Enhancing VRA Testing in Young Children
By Marc Iskowitz
The challenges of testing children between the ages of 6 months and 2 1/2 years make visual reinforcement audiometry (VRA) a necessary component of pediatric assessment. By adopting certain improvements to their VRA technique, such as adding more reinforcers, clinicians can improve the effectiveness of this measure.
“People who are doing a lot of pediatric testing, whether for hearing aid fittings or for evaluations, need to consider multi-level or multi-tiered boxes in the visual reinforcement unit,” said Maureen Cassidy Riski, MEd, CCC-A, pediatric audiology coordinator for Atlanta Ear, Nose and Throat Associates in Atlanta, GA. This technique involves using two to three different mechanical toy reinforcers that are brightly colored and highly animated.
Switching among the three enhances the impact of the reinforcement because of its novelty and uncertainty (“A Normative Picture of Infant Auditory Development,” Seminars in Hearing, Vol. 5).
“The more toys for the children to see, the better the chance of them being conditioned, and the more likely you are to get a response,” Riski noted. Increasing the number of toys also increases the element of surprise for subjects.
Riski has added two toy compartments to both of the visual reinforcement units in one of the three sound booths at her facility. “It’s important to have a multi-tiered system because you can maintain the interest level of the child for a longer period of time,” she said.
Despite these benefits, many facilities only use one reinforcer.
“It’s hard for a 6-month-old to turn his or her head and look up to see the box,” Riski explained. “With the multi-tiered system, reinforcement can be more at the patient’s eye level.”
If a child has a motor impairment that precludes viewing all three toys, clinicians can activate just the middle position (“Behavioral Assessment of Auditory Function,” Seminars in Hearing, Vol. 10, No. 3).
Riski prefers placing a visual reinforcement unit on either side of the child to elicit a response dependent on the particular ear stimulated. “In this way we can see how each ear is responding,” she noted.
“The three-tiered system is excellent,” agreed Jolie Fainberg, MA, CCC-A, coordinator of audiological services at Egleston Health Care System in Atlanta. A new facility being built by her company will incorporate this concept in its VRA test suite.
More stimulation will keep children occupied longer, Fainberg stated. “With children 6 months old, you have 10-12 minutes or less to do the test because the child will get fussy. You have to work fast, but you also have to be accurate.”
To keep children occupied during VRA, Fainberg likes to have a parent or other person in the test booth to assist her. The assisting person should wear a bone-conducting headband in order to hear the auditory stimuli and reinforce the child when necessary. Her assistants sometimes use a headset, not to hear auditory stimuli but to communicate and take cues from the audiologist.
If no one is available to assist in the testing process, an electronic distractor, such as an animated dog in a Plexiglas box mounted on the wall, can be used.
Using ear inserts is important in delivering auditory stimulation to children, Riski said, especially if a parent has concerns about hearing loss due to speech and language delays and separate ear information is needed. Without sending individual information to each ear, the VRA becomes a sound field test, which reflects a better ear response and will not detect a unilateral impairment.
Riski begins her VRA technique with brief speech stimuli, such as “uh-oh,” or “ba, ba.”
“Most people start out with speech because it’s well known to the child and might get their attention,” she said. In her preliminary conditioning trials, she uses louder stimulus levels and decreases decibel level to search for thresholds.
Fainberg starts at 30 dB with speech and increases the loudness if the patient does not respond. “If they respond I go down and then do a threshold search from there,” she noted.
Fainberg said the classic response to look for is the head turn. “If the child has some reason to respond in another way, you want it to be a stimulus-locked response.”
Other ways that children respond are by putting their hands over their face and blinking their eyes. However, “you have to be careful with other responses,” the audiologist cautioned, “otherwise VRA turns into behavioral observation audiometry [BOA].”
BOA involves providing loud sounds from a speaker and making subjective judgments about the subject’s reactions. A child may stop using the chosen response not because he or she cannot hear but because they have habituated to the stimulus.
To avoid falling into this trap, audiologists should remember that VRA is an operant conditioning task. “If the subject is turning their head every five seconds, the test is not real,” said Fainberg, adding that BOA is appropriate when used in conjunction with auditory brainstem response (ABR) and otoacoustic emissions (OAE) testing.
Confirmation of a hearing loss requires both behavioral and physiological testing. Behavioral measures like VRA provide threshold responses at different frequencies.
The most frequently used physiological test is the standard click-evoked ABR. But this method only tests the 2-4 kHz frequency range. According to Martha Miller, MCD, CCC-A, director of audiology at Atlanta Ear, Nose and Throat Associates, reliable frequency-specific threshold information can be obtained by using Blackman-filtered toneburst stimuli in addition to click stimuli.
When OAE testing is abnormal and reliable behavioral audiometry cannot be obtained, toneburst ABR can provide frequency-specific information, Riski added.
It is important to note that behavioral testing can identify severe to profound hearing loss not detected by ABR. “ABR is a test of hearing sensitivity only,” Riski noted. “It does not tell us how the patient understands sound.”
Behavioral tests reveal how children use their hearing and whether they respond to sound, added Fainberg. “You can do electrophysiological tests and everything could come out normal; but if the child doesn’t respond to sound, we won’t know the problem.”
The need for both behavioral testing and physiological evaluation is especially pressing in the pediatric population, she said. “We want to diagnose a hearing loss as early as possible, because we’ve found that early intervention makes a big difference. The sooner we can fit hearing aids on children who need them, the better they do in their speech and language development.”
Although audiologists cannot use VRA on children younger than 6 months because of their inability to turn their heads in response to auditory stimuli, ABR and OAE are viable tools to use on infants of any age.
Children older than 2 1/2 years are probably suitable for play audiometry, a conditioning task like VRA that involves more complex responses, such as throwing a block into a bucket upon hearing auditory stimuli.
“We’re increasingly trying to find ways to test children earlier and earlier,” Fainberg said.
For More Information
Jolie Fainberg, Egleston Health Care System, 1405 Clifton Rd. NE, Atlanta, GA 30322; (404) 315-2454
Maureen Cassidy Riski, Atlanta Ear, Nose and Throat Associates, 5555 Peachtree Dunwoody Rd., Atlanta, GA 30342; (404) 255-2918