Most states have Early Hearing Detection and Intervention (EHDI) programs to make sure that babies are tested before they leave the hospital and that appropriate follow-up is provided for those babies who do not pass an initial screening. Several types of hearing tests are required before a hearing loss is diagnosed.
Quick, non-invasive probe measure of cochlear (inner ear) function. During this test, a small probe is place in the baby’s ear and clicks or tones are played and sent from the probe speaker to the ear canal, through the middle ear, and into the cochlea. Outer hair cells in the cochlea become excited and react by generating and emitting an acoustic response. This emitted response then travels in a reverse direction from the cochlea back to the ear canal, where it is detected by the probe microphone. This is not really a test of what the baby hears, it simply tells the doctors whether the hair cells in the ear are functioning within normal limits.
These are tests which determine the functioning of the middle ear. It only takes from 3 to 30 seconds per ear. It may also be referred to as Immittance Testing, which includes tests called (a) Tympanometry, and (b) Acoustic Reflexes. In this type of evaluation, eardrum mobility is measured under different pressure conditions to determine if any problems exist in the middle ear.
During this test, three small electrodes are placed on the baby’s head, and then clicks or tones are played into little headphones placed over the baby’s ears. The equipment measures the brain’s response to these sounds. This test does not measure what the baby can hear, rather it determines the sounds to which the brain actively responds. This test takes only a few minutes and can be done while the baby is sleeping.
Audiometry involves the use of a sound-treated room in which a child is presented with a variety of sounds from high to low pitches, and from soft to loud intensity. An audiologist will have the child respond to the different sound and document it. A young child can be taught to turn to a sound (behavioral testing), or to place a toy on a box or a ring on a post (play audiolmetry).