop only during the time of service, such examination would seem of value, in the author’s opinion, only if needed at regular fixed intervals. It may, however, be stated with satisfac- tion that most of the companies have given attention to this proposition” (Politzer, 1901).
Malingering
The increased attention to hearing ability by health workers, industry, and the military resulted in some indi- viduals pretending, malingering, that they had a hearing loss. Some of these were individuals with psychiatric dif- ficulties, others wanting to avoid perilous military service, and others wishing to be employed or remain employed.
As a consequence, a series of tests were developed to detect malingering. One method is the use of the Bárány noise machine. The noise is applied to the purported affected ear, and the patient is then required to read a passage. If the patient raises his/her voice with the noise, then one assumes that the ear being masked is func- tional because the patient can hear the noise. If there is no change in the volume of the reader’s voice, it indicates that the ear subjected to the noise is hearing impaired (McKenzie, 1920).
Fall 2021 • Acoustics Today 43