By Dr. Aaron Moberly, Neurotology Fellowship Director, Department of Otolaryngology – Head and Neck Surgery at the Ohio State University
Cochlear implants (CIs) restore a sense of hearing to adults with moderate-to-profound hearing loss. However, broader restoration of communication function requires more than just restoring hearing. Understanding speech through a CI depends on the ability of the “listening brain” to make sense of the degraded auditory input provided through the CI. Fortunately, most adults who receive CIs are able to make sense of this degraded input, but it can take up to two years of practice listening with a CI to reach a plateau in speech understanding. Moreover, for some patients, the process of re-learning to understand speech through a CI is rapid and comes naturally as a result of daily listening, but many (if not all) benefit from intentional, focused aural rehabilitation.
The broad variability in speech understanding among adult CI users and the variable duration of time required to adapt to the degraded input clearly point at differences among individuals in how their listening brains are processing the sound. Even with very similar auditory input through their CIs, individuals’ brains may process the speech information differently, based on differences in previous language knowledge and basic cognitive functions like working memory, processing speed, inhibitory control and nonverbal reasoning. The traditional clinical and research focus of the field has been to try to optimize the quality of the signal coming through the CI by reprogramming the device, or by recommending use of listening accessories. However, it is likely that in many (if not all) cases, there are measures we as clinicians can take to speed up or optimize the way a listener’s brain makes use of the input, particularly through focused aural rehabilitation.
Aural rehabilitation approaches – ideally interdisciplinary approaches among the surgeon, audiologist and speech therapist – comprise a combination of sensory management, instruction on device use, counseling and auditory training. Often, the auditory training component takes a backseat due to logistical issues of time in clinic and billing limitations for audiologists. Patients are frequently left on their own to choose audiobooks or find a useful online training program, which likely does not provide the necessary tailored approach to address their individual rehabilitative needs. Moreover, many individuals do not use any particular active training methods at all, which likely limits or slows their progress post-implant. By emphasizing the importance of auditory training, and by providing a more comprehensive and individualized treatment plan that specifically incorporates training, professionals can support faster and better recovery of communicative functions for adults with CIs.
Auditory training programs
Auditory training programs come in several general forms, from helping the listener learn to identify very basic speech sounds (vowels and consonants) to recognizing complex speech passages in noisy situations. In all cases, the purpose is to encourage the brain to interpret the incoming speech signals more accurately and efficiently. Over the last few years, with the field’s improved understanding of the complex functions of the listening brain, an emphasis has been developed on “auditory-cognitive training.” This method combines various forms of speech perception training with exercises that focus on improving cognitive processing of speech, such as simultaneously exercising working memory or improving processing speed and efficiency. Although studies are only beginning to examine the impact of this broader approach to training on speech understanding, early results are promising, suggesting a powerful means of helping optimize the functioning of a CI user’s listening brain.
About the author: Aaron C. Moberly, MD, works at the Wexner Medical Center at The Ohio State University. He is an assistant professor in the Department of Otolaryngology – Head and Neck Surgery and Neurotology Fellowship Director in the Department of Otolaryngology – Head and Neck Surgery.
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This article expresses the experience and opinions of Dr. Aaron Moberly.