How is hearing tested
There are a variety of ways hearing can be tested and one of the most common procedures is with pure tone audiometry. This procedure endeavours to establish the softest sound an individual can hear at a variety of frequencies, or pitches. This is represented in the form of an audiogram, the audiogram plots your hearing levels at various frequencies.
An individuals hearing is measured by placing headphones on the ears or inserts in the ear canal and presented with various tones (frequencies). The sound travels down the ear canal through the middle ear and into the inner ear(cochlea). The person being tested responds by pressing a button signalling to the tester that he or she can hear the tone. This is repeated until the softest audible tone is established for that person which is called their hearing threshold. This is repeated for a series of frequencies ranging from 250 Hertz(Hz) to 8000Hertz(Hz), this measurement is called air conduction testing.
Another measurement is usually undertaken at the same time using a small ossicillating pad or vibrator which is placed on the mastoid bone just behind the ear. The same procedure as with air conduction is used to establish the softest sound an individual can hear at various frequencies. The sound or rather vibrations travel through the bones of the skull to the cochlea(inner ear) bypassing the middle ear structure. This is called bone conduction testing.
The resulting audiogram can tell the clinician a lot about your hearing ability and the type of hearing loss you have. The results can indicate if and where the hearing loss exists, in other words is the loss in the outer, middle or inner ear.
If the air conduction thresholds are the same as bone conduction thresholds then we can reasonable assume that loss lies in the inner ear(cochlea), this type of loss is called a sensori-neural loss.
However, if the bone conduction thresholds are normal and the air conduction thresholds are reduced then we can safely deduce that a conductive loss exits. This means that the inner ear(cochlea) is normal and there is some type of blockage in the outer or middle ear.
If the audiogram indicates that the air conduction and bone conduction thresholds are reduced but not the same a mixed loss exits. This indicates a problem both in the inner and either middle or outer ear.
A mixed or conductive loss may benefit from medical intervention, so its important not to ignore any signs of hearing loss. If you suspect a hearing loss Call now for your no obligation hearing evaluation.