Hearing aids for infants and young children.
As a result of improved technology, permanent hearing loss can be identified soon after birth, reguardless of age, a child with a sensorineural hearing loss (a hearing problem in the inner ear) should be evaluated by an audiologist to determine which type of hearing aid may be of most benefit.
Why are hearing aids important?
Children who have normal hearing begin using single words at about one year of age.
In reality, a great deal of language is learned before children utter their first word.
Hearing loss can disrupt language development because learning spoken language depends on the
ability to hear speech.
Some studies suggest that the ability to learn language peaks between two to four years of age.
For this reason the earlier that finding and addressing any hearing loss begins, the greater chance of
developing listening abilities and using spoken language.
The use of hearing aids is an integral part of this process.
Audiologists usually recommend hearing aids as soon as possible after a loss is identified. Ideally, an audiology facility
that specializes in serving young children will have a cost-saving loaner hearing aid program
where a loaner hearing aid can be selected immediately after a hearing loss is determined. As more complete information about
a childs hearing loss is obtained, a hearing aid evaluation can be completed to recommend hearing aids
for purchase.
What tests are needed before recommending hearing aids?
Before hearing aids can be purchased for a child, an audiologist must determine the degree of hearing loss. This can be done using special test methods for infants, toddlers and young children.
For very young infants, the auditory brainstem response test (ABR) may be used. Electrodes are placed on the child's scalp using an adhesive, then the child sleeps, sounds are played through earphones. Responses to the sounds are used to determine the degree of hearing loss.
After six months of age, infants, toddlers and older children may be tested with gamelike activities such as visual reinforcement audiometry (VRA) or conditional play audiometry (CPA).
|
In this kind of testing children respond to a number of different high and low pitch (frequency) sounds, as well as to speech. The softest level at which a response is observed indicates how much hearing loss is present. For these, a child's responece to sound are observed by audiologists. an older child may press a button or raise a hand in response to sounds. Although behavioral responses can provide more complete detail about hearing sensitivity across all frequencies, ABR responses may be the only hearing information available from very young children who cannot be tested with behavioral methods. |
|
How are hearing aids selected and evaluated for children?
After determining the drgree of hearing loss and receiving medical clearance to use hearing aids, the audiologists begins the hearing aid evaluation process.
There are several hearing-aid evaluation techniques that are used to select hearing aids for children. Regardless of the technique used the goal of amplification is to enable conversational seech to be heard at a comfortable level. Many audiologists use mathematics to compute values for the hearing aid response based on the amount of hearing loss present so the performance of different hearing aids can be compared to the calculated targets.
Two testing methods are used to determine hearing aid response. The first way of evaluating a hearing aid is called functional response. Functional gain testing is performed in a sound booth using behavorial testing methods similar to those mention above. The softest level at which a child responds to sound while wearing a hearind aid is compared to the softest level at which the child responds to sound without a hearing aid. The difference between aided and unaided responses is called functional gain.
Another method of evaluating hearing aids is probe-microphone testing. In this test, a tiny microphone is placed in the ear canal next to the earmold to measure the performance of hearing aid in the ear, and responsed are analyzed to determine hearing ability.
|
One advantage of this method over functional gain testing is that the maximum level of sound processed by the hearing aid can be measured directly and adjusted on an individual basis to a safe and comfortable level. Another advantage is that probe-microphone measurements also can be completed quickly. A probe-microphone system can also be used to calculate real ear to computer differences (RECD). This is one of the newest methods of estimating hearing aid performance. RECD values are used to estimate the real ear responses of different hearing aids withoug having to perform probe-microphone testing with each individual hearing aid on the child's ear. The RECD procedure can be performed when there are concerns that a child will not be able to sit still long enough to perform traditional probe-microphone testing. |
|
What characteristicts are important when choosing hearing aids for children?
There are several terms you may hear when audiologists discuss the characteristics they consider when selecting hearing aids for children.
Frequency response- is the amount of amplification a hearing aid
provides a cross a frequency range? Amplification is usually provided only in regions where hearing loss
is present.
Gain- is the amount of amplification the hearing aid provides. Gain is expressed in decibles (db).
For example, a powerful hearing aid would have high gain.
Saturation sound pressure level- (SSPL) is the loudest sound the hearing aid an produce, reguardless of the incoming signal or the amount of gain. The SSPL of a hearing aid should be set so that the hearing aid never becomes uncomfortably loud or potentially damaging in the ear.
|
A second consideration is the compatibility of a hearing aid with assistive devices because many children with hearing loss use additional amplification devices, such as FM auditory trainers. A third consideration is the availability of volume-control covers and tamper-resistant battery compartments when selecting hearing aids for infants and toddlers. |
|
Why is a behind-the-ear hearing aid style usually recommended for children?
safety is the overriding concern for the choice of behind-the-ear (BTE) vs.in-the-ear hearing aids for children. BTE hearing aids can be used with earmolds made of soft material as a safety precaution with physically active children.
In general, BTE hearing aids also require fewer repairs then in-the-ear hearing aids, and they are more compatible with assistive devices such as FM auditory trainers. Although assistive devices are not typically used with infants and toddlers, many children with hearing loss use FM auditory trainers and other assistive devices when they begin school.
What happens after the hearing aid evaluation?
The food and drug administration (FDA) recommends a thirty day trail period with each new hearing aid. During this time, the hearing aids should be used as much as possible in everyday situations. The audiologist will monitor hearing aid adjustment and benefit during the trial period to determine if any adjustments or changes are necessary. Children's hearing and hearing aid performance should be reevaluated frequently to monitor hearing sensitivity and hearing aid function. These appointments should be scheduled as recommended by the audiologist.
Identifying a hearing loss and finding appropriate hearing aids for a child is a process that may take weeks or months. Parents play an important part in this process of evaluating and using hearing aid amplification. They provide valuable information about a child's responses and are critical to their child's successful use of hearing aids.
How will having hearing aids benefit my child?
Ideally, hearing aids will enable conversational speech to be heard at a comfortable level. The success of achieving this goal depends on the drgree and configuration of a hearing loss. When sever-to-profound hearing loss is present, hearing aids may not be able to amplify speech to levels where it can be understood clearly; however, hearing aids may still improve sound and speech awareness as well as provide helpful additions to visual and facial cues.
Hearing aids do not restore hearing to normal and may not be effective in all listening situations such as noisy backgrounds or listening to speech at a distance. In more difficult listening situations, an FM auditory trainer or a smaller assistive device may be beneficial.
