The kind of test is determined by the child’s age, development or physiological conditions. Behavioral tests use calibrated speech and pure tones to elicit behavioral responses from a child which are then observed and studied. Pure tones are distinct pitches of sound but sometimes other calibrated signals can be used to get frequency information.
An infant’s eye movements, a head-turn by a toddler, placement of a game piece by a preschooler, or a hand-raise by a grade-schooler can be considered as a behavioral response. Speech responses can be the repetition of words at a soft or comfortable level, or the picture identification of a word.
A physiologic test is used if a behavioral test is not possible because of a child’s young age, developmental delay, or medical condition. Rather than actual hearing tests, physiologic tests are measures that can partially estimate hearing function but can also help find the function of the auditory system that is at fault.
Auditory brainstem response (ABR) test
An infant should be sleeping or sedated for this test. Older and cooperative children are visually occupied in a silent environment. Subjects are made to wear earphones which feed click-type sounds while electrodes measure the hearing nerve’s response to the sounds. The responses are then averaged by a computer and displayed into waveforms which include characteristic waveforms for normal hearing in portions of the speech range. A normal ABR means that a baby is able to hear the specific portion, although this can also be attributed to some medical problems or measurement difficulties. Auditory steady state response (ASSR) test
This is a new test which is still under development. An ASSR has to be done with an ABR so that the child’s hearing can also be assessed. A computer automatically establishes the hearing level after it picks up the brain’s response to the sound that is fed through the subject’s ear canals.
Otoacoustic emissions (OAE) test
Similarly, this is administered to an infant who is sleeping or an older child who is able to stay put. An echo response from the outer hair cells in the inner ear is elicited by introducing various pulse-type sounds from a probe which is placed in the ear canal. The responses are then averaged by a computer. A normal recording shows healthy outer hair cell function, however other parts of the hearing pathway can also cause hearing problems.
A procedure rather than a test, a tympanometry can help identify middle ear problems, like fluid collecting behind the eardrum by showing how the eardrum oscillates when a soft sound and air pressure are introduced in the ear canal.
A tympanogram graphically represents the movement of an eardrum. A "peaked" pattern on a tympanogram can represent the normal movement of the eardrum while a "flat" line will mean that the eardrum is not moving.
Who Performs Hearing Tests?
Specifically, a pediatric audiologist who has experience assisting children with hearing loss. Qualified audiologist also work with physicians, educators, and speech/language pathologists, have specialized training with master’s or doctorate degrees in audiology, have performed internships, and are certified by the American Speech-Language-Hearing Association (CCC-A) or are Fellows of the American Academy of Audiology (F-AAA)