Hearing Tests Are Becoming More Necessary Than Ever Before. 2019-06-06
Our ability to hear is something that is easy to overlook while it is at its peak and it is just as easy to allow the steady decline of that ability, so often a side effect of growing older, to go unnoticed. Like any of our five senses, it is subjective, so the perception of sounds and their intensity are prone to natural but relatively minor variations between individuals. Until comparatively recently, while some infants were born deaf, hearing loss was largely the result of illness, accident, or ageing. Today, numerous medications and other ototoxic chemicals are also implicated, but it is those affected by noise-induced hearing loss (NIHL) who now account for most of the hearing tests conducted today.
While NIHL was recognised among the combatants returning from the First World War and correctly attributed to gunfire, doctors had no means with which to accurately assess the degree of their auditory impairment. To make matters worse, the assisted hearing technology of that time was still somewhat limited. It was more than a quarter of a century later, at the end of the second world conflict, that the science we now know as audiology was established, finally providing a totally objective and far more accurate means with which to evaluate auditory efficiency than the whispering technique often employed by GPs in their efforts to provide hearing tests.
The primary tool of the modern audiologist is the audiogram – a graphical representation of just how well a patient is able to perceive sounds at selected frequencies within the accepted range of normal human audibility. Each ear is tested separately and exposed to a tone of gradually increasing intensity, transmitted via an earpiece. Once the subject detects the sound, he or she presses a button, which then produces a corresponding data point on the graph. The process is repeated at different frequencies, and again with the other ear to provide a bilateral auditory profile. Of the various hearing tests used, the audiogram identifies the extent of any impairment at the frequencies tested and can be used later to adjust the performance of a suitable assisted hearing device, so as to best manage the patient’s established difficulties.
There are two main types of hearing loss and a patient may present with either or both of these. Conductive deafness arises as a result of a problem in the outer or middle ear that limits their ability to conduct sound waves, while sensorineural deafness occurs when the action of specialised sensory cells in the cochlea is impaired. To distinguish between these alternatives, the audiologist will need to conduct two additional hearing evaluations known as the Rinne and Weber tests.