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Communication Disorders
Communication Disorders

Assessment Techniques

A common misconception in testing hearing with children is that the child needs to be of a certain age in order to have their hearing tested. This reported age ranges anywhere from three months to five years, and is completely false.

Children of any age can have their hearing tested.

Hearing tests should be administered in a sound-treated booth. Assessment methods vary depending on the child's age or developmental ability, but generally fall into one of two categories: objective or subjective test methods. A description of each of these techniques is found below.

Objective Test Methods

These methods are labeled objective because they do not require active cooperation or any kind of behavioral response by the child. In terms of early identification of hearing loss, the following two test methods are critical.

1. Otoacoustic Emissions

This test is a screening test of cochlear function. It is based upon the discovery that there are low level signals (emissions) that are generated by the organ of hearing (cochlea) in response to sound stimulation, which are able to be measured in the ear canal. These emissions are measured by placing a small probe into the ear canal which is capable of presenting sounds as well as measuring for these very soft sounds. In order to do this, the child needs to be still and quiet, or can be asleep. Information is obtained about each ear separately and, depending upon the stimulus used, the test can detect a cochlear hearing loss that is mild to profound in degree. If the child is relatively quiet, the entire test can be completed in less than one minute. 

An obvious limitation of this test method is that no threshold information is obtained. That is, results are the same for a mild cochlear hearing loss as they are for a profound cochlear hearing loss. In order to obtain actual thresholds so that further recommendations can be made, auditory brainstem testing or a subjective test method must be utilized.  Also, results can be affected by middle ear status, for example, recurrent bouts of otitis media, or persistent congestion and/or insertion of ventilation tubes.

2. Auditory Brainstem Response (ABR)

In order to do this test, recording electrodes are attached to the child. Changes in brainstem activity occurring with the presentation of sound to the child through earphones are measured. An adult or older child would be asked to lay quietly and relax with their eyes closed. Because this is difficult to control in young children, they are most often tested in natural sleep, given an oral sedative to induce sleep, or are given a general anesthetic. Information about the hearing status in each ear can be obtained at or very near to threshold levels.

Subjective Test Methods

1. Behaviour Observation Audiometry (BOA)

This method would be appropriate for children with a developmental age of approximately 0-6 months. The test signal is most often presented through loudspeakers, however headphones could also be used. Following presentation of the test signal, changes in the child's behaviour are noted by the Audiologist. Examples of responses could be a startle, an eye shift or widening of the eyes, a head turn or similar movement, as well as changes in limb movement, breathing, or sucking activities.

Limitations of this method include habituation to sound in the very young child. In addition, most often only suprathreshold information is obtained; thus, only more significant hearing losses can be identified. With the increased availability of objective methods for hearing assessment in this age group, BOA is used much less than in the past.

2. Visual Reinforcement Audiometry (VRA)

This method is generally used once the child is capable of more accurately localizing a sound source. At approximately six months of age, a child is usually able to turn in response to sound. Using this method, a head turn in response to the test signal - usually a tone or the tester's voice - is rewarded visually, using an animated mechanical toy with lights or other visually appealing stimuli. Sound may be presented through a loudspeaker or through headphones. Depending upon the child's age, threshold or near threshold responses to sound may be obtained.

Limitations of this method would again include habituation to sound, as well as the ineffectiveness of this method for children with significant visual problems. A child who is fearful of the visual reinforcer would also be difficult to assess using this method. By approximately 18 months or less, true threshold responses are expected. Prior to this, developmental norms may be required.

3. Conditioned Play Audiometry

Depending on the child, the use of conditioned play audiometry can begin at or around 2.5 -3 years of age. The child is conditioned to give a certain response each time an auditory signal is presented. The audiologist may have the child put pegs in a pegboard, drop blocks into a bucket, put puzzle pieces into a puzzle, or perform any other task the child finds enjoyable. The stimulus is usually presented through headphones and threshold information can be obtained.

4. Conventional Audiometry

This is the method usually envisioned when the words "hearing test" are used. Children as young as four years of age may be tested using this method. The same or similar method is used for adults. The child is instructed to respond to the softest sound that they can hear in a fashion most interesting to them. The child might raise their hand, clap their hands together, push a button on a handheld device or say "yes" whenever a sound is heard.

Technology exists today to test the hearing sensitivity of a child at any age. To wait until a child reaches a certain age is not only unnecessary, but would not be in the best interest of a child who may have a hearing loss.

**excerpts from this page were taken from Medical Problems in the Classroom, Chapter 9