A pure-tone air conduction hearing test determines the faintest tones a person can hear at selected pitches (frequencies), from low to high. During this test, earphones are worn so that information can be obtained for each ear.
The person taking the test may be asked to respond to the sounds in a variety of ways, such as :
The audiologist will conduct tests of listening and speech. These results are also recorded on the audiogram. One test that the audiologist conducts during a hearing test is the speech reception threshold (SRT). This is used with older children and adults, and helps to confirm the pure-tone test results. The SRT records the faintest speech that can be heard half the time. Then the audiologist will record word recognition or the ability to correctly repeat back words at a comfortable loudness level.
Speech testing may be done in a quiet or noisy environment. Difficulty understanding speech in background noise is a common complaint of people with hearing loss, and this information is helpful.
The audiologist may also take measurements that will provide information about how the middle ear is functioning. These measurements include tympanometry, acoustic reflex measures, and static acoustic measures.
Tympanometry assists in the detection of fluid in the middle ear, perforation of the eardrum, or wax blocking the ear canal. Tympanometry pushes air pressure into the ear canal, making the eardrum move back and forth. The test measures the mobility of the eardrum. Graphs are created, called tympanograms. These can reveal a stiff eardrum, a hole in the eardrum, or an eardrum that moves too much.
Acoustic reflex measures add information about the possible location of the hearing problem. Everyone has an acoustic reflex to sounds. A tiny muscle in the middle ear contracts when a loud sound occurs. The loudness level at which the acoustic reflex occurs—or the absence of the acoustic reflex—gives information to the audiologist about the type of hearing loss.
After the test battery is completed, the audiologist will review with you each component of the audiologic evaluation to obtain a profile of hearing abilities and needs. Additional specialized testing may be indicated and recommended based on these initial test results.
The hearing evaluation may result in recommendations related to:
Otoacoustic emissions (OAEs) are sounds given off by the inner ear when the cochlea is stimulated by a sound. When sound stimulates the cochlea, the outer hair cells vibrate. The vibration produces a nearly inaudible sound that echoes back into the middle ear. The sound can be measured with a small probe inserted into the ear canal.
People with normal hearing produce emissions. Those with hearing loss greater than 25–30 decibels (dB) do not produce these very soft sounds. This test can detect blockage in the outer ear canal, as well as the presence of middle ear fluid and damage to the outer hair cells in the cochlea.
An audiological evaluation is much more than “just a hearing test.”