To determine the type of hearing loss you have, what might be causing it, and the best way to treat it, your hearing healthcare professional will likely give you a full hearing test and evaluation, including a visual representation of your hearing, called an audiogram. This audiogram demonstrates which sound frequencies you can hear and at what volume.
The audiogram reads in frequency, sometimes called “pitch”, across the horizontal axis, and in decibels, or loudness, down the vertical axis. The frequencies are low on the left side and then gradually climb to higher pitches on the right side. The decibel scale goes from very soft at the top to very loud at the bottom. 0 db does not mean there is no sound, it simply represents the softest sound a person with normal hearing would be able to detect at least 50% of the time.
The softest sounds you hear at each pitch make up your hearing threshold and those thresholds are marked on your audiogram. Typically, the parts of the test given to you through headphones are called "air" thresholds because the sound must travel through the air of the ear canal to be heard. An O is used for the right ear and an X is used for the left ear to represent your air thresholds.
A bone-conduction vibrator is usually used to test for thresholds as well. A < symbol is used for the right ear and a > symbol is used for the left ear. A bone-conduction vibrator is a device that gently rests on the bone behind the ear and is held in place by a small metal band stretching over the top of the head. This device transmits sound vibrations through the bones and tissues and fluids within the skull directly to the cochlea (the hearing organ of the inner ear). This process allows the examiner to bypass your outside and middle ear areas and test the sensitivity of your inner ear directly.
By combining the results of these two tests, your hearing healthcare professional can determine the type of hearing loss, how well you hear low, medium and high pitches, and which part of the ear is causing the loss.