So, do you have a preference? No, I am not going down a political road! I know better than to bring up politics among friends. Actually, what I want to revisit are the differences between performance for right versus left ears. Recently in the schools there has been a push to examine the eligibility of children with unilateral and minimal hearing loss for special education deaf and hard of hearing services. Research into the impact of unilateral hearing loss and educational performance of children has discussed the adverse effects of unilateral hearing loss making them more likely to have poor academic performance. 1.2 As we look toward including more services for children with unilateral hearing loss, it brings up the issue of specific difficulties associated with right versus left unilateral losses. As audiologists, we are familiar with the triad of symptoms: difficulty hearing on that side, difficulty localizing, and difficulty hearing in noise. We are also familiar with the fact that the degree of hearing loss affects performance; yet, another existing area of research deserves to be examined again. Research has shown specific performance decrements based on whether the loss occurs in the left ear versus the right ear.
A HISTORICAL PERSPECTIVE
In 1986, Fred Bess compiled an issue of Ear and Hearing dedicated to unilateral hearing loss. 3 It brought to light that there were some differences between the performance of children with unilateral hearing loss in the right ear versus the left ear. Results have indicated differences, with the right ear showing more difficulty localizing some frequencies. 4.5 Children with right unilateral hearing loss were noted to more likely fail a grade in school. 6.7 Over time, more researchers found other results indicating additional differences in performance for right ear versus left ear. Cognitive performance was significantly poorer on verbal subtests 8th and performance on interrupted speech tests in background noise for the right unilateral as compared to left unilateral. 9 Physiologic measures indicate a difference in how children localize to speech depending on which ear is involved. 10 For a child with a right unilateral hearing loss, delayed reaction times and stronger physiological responses on the right (ipsilateral) hemisphere were found. 10
Taken together, we have seen several educational outcome differences. Evidence also suggests there are psychosocial differences for children with unilateral hearing loss. 3 Since people respond differently to listening with their right ear versus their left ear, psychosocial measures related to attending to a speaker have been noted to have ear specific implications. The majority of individuals turn the right ear toward a speaker when a conversation is in noise but if a person does not want to attend to something they use the left ear. 11 This suggests that which ear is impaired would impact social interaction.
The information about the differences for individuals with left versus right unilateral hearing loss can help guide management of these children in several ways.
When evaluating a child with a unilateral hearing loss, ear-specific data should be considered. A more in-depth educational evaluation may be needed to examine more than just speech-language abilities and speech in noise testing. Areas of auditory skills such as localization, reaction time and auditory fatigue may give a more complete picture of what impact the loss may have.
Research also suggests the need to add psychosocial measures. The evidence seems stronger toward a child with a right unilateral hearing loss having more difficulty in academics; however, given the diverse nature of problems, it is possible a child with a left unilateral hearing loss will have difficulties that are psychosocial and not traditionally measured in an academic setting.
A multidisciplinary approach may be what is needed to determine what areas are affected for each child. Discussing the characteristics between the losses in different ears with diagnosticians, counselors, speech-language pathologists and teachers of the deaf may be what is needed to tap into the difficulties a child may be experiencing and guide towards appropriate educational modifications and accommodations.
IMPLICATIONS FOR AMPLIFICATION
These ear differences also have implications about amplification for children with a unilateral hearing loss. Unfortunately, I still see children in school wearing nothing for their unilateral hearing loss. It is probably safe to say audiologists agree that amplification is important; however, what is the best solution? There have been discussions of what is the best method of fitting a child with a unilateral hearing loss. 12 Do we use a CROS aid, fit the side with a loss, or maybe use an osseointegrated device? From an educational perspective, performance in background noise is an issue for children with unilateral hearing loss. In that case, the use of hearing assistive technology systems (HATS) may be the offered solution. Factors that affect amplification choices depend on the loss as well as the outcome desired. A CROS has been shown to give some localization abilities but does not necessarily help in noise. A HATS can help in noise but does not help with localization. Based on differences between ears, it may become an issue to get stimulation to the opposite hemisphere. Fitting that ear, if possible, may help the skill development on that side. Bilateral stimulation with an osseointegrated device could be considered as well. However, if noise has a large impact on their performance, the HATS system should be used.
CASE IN POINT
AZ, a girl transferring into the fifth grade, has been in regular education with no accommodations. She has a profound sensorineural hearing loss in her left ear. She has made As and Bs in her classes and there have been no concerns for her speech and language. She has a CROS hearing aid but has reportedly not worn it in a couple of years. Though she does well on assignments, her class participation is not what the teachers expect. When they ask her something, she either does not answer or takes a long time to answer.
An educational audiologic evaluation was performed to see what impact her loss may have. The Screening Identification for Targeting Educational Risk (SIFTER) 13 filled out by her teacher showed “at Risk” for class participation. She reported she could understand the teacher; but did mention on the Listening Inventory for Education – Revised (LIFE) 14 that she sometimes found it difficult to follow the teacher with noise present. When asked, she said she could “hear” the teacher but they “went too fast.”
A Functional Listening Evaluation (FLE) 15 in quiet indicated 96% correct on Pediatric AZ Bio Sentences at a distance of 12 feet. Once noise was added, her score continued to be 92%; however, it took her noticeably more time to answer. Monitoring the response time between the sentence and her response revealed it took five to seven seconds for her to respond while in noise. As a check, testing was performed again in quiet and it took her one to three seconds to provide the response.
AZ was responding with appropriate language skills as you would expect for someone with access to their left hemisphere. The difficulty for her was processing speed. This affected her academic performance when having to follow directions and respond in class. When she was asked about wearing her CROS hearing aid, she said she noticed no difference with or without it on. When she tried a HATS system while listening in noise, her reaction time returned to typical and she said it was “easier” to listen. When questioned about what she meant, she said she did not have to try as hard. Relying solely on percent correct measures, she would have shown no significant difficulty in noise. Considering her reaction time and personal report of benefit, the HATS system is being utilized with her CROS to help her with classroom participation and following directions.
IMPORTANCE OF BEING RIGHT VERSUS LEFT
The perceptual differences between unilateral hearing loss affecting the right versus left ear suggest that services in the schools should be more individualized based on the ear affected, with the goal being to enhance student performance in academic and social situations. This information needs to be passed on to the educational team for identifying children that may need special services in areas not typically assessed in an educational environment. Differential treatment based on the affected ear, as well as the degree of hearing loss, should strongly be considered. In doing so, we can treat the left versus right differences as a united audiologic front and optimize services for these kids as they start receiving additional school support, whether it is equipment, services, or accommodations, that will help these children maximize their academic and social potential.
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