Professional Audiology Testing is Essential to the Management of Hearing Loss
Audiology in its current form is practiced by highly trained and qualified healthcare professionals, but the earliest progress in this field began in the 1920s with the invention of a piece of equipment now known as an audiometer. The device was initially employed more as a research tool rather than for routine diagnostic purposes. In fact, it was not until the mid-1940s, when many of the service men returning home from World War 2 displayed signs of noise-induced hearing loss, that its value as a means of determining the extent of impairment was fully leveraged.
The audiometer soon became a reasonably reliable means to identify those subjects that might benefit from a hearing aid and the science of audiology was born. There have been many significant advances in the allied technology and instrumentation since those early days. Today, new hearing tests based upon several decades of research are available. They employ cutting-edge technological advances to undertake intensive studies of the functioning of the outer and middle ear, as well as the cochlea and the auditory nerve.
The increased knowledge gained from such testing has also led to advances in hearing aid design. Not only have these evolved from rather bulky boxes, connected by cords to an earpiece, to minute devices hidden in the ear canal, but they can also be tuned to amplify the specific frequencies that are most impaired.
A visit to an audiology clinic does not require a letter of referral from a doctor, but an appointment will be necessary. On arrival, the first step will be to conduct a physical examination of the ear, to check for signs of infection of some anatomical abnormality that should, instead, be referred to an ENT specialist. If the preliminary examination shows nothing, then an audiogram will be the next step. This is performed by using the audiometer, which is designed to generate sounds corresponding to frequencies that fall within the range of normal human audibility – between 250 and 8000 Hertz (Hz). Audiology studies on normal subjects confirm that, these sounds should be heard at volumes of 20 decibels (dB) or less.
Where a frequency is not discerned in this range, the volume is increased until it is, and the machine plots the dB value against the frequency, in order to produce a graph known as an audiogram. The test is applied to both sides via the ear canal and also, with a special attachment, via the mastoid bone behind the ear. This helps to distinguish conductive from sensorineural and mixed hearing loss, and will influence its management.
The Ear Institute operates well-equipped, centres throughout South Africa and offers advanced audiology services, hearing aids and cochlear implants.