Hearing or audiological evaluations consist of a series of tests used to determine whether a hearing loss exists. If so, these tests also measure the type, degree and configuration of your hearing loss. Hearing can be evaluated several different ways. The battery of tests used is determined individually by your audiologist and is based on several different factors including age and intellectual capabilities.
Adult hearing evaluations may consist of all or some of the following tests:
- Discussion of medical and hearing history
- Physical evaluation of the outer ear
- Tympanometry evaluates the function of the outer and middle ear by measuring the sound energy that flows into and is reflected back from the middle ear. These measurements give us important information about how the eardrum and middle ear are functioning and can help determine if there is excessive fluid present. All these measurements are displayed on a graph called a tympanogram.
- Acoustic reflexes
- Acoustic reflex testing measures the muscle contraction of the stapedius muscle, which contracts in response to loud sound. When combined with other tests, this measurement can help determine where the breakdown occurs (the middle ear, cochlea, auditory nerve etc.) as well as the type of hearing loss.
- Pure tone air conduction
- Pure tone air conduction is designed to determine the softest sounds one can hear at different frequencies via the normal hearing pathway, called air conduction. This is completed by placing earphones or headphone in/on the ears and asking the patient to respond by pressing a button or responding verbally when they hear a tone. The results are charted on an audiogram, which is a graph that shows the type, degree and configurations of hearing loss.
- Pure tone bone conduction
- Pure tone bone conduction is designed to determine the softest sounds one can hear at different frequencies via the bone conduction pathway. Instead of sending the sound through the normal air conduction pathway, bone conduction bypasses the outer and middle ear and sends the tone directly to the inner ear. This is completed by placing a bone oscillator just behind the ear. The oscillator sends out a vibration that passes though the skull to reach the inner ear. The result, when compared to air conduction, can determine where the hearing loss is coming from (outer ear, middle ear, inner ear, or a combination). These results are also plotted on an audiogram.
- Speech testing
- Two types of speech testing are typically completed. The first is called speech reception threshold (SRT), or the softest one can understand a spondaic word (two syllable word with equal stress on both syllables) 50 percent of the time. This level is compare to your pure tone results to confirm the diagnosis. The second is called word recognition (WRS); it is designed to assess how well a person can understand speech. WRS can be completed in quiet or in the presence of background noise and is recorded in percentage form.
Pediatric hearing evaluations can be similar to adult testing or consist with one or more of the following tests:
- Otoacoustic emissions (OAEs)
- OAEs are sounds that originate in the cochlea and travel through the middle ear and into the ear canal. OAE testing is completed by placing a tiny probe fitted with a microphone and speaker that is used to stimulate the cochlea and measure its response. Individuals with normal hearing will produce emissions; when a hearing loss exceeds mild/moderate, no emissions will be produced.
- Visual reinforcement audiometry (VRA)
- Once infants reach 5 or 6 months old, most can be conditioned with positive reinforcement (like a lighted toy or cartoon clip) to turn their head in response to sound. VRA is the most commonly used technique to elicit this head turn. These measures can be reliable and are the first choice for diagnostic testing of auditory function because they provide the most information about the infant’s ability to hear. VRA can be used to test children using insert earphones or headphones; the bone oscillator or hearing aids and can use speech, pure tone or narrowband noise as the stimulus.
- Conditioned play audiometry (CPA)
- Once children reach 30 months they can begin to voluntarily cooperate in hearing testing. CPA uses play to entice a child to cooperate for testing. One technique that is commonly used in CPA is teaching the child to drop a toy in a bucket in response to sound.
- Auditory brainstem response (ABR)
- ABR testing is an objective test that measures the auditory neural activity as it travels through the hearing nerve and through the brainstem. This neural activity is measured by placing electrodes on the head and ears. An ABR can accurately estimate the threshold of hearing at many frequencies. It is commonly used to evaluate a child’s hearing when behavioral testing cannot be completed. ABR is often used on newborns who fail their newborn hearing screening.
A hearing evaluation can benefit individuals of all ages, even those who don’t exhibit signs of hearing loss. Many physicians recommend adding hearing evaluations as a routine part of overall healthcare, much like regular vision exams and dental checkups. Having at least a baseline hearing evaluation can be very helpful if a change in hearing occurs.
Call Watauga Hearing at (423) 928-1901 for more information or to schedule an appointment.