Factor 4 - Early fitting of amplification and ongoing monitoring of its effectiveness are integral to selecting communication strategies to facilitate language development.
To guide our team in identifying evidence shown to support linguistic competence, we followed definitions of evidence described in Evidence-Based Practice in the Early Childhood Field (Buysse & Wesley, 2006). In this book, specific to the field of early childhood, evidence includes: 1) "the best available research" (based on research studies, evaluations, objective measurements of child progress, and systematic literature reviews), 2) practitioner experience or professional and/or family wisdom (based on personal observation, experience, professional or expert consensus, position papers, policy statements and professional judgment), and 3) consumers' values and beliefs, which include personal beliefs, concerns, and expectations of consumers (parents and professionals).
Factor 4 Evidence Summary
The evidence supporting Factor 4 centers on:
- the importance of early fitting of listening technologies, and
- the importance of evaluating and monitoring the role of listening in the development of linguistic competence.
Evidence looking at the cortical development of the auditory system confirms the existence of a time-sensitive period (within the first four years of life, with the most important stage of auditory development occurring before age 2), when central auditory pathways show the maximum plasticity to sound stimulation for optimal benefit from cochlear implantation (Kral & Sharma, 2012). It appears that the end of the optimal period for cortical auditory stimulation occurs at approximately seven years of age when the brain, in the absence of auditory stimulation, has been reorganized and pathways are no longer optimally available to auditory stimulation (Kral & Sharma, 2012). This evidence supports that there is a critical early window when spoken language must be stimulated or delays in spoken language will be difficult, if not impossible, to overcome.
Literature also indicates that while it is possible for a percentage of infants and young children with measurable residual "hearing" (auditory responses) and well-fitted amplification devices to develop linguistic competence via spoken language, a percentage of children may still fail to develop auditory skills necessary for successful oral communication (Geers, 2006; JCIH, 2007). In one studied group of children, it emerged that children with hearing levels in the mild to severe range tended to develop speech understood by most hearing peers and adults by kindergarten, while only a small percentage of children with profound hearing levels approached this same level of competence (Yoshinaga-Itano, 2006).
While the literature cited the advantages of early cochlear implantation for spoken language development for children who are candidates for the technology, it also indicated the variability in spoken language outcomes even with early implantation due to the numerous factors influential to these outcomes (Nicholas & Geers, 2006; Geers & Nicholas, 2013). Noted in the literature is the importance of recognizing the complexity of the auditory mechanism and the considerable variability in spoken language outcomes regardless of hearing levels, use of early amplification, and quality stimulation of spoken language (Blamey, 2003). The varied, evolving, and diverse abilities of each deaf and hard of hearing child highlights the importance of evaluating and monitoring the role of listening in the development of each child's linguistic competence (JCIH, 2007; JCIH, 2013).