Original research paper

Language outcomes for children with cochlear implants enrolled in different communication programs Ennur Yanbay1,2 , Louise Hickson 1,2, Nerina Scarinci 1,2, Gabriella Constantinescu 1,2,3, Shani J. Dettman 1,4 1

HEARing Cooperative Research Centre, Audiology, Hearing and Speech Sciences, The University of Melbourne, Australia, 2Communication Disability Centre, School of Health and Rehabilitation Sciences, The University of Queensland, St Lucia, Australia, 3Research and Innovation, Hear and Say, Australia, 4Department of Otolaryngology, The University of Melbourne, Australia Objectives: The aims of this study were to (a) compare language outcomes in pediatric cochlear implant users enrolled in three different communication programs: sign and spoken language, auditory–oral, and auditory–verbal therapy, and (b) examine factors influencing language outcomes. Methods: Post-implant standard scores on language assessments of receptive vocabulary, auditory comprehension, and expressive communication were collected from files of 42 children with prelingual hearing loss who were implanted by 3;6 years of age. Early intervention history, device details, and demographic information were obtained for each child. Family involvement was evaluated using a rating scale. Results: After adjusting for potential covariates, there were no significant differences in language outcomes across the three groups. Overall, there was a large degree of variability with some children achieving below average scores and others achieving above average scores. Age at diagnosis of hearing loss and family involvement were significantly associated with language outcomes. Conclusion: Regardless of the type of communication approach received, children diagnosed with hearing loss at an early age and children with a high level of family involvement had better post-implant language scores than children diagnosed later and with lower levels of family involvement. These findings emphasize the importance of early diagnosis and highlight the contribution families make to the language outcomes of children with cochlear implants. Keywords: Cochlear implants, Children, Language outcomes, Communication programs, Auditory–oral, Auditory–verbal therapy, Sign language, Family involvement, Early diagnosis

Introduction Since 1985, cochlear implantation has progressed from experimental to standard clinical practice for children with severe and profound hearing loss. Research has produced changes in implant technology and has led to the expansion of implant candidacy to include children younger than 2 years of age. Over time, the audiological criteria have also changed such that children with more residual hearing are now considered as implant candidates. The primary goal of pediatric cochlear implantation is to facilitate spoken language development. Despite the advances in implant technology and the changes to the management of Correspondence to: Ennur Yanbay, Communication Disability Centre, School of Health and Rehabilitation Sciences, The University of Queensland, St Lucia 4072, Australia. E-mail: [email protected]

© W. S. Maney & Son Ltd 2014 DOI 10.1179/1754762813Y.0000000062

hearing loss, language outcomes for children are still highly variable. While some children develop ageappropriate language skills, others demonstrate significant language delays (e.g. Dettman et al., 2007; Geers et al., 2009). In an attempt to understand why children with similar degrees of hearing loss achieve different language outcomes, numerous studies have explored the relationship between language skills and possible predictors such as gender, age at implantation, family involvement, and communication approach. Research examining outcomes for children with hearing loss has demonstrated that girls have superior receptive and spoken language to boys (Easterbrooks and O’Rourke, 2001; Geers et al., 2003c). Another finding in the literature is that early identification of hearing loss provides children a better opportunity to

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develop language skills at par with normally hearing peers (e.g. Calderon and Naidu, 1998; Fulcher et al., 2012; Kennedy et al., 2006; Moeller, 2000; Yoshinaga-Itano et al., 1998). This finding has been a major contributor to the implementation of programs for newborn hearing screening in many countries around the world. However, it must be acknowledged that early identification alone will not lead to better developmental outcomes. It is the timing and quality of the intervention services which follow that result in improved communication outcomes for children with hearing loss (YoshinagaItano, 2004). Following a diagnosis of permanent hearing loss, the Joint Committee on Infant Hearing (2007) recommends that, if families decide to proceed with amplification, infants ‘should be fitted with an amplification device within one month of diagnosis’ ( p. 899). Emphasis is placed on providing immediate access to hearing technology, because auditory deprivation during the early years of life can adversely affect speech and language development. A substantial number of studies have published results on the benefits of early amplification and cochlear implantation (e.g. Boons et al., 2012; Ching et al., 2009; Connor et al., 2006; Dettman et al., 2007; Kirk et al., 2002; Manrique et al., 2004; Sininger et al., 2010). However, not all studies have found results in favor of earlier age at implant. For example, Geers and her colleagues reported that when factors such as non-verbal intelligence and gender were controlled, age at implantation was not a significant predictor of language outcomes (Geers et al., 2003c; Moog and Geers, 2003; Tobey et al., 2003). Other child factors that have been associated with better post-implant language skills are greater preimplant residual hearing, later onset of hearing loss, and more experience with the implant (Geers et al., 2003c; Nicholas and Geers, 2006; Schorr et al., 2008; Szagun, 2001; Tomblin et al., 1999). Furthermore, although research on the effects of unilateral vs. bilateral implants is currently limited, it may be that binaural fitting is associated with improved language skills. As binaural hearing enables a normal-hearing listener to localize the source of sounds and increases their ability to understand speech in noisy environments (Dillon, 2001), it could be expected that bilateral implantation should lead to improved communication outcomes. Today, increasing numbers of children are fitted with a second implant and therefore, it is important to examine the effects of bilateral implantation on language. In comparison to the research on child factors, there is limited literature on the influence of family characteristics on the language development of children with cochlear implants. Since the 1990s, there has

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been a shift in early intervention services from focusing on the child alone to focusing on the family as the client. Parents and families are encouraged to be involved in the service planning and delivery process. The family-centered model has been accepted by both professionals and the wider community as being best practice (Crais et al., 2006). As family-centered practice takes into account each family’s beliefs and the environment in which they live, it is imperative that researchers examine family characteristics of children with hearing loss. In recent years, smaller family size and higher socio-economic status were found to be associated with better language comprehension, production, and verbal reasoning skills in children using cochlear implants (Geers et al., 2003c). Higher maternal education was also reported as a significant contributor to language outcomes at 3 years of age in a population-based longitudinal study examining the outcomes of children with hearing loss in Australia (Ching et al., 2010). Another family characteristic that has been investigated is parental involvement. While parental involvement is considered a fundamental aspect of early intervention, there is relatively little evidence supporting the critical role of parents in children’s habilitation. Moeller (2000) conducted one of the few studies that directly examined the relationship between family involvement and language outcomes for children with hearing loss. Vocabulary and verbal reasoning skills of 112 children with prelingual hearing loss were evaluated. Children were assessed at or near 5 years of age. A rating scale was developed to measure the quality of family involvement in the intervention program. The relationship between language scores and a number of variables was examined including degree of hearing loss, age at enrolment in early intervention, non-verbal intelligence, and family involvement. Analyses revealed that family involvement was the strongest contributor to positive language outcomes. The next most important variable was age at enrolment in intervention, which was negatively correlated with language skills. Thus, Moeller concluded that successful language outcomes can be achieved when intervention is initiated at an early age and parents are actively involved in the intervention program. In addition to child and family factors, researchers have examined educational factors that may influence language outcomes in children with hearing loss. Communication mode or type of communication approach, in particular, is a variable that has received much attention from parents, educators, and researchers alike. Since the mid-eighteenth century, a number of communication approaches have been advocated for helping children with hearing loss acquire language and communication skills (Moores,

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2010). The most common approaches are: (a) auditory–oral (AO); (b) auditory–verbal therapy (AVT); (c) total communication; and (d) the bilingual–bicultural approach. AO and AVT approaches are similar in that both aim to assist children develop spoken language and enable full integration into mainstream society. Both promote early diagnosis of hearing loss, followed by immediate and optimal amplification. They place an emphasis on the consistent use of hearing technology. However, they differ in that the AO approach encourages the use of lip-reading, facial expression, and naturally occurring gestures. AVT, on the other hand, de-emphasizes the use of visual cues (Estabrooks, 2006). Total communication is a multisensory approach which is practiced widely around the world. It aims to offer the most appropriate oral and visual codes according to individual needs (Lynas, 1999). The signing in total communication is a contrived sign system (e.g. Signed English) that was designed to be used simultaneously with a spoken language. It is not a natural sign language (Lynas, 2005). A natural sign language, such as the Australian Sign Language (Auslan), is one that has evolved within a Deaf community and has its own unique grammar and word order. In recent years, some early intervention centers have moved towards the use of natural sign languages as part of bilingual–bicultural education, which involves teaching a natural sign language as the child’s first language and spoken/written English as their second language (Komesaroff, 2001). In Australia, bilingual–bicultural educational programs were first established in the 1990s (Komesaroff, 2001), and later Auslan was introduced at the early intervention level (Napier et al., 2007). Although Auslan was traditionally taught as the first language of instruction, with the advent of universal newborn hearing screening and advances in cochlear implant technology, alternative conceptualizations of bilingual–bicultural programs have emerged (Mayer and Leigh, 2010). Today, some children learn to listen and speak first and acquire Auslan as a second language, while others learn to speak and sign concurrently. Children may be learning Auslan by parental design, or because of circumstances such as failing to achieve desirable outcomes in a strictly oral program (Mayer and Leigh, 2010). Literature supporting any of these approaches is limited (Gravel and O’Gara, 2003), and research investigating the association between language outcomes and communication mode has produced mixed results. Some studies have demonstrated that children who use oral communication are more likely to achieve better post-implant language scores than children who use total communication. For example, after examining the vocabulary development of 60 children

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with cochlear implants, El-Hakim and colleagues (2001) found that oral communication was a significant predictor of gains in receptive vocabulary. The results of this study, however, should be interpreted with caution because only 8 of the 60 participants used total communication. Geers and colleagues recognized that future studies in this area needed to include a greater number of participants, as well as controlling for factors such as gender and degree of hearing loss. They administered a battery of speech perception, language, and reading tests to 181 children who were implanted by 5 years of age (Geers, 2002; Geers et al., 2003a, 2003b; Tobey et al., 2003). Children were divided into two groups based on the communication training they received: oral communication (n = 92) and total communication (n = 89). The results showed that children who consistently used oral communication achieved better scores on all outcome measures than children who used total communication. In contrast to research demonstrating an advantage for children using oral communication, one study reported an advantage for children using total communication (Connor et al., 2000), and others reported no significant difference in language skills between children educated in oral vs. total communication programs (Kirk et al., 2002; Robbins et al., 1999). Although these studies provide valuable findings, one could argue that their participants no longer represent current clinical practice in pediatric implantation as they were fitted with implants over 10 years ago. Hearing technology is advancing rapidly and implant criteria are constantly evolving. Today, infants with greater amounts of residual hearing are fitted with cochlear implants and children are receiving intervention at much younger ages. Therefore, further research is needed to explore the effects of communication approach on the language skills of children who have received implants in recent years. Parents are interested in determining which communication approach will maximize their child’s chances of achieving age-appropriate language skills, and clinicians are obligated to provide evidencebased information about communication choices. Existing research in this area, however, is limited because many of the studies examining communication approach did not control for possible confounding factors. Thus, it is difficult to attribute findings to the communication program. Furthermore, past studies examining communication approach have tended to dichotomize this variable into oral communication and total communication, but there are further sub-categories within both these approaches. For example, within oral communication, there are two main approaches: AO and AVT. In many states of Australia, there are clear methodological

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differences between AVT and AO practices. Hence, when evaluating the outcomes of Australian children, it is important to examine these groups separately. This research can provide parents and educators with additional information, which may help to further determine children’s needs. Moreover, there is little or no research on outcomes for children with cochlear implants enrolled in early intervention programs using both a natural sign language and a spoken language. Consequently, the outcomes for children in these programs remain poorly understood. The present study retrospectively examined the language outcomes of a group of Australian children with cochlear implants enrolled inAO, AVT, and sign and spoken language (SS) programs. Children in the SS group used both a natural sign language and spoken English for communication. Participants were selected based on a very specific set of criteria such

Table 1

that the sample would be relatively homogenous. The following research questions were investigated: 1. Are there differences in outcomes for children with cochlear implants enrolled in AO, AVT, and SS programs? 2. Is there a relationship between language skills and factors such as gender, pre-implant hearing, age at diagnosis of the hearing loss, age at hearing aid fitting, age at implant, number of implants, duration of cochlear implant use, age at enrolment into the communication program, length of participation in the communication program, socio-economic status, and family involvement?

Methods Participants A retrospective cohort study was conducted to examine the language outcomes of 42 pediatric

Participant characteristics for children enrolled in AO, AVT, and SS communication programs Audiological history Age at diagnosis* (years)

Age at hearing aid fitting (years)

Age at cochlear implant (years)

Hearing loss† (dB HL)

Group

Mean (SD)

Range

Mean (SD)

Range

Mean (SD)

Range

Mean (SD)

AO (n = 14) SS (n = 10) AVT (n = 18)

0.42 (0.38) 0.68 (0.67) 0.34 (0.44)

0.04–1.17 0.04–1.75 0.04–1.50

0.54 (0.38) 0.80 (0.68) 0.43 (0.44)

0.17–1.17 0.13–2.10 0.04–1.67

1.21 (0.72) 1.53 (0.80) 1.04 (0.48)

0.53–3.30 0.65–3.18 0.58–2.14

110.09 (10.44) 110.75 (13.48) 97.55 (9.17)

Range 85–124 88–125 84–118

Child and family characteristics Gender Group AO (n = 14) SS (n = 10) AVT (n = 18)

Age at entry to the program (years)

Socio-economic status

Family involvement

Male

Female

Mean (SD)

Range

Low to mid

High

Lower level

High level

7 4 8

7 6 10

0.88 (0.96) 1.33 (1.08) 0.66 (0.67)

0.07–2.84 0.06–3.05 0.09–2.16

8 7 8

6 3 10

5 7 5

9 3 13

Chronological age, implant experience, and length of intervention‡ at PPVT§ Age (years)

Duration of implant use (years)

Length of intervention (years)

Group

Mean (SD)

Range

Mean (SD)

Range

Mean (SD)

Range

AO (n = 14) SS (n = 9) AVT (n = 14)

4.86 (1.16) 4.65 (1.18) 4.78 (1.19)

2.77–6.40 3.00–6.33 2.77–6.63

3.66 (0.95) 3.14 (1.08) 3.70 (1.13)

2.02–5.08 1.11–4.87 2.03–5.20

3.98 (1.00) 3.33 (0.97) 4.05 (1.18)

2.59–5.47 1.44–5.04 2.53–6.09

Chronological age, implant experience, and length of intervention at PLS-4 Age (years)

Duration of implant use (years)

Length of intervention (years)

Group

Mean (SD)

Range

Mean (SD)

Range

Mean (SD)

Range

AO (n = 12) SS (n = 9) AVT (n = 18)

4.60 (1.47) 4.31 (1.68) 3.64 (1.16)

1.77–5.92 1.92–6.46 2.11–6.63

3.55 (1.34) 2.72 (1.59) 2.59 (0.97)

1.03–5.08 0.51–4.87 1.50–4.49

3.85 (1.36) 2.90 (1.44) 2.92 (1.01)

1.59–5.47 0.86–5.04 1.48–5.30

Note: *Some children were confirmed to have a bilateral severe–profound hearing loss over 12 months of age, but their loss was suspected earlier. † Hearing loss figures are for pre-implant pure tone average thresholds (PTA) at 500 Hz, 1 kHz, 2 kHz and 4 kHz. For the purpose of calculating PTA, hearing thresholds beyond the limits of the audiometer were recorded as being 5 dB above the audiometer limit (Ching et al., 2001). ‡ Length of intervention is the duration of participation in the communication program. § Due to the retrospective nature of this study, there was some missing data. Post-implant PPVT scores were available for 37 of the 42 children, and post-implant PLS-4 data were available for 39 children. Some children had both PPVT and PLS-4 data (n = 34), while others had only PPVT (n = 3) or only PLS-4 (n = 5) data in their clinical files.

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cochlear implant users. Participant characteristics are presented in Table 1. Data for the 42 children were collected from two agencies: an early intervention center in the state of Queensland and a cochlear implant clinic in the state of Victoria, Australia. All children in Queensland received intervention through an AVT center, whereas children who attended the cochlear implant clinic in Victoria were enrolled in either an external AO or bilingual center. The three centers were described as embracing a family-centered model whereby staff work in partnership with parents and primary caregivers. Children were selected for inclusion according to the following criteria: (a) born between January 2002 and December 2008; (b) a bilateral severe and/or profound sensorineural hearing loss, which was suspected or identified by 12 months of age; (c) cochlear implantation before turning 4 years of age; (d) fitted with a multichannel Cochlear™ implant and used the ACE speech processing strategy; (e) enrolled in the communication program for at least 10 months; (f ) monolingual English speakers; and (g) no diagnosed developmental or medical conditions that would be expected to affect communication development. All children from the early intervention center and cochlear implant clinic who met these criteria were included in the analyses, except for identified outliers (see the Statistical analysis section) and those who had no formal post-implant language assessments. Two of the 42 participants had parents with a significant hearing loss. Both these participants used spoken English and Auslan for communication. Etiologies of hearing loss were genetic (n = 16), cytomegalovirus infection (n = 2), ototoxicity (n = 1), meningitis (n = 1) and unknown (n = 22). The majority of children (n = 28) were diagnosed with a hearing loss at or under 6 months of age. They were all fitted with digital hearing aids prior to receiving their cochlear implants. Their hearing aids were fitted and managed by Australian Hearing, the national service provider for children with hearing loss. Children were referred for possible cochlear implantation when it was deemed they were not gaining adequate benefit from hearing aids. Following the candidacy evaluation process, 11 children received a unilateral implant, 25 received sequential implants, and 6 received simultaneous implants. Twenty-two children were implanted under the age of 12 months, 15 were implanted at 1–2 years, three were implanted at 2–3 years, and two were implanted at 3–3;4 years of age. Participants received their first implant(s) between 2003 and 2009 and were fitted with the Nucleus-24 (n = 7) or the Freedom (n = 35) implant device. In Australia, implant recipients have access to device upgrades as new products are

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launched. Therefore, all 42 children used similar levels of implant technology. Children in the AO group Participants in the AO group (n = 14) were enrolled in one of the Australia’s largest early intervention centers for children with hearing loss. This center follows a natural AO approach. The rationale for a natural AO approach is that children with hearing loss have special needs, but they are not different from other children. Thus, advocates of this approach encourage parents and professionals to provide children with hearing loss the same kind of learning environment as they would for children with normal hearing (Clark, 2007). As children with normal hearing use visual cues to communicate with others, children enrolled in this program are encouraged to use lipreading, facial expressions, and naturally occurring gestures to support their oral communication. Two of the 14 children were previously enrolled at another center in a SS program, but had been enrolled in the AO program for over 3 years at the time of testing. Children at this AO center have individual face-toface therapy sessions, which require family attendance. The sessions may be on a weekly or monthly basis depending on each family’s needs. The center also offers playgroups, various early childhood programs, and mainstream kindergartens for 3 and 4 year olds. Children in the AVT group All children in the AVT group (n = 18) received therapy from a non-profit organization that provides audiology services, a cochlear implant program, and AVT to children with hearing loss. One child previously received AVT at an early intervention center in another Australian state, before he and his family moved and enrolled in the Queensland program. The Queensland program is available to children from the time of diagnosis until the time they start attending grade one of primary school. Parents receive support and guidance through weekly or monthly AVT sessions. Parents are considered the clients in this program and are required to attend all therapy sessions with their child. Lessons are carried out exclusively through listening and spoken language by certified auditory–verbal therapists who coach parents to teach their child to communicate via hearing alone. Therapists are guided by the 10 principles of AVT endorsed by the Alexander Graham Bell Academy for Listening and Spoken Language (2007). A program is regarded as using an auditory–verbal approach only when all 10 principles are followed (Alexander Graham Bell Academy for Listening and Spoken Language, 2007). The center offers parent education classes, playgroups, and kindergarten type

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activities to all families who are enrolled in the early intervention program. Children in the SS group The 10 children in the SS group were reported as using both spoken English and Auslan to communicate with others. Although Auslan is a natural sign language, the term bilingual–bicultural was not used to refer to these children because many of them did not learn Auslan as their first language. Instead, the authors used the term ‘sign and spoken language’ to encompass all possibilities that involve the use of Auslan and spoken English. The amount of emphasis on SS varied across the children. At home, some children (n = 3) used spoken English for the majority of communication with occasional signing, and others (n = 7) used both spoken English and Auslan (i.e. an equal emphasis of sign language and spoken communication). During therapy, three children used spoken English for the majority of communication with occasional signing, five used both spoken English and Auslan, and two used spoken English only. All but two children were enrolled in a home visit program, which aims to facilitate early communication and language skills through listening, speaking, and signing. The program is funded by the government and is offered to children who have a confirmed bilateral hearing loss and are eligible for hearing devices from birth to school entry. Home visits are typically fortnightly and parents have access to an interdisciplinary team of speech–language pathologists, teachers of the deaf, deaf educators, psychologists, and social workers, as needed. The two children who were not enrolled in the home visit program were born to native Auslan users with a significant hearing loss. These children used spoken English during therapy and were exposed to spoken English and Auslan at home. As the children had exposure to fluent Auslan in their home environment, the parents chose to receive early intervention services that would place an emphasis on the development of their spoken English skills.

Measures A number of measures were collected from clinical files to represent the following areas: (a) receptive vocabulary skills; (b) auditory comprehension (AC) and expressive language skills; and (c) socio-economic status. A rating scale was used to measure the quality of family involvement. The details of these measures are described below. Language assessments All language assessments were administered and scored by certified speech–language pathologists or

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auditory–verbal therapists according to manual instructions. While clinicians administered assessments using spoken English only, for children in the SS group, both spoken and signed responses were accepted. Peabody Picture Vocabulary Test The Peabody Picture Vocabulary Test (PPVT) is a measure of single word receptive vocabulary for individuals aged 2;6 to 90+ years. A number of versions of the PPVT have been developed since it was first released. Scores obtained on the PPVT-R (Dunn and Dunn, 1981), PPVT-III (Dunn and Dunn, 1997), and PPVT-4 (Dunn and Dunn, 2007) are highly correlated with one another and thus, data from all three versions were used in this study. Children’s most recent post-implant PPVT standard scores were analyzed. Standard scores were used because they are corrected for chronological age, and provide information about performance relative to the average score of the normative sample (M = 100, SD = 15). The fourth edition of the Preschool Language Scale The fourth edition of the Preschool Language Scale (PLS-4) (Zimmerman et al., 2002) is a standardized test, which assesses AC and expressive communication (EC) skills in children from birth to 6 years 11 months of age. Children’s most recent post-implant PLS-4 AC and EC standard scores were collected for use in the analyses. Index of Relative Socio-economic Advantage and Disadvantage Socio-economic Indexes for Areas is an Australian product that is created from the 2006 census data (Australian Bureau of Statistics, 2006). There are four indexes and each summarizes different characteristics of people residing in an area. Indexes are provided for collection districts, statistical local areas, local government areas, postal areas, and state suburbs. This study used postcode data to attain each child’s Index of Relative Socio-economic Advantage and Disadvantage (IRSAD) decile score as a measure of socio-economic status. The IRSAD is constructed from 21 census variables, including low or high income, occupation, and education. IRSAD decile scores range from 1 to 10 where a high score indicates a relatively advantaged area and a low score indicates a relatively disadvantaged area. Here, advantage refers to having high access to economic resources and being able to participate in the society. Family Participation Rating Scale The Family Participation Rating Scale (FPRS) was developed by Moeller (2000) to characterize the quality of family participation in early intervention

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programs for children with hearing loss. Early interventionists are asked to assign a single global rating for each family on a scale of 1–5, where 1 = limited participation, 2 = below average participation, 3 = average participation, 4 = good participation, and 5 = ideal participation. The five scales are represented by a description of characteristics that take into account issues such as family involvement in therapy sessions, the family’s adjustment to the child’s hearing loss, and parent–child communication.

Procedure Prior to commencing data collection, approval was received from The University of Queensland, an early intervention center, and a hospital human research ethics committee. Both the early intervention center and the cochlear implant clinic had established databases of participant information and parents had given written consent for the use of their child’s data in research projects. Initially, a search of the databases was performed to identify children who met the inclusion criteria. Once all potential participants were identified, information on the following variables was obtained from clinical files: gender, pre-implant hearing thresholds, age at diagnosis of the hearing loss, age at hearing aid fitting, age at implant, number of implants, duration of cochlear implant use, age at enrolment into the communication program, and length of participation in the communication program. In addition, information on etiology of hearing loss, implant device, communication mode, postal area codes, and post-implant PPVT and PLS-4 data was collected. A list of the participants was then provided to the early intervention center and the cochlear implant clinic, and clinicians (speech–language pathologists, auditory–verbal therapists, and audiologists) who worked closely with these children were asked to retrospectively rate the level of family involvement they experienced over the pre- and post-implant period. For each participant, two clinicians assigned independent ratings using Moeller’s FPRS (2000). Clinicians’ scores were compared for inter-rater reliability. Ratings were included in the analyses if there was exact agreement between the two clinicians, or if there was a one point deviation between the two ratings in which case the average of the two scores was considered for the statistical analyses. Exact agreement was found for 35 of the 42 children. For the remaining seven children there was a one point deviation between the two judgments.

Statistical analysis The primary aim of this study was to examine and compare post-implant language outcomes for children

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who were enrolled in AO, AVT, and SS communication programs. Dependent variables were post-implant PPVT, PLS-4 AC, and PLS-4 EC standard scores. The one-way analysis of covariance (ANCOVA) was used to compare language outcomes across the three groups of children after adjusting for the effects of potential covariates. A covariate should correlate significantly with the dependent variable, but should not correlate strongly with other covariates. Thus, prior to performing the ANCOVA, a series of analyses were conducted to identify suitable covariates. Based on the literature, the present study collected data on 11 variables that may influence language outcomes in children with hearing loss. These were gender, age at diagnosis of the hearing loss, pre-implant unaided hearing in the better ear (hearing loss), age at hearing aid fitting, age at cochlear implant, duration of cochlear implant use, number of implants, age at enrolment into the communication program, length of participation in the communication program, socio-economic status, and family involvement in the intervention program. A series of ANOVA tests showed that there were no significant differences ( p > .05) amongst the three groups of children for any of the continuous variables listed in Table 1, except hearing loss. Post-hoc comparisons using the Tukey HSD test indicated that the mean hearing loss score of the AO and SS groups was significantly greater than the mean of the AVT group (refer to Table 1 for mean scores). To facilitate better interpretation of statistical results, socio-economic status and family involvement were evaluated as dichotomous variables. Children with an IRSAD decile of 1 to 7 were categorized as having low to mid socio-economic status and those with a decile of 8 to 10 were categorized as having a high socio-economic status. For family involvement, children with a rating of 5 were categorized as having a high level of family involvement and those with a rating of .05. Standardized residuals were examined and found to be within normal limits. Table 4 presents the mean and standard deviation of PPVT scores for each of the groups, as well as the percentage of children scoring within or above one standard deviation of the normative mean (i.e. standard score of ≥ 85). There was a significant relationship between PPVT scores and family involvement, where family involvement accounted for 33.3% of the variance in PPVT performance. Children with a high level of family involvement had higher post-implant PPVT standard scores. Furthermore, as illustrated in Fig. 1, there was a large degree of variability in PPVT scores with some children achieving below average results (standard score of 115).

Table 2 Descriptive statistics of post-implant PPVT scores and independent samples t-test results for dichotomous variables

n

Results Post-implant PPVT scores

8 6

M

AVT

Range

Variables that demonstrated a significant ( p < .05) relationship with post-implant language scores were then selected as covariates for the one-way ANCOVA. All data were analyzed using the Statistical Package for Social Sciences Version 20.0 (SPSS).

45–84 76–124

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Table 3 Correlation coefficients among all continuous variables and post-implant PPVT standard scores (n = 37)

Age Diag Age HA Age CI Age Enrol Duration CI Exp PTA

PPVT

Age Diag

Age HA

Age CI

Age Enrol

Duration

CI Exp

−0.25 −0.28 −0.27 −0.19 0.02 0.01 −0.17

0.98* 0.68* 0.64* −0.12 −0.02 0.00

0.69* 0.68* −0.14 −0.01 0.01

0.76* −0.14 −0.17 −0.24

−0.32 0.07 −0.16

0.81* −0.04

−0.06

Note: *p < .01. Abbreviations: PPVT = post-implant PPVT standard scores; Age Diag = age at diagnosis of hearing loss; Age HA = age at hearing aid fitting; Age CI = age at cochlear implant; Age Enrol = age at enrolment into the communication program; Duration = duration of participation in the communication program; CI Exp = amount of cochlear implant experience; and PTA = pre-implant unaided hearing in the better ear. Table 4 Descriptive statistics for post-implant performance on the PPVT and PLS-4 Post-implant performance on the PPVT Group

n

Adjusted mean*

Mean

Standard deviation

Range

% of Children with a standard score of ≥85

AO SS AVT

14 9 14

87.49 89.30 88.30

88.43 83.33 91.14

13.99 15.78 20.98

55–111 55–114 45–125

64.29 44.44 57.14

Group

n

Adjusted mean**

Mean

Standard deviation

Range

% of Children with a standard score of ≥85

AO SS AVT

12 9 18

87.74 81.57 88.00

89.92 73.11 90.78

11.78 19.83 22.81

71–115 50–102 55–138

75.00 33.33 55.55

Post-implant performance on the PLS-4 auditory comprehension measure

Post-implant performance on the PLS-4 expressive communication measure Group

n

Adjusted mean***

Mean

Standard deviation

Range

% of Children with a standard score of ≥85

AO SS AVT

12 9 18

91.60 82.29 89.51

93.67 75.11 91.72

8.82 17.79 20.89

79–105 50–94 50–1–7

83.33 44.44 61.11

Note: *The adjusted mean is the estimate of the group mean after the effect of the covariate has been statistically removed. Here, the mean was adjusted using ANCOVA for two covariates: socio-economic status and family involvement. **The mean was adjusted using ANCOVA for four covariates: age at diagnosis, age at cochlear implant, socio-economic status, and family involvement. ***The mean was adjusted using ANCOVA for three covariates: age at diagnosis, age at cochlear implant, and family involvement.

Figure 1

Post-implant PPVT standard scores for 37 children with cochlear implants.

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70.00 98.77 5 13 50–102 75–98 19.83 11.59 66.00 87.33 6 3 71–85 84–115 7.21 10.88 79.00 93.56

7.86 13.90

50–102 55–138 Note: *Both children had a standard score of 85.

70.21 95.52 14 25

15.15 16.92

80.50 94.12 22 17

16.05 22.93

50–117 50–138

2.18

4.65

0.04

.05. Likewise, a comparison of unadjusted means showed no significant difference across the three groups on post-implant PLS-4 AC scores, F(2, 36) = 2.77, p > .05. Standardized residual values were found to be normal. Consistent with the PPVT findings, there was a significant relationship between family involvement and PLS-4 AC performance, where family involvement explained 24.4% of the variance. However, in addition to this, age at diagnosis was also significantly related to PLS-4 AC scores and accounted for 13.9% of the variance. A considerable degree of variability was observed both within and across the three groups (Fig. 2A).

Range

Post-implant PLS-4 AC scores

57–84 55–138

Language of children with cochlear implants

n

Yanbay et al.

Yanbay et al.

Language of children with cochlear implants

Table 6 Correlation coefficients among all continuous variables and post-implant PLS-4 AC standard scores (n = 39)

Age Diag Age HA Age CI Age Enrol Duration CI Exp PTA

PLS-4 AC

Age Diag

Age HA

Age CI

Age Enrol

Duration

CI Exp

−0.51* −0.50* −0.43* −0.30 −0.12 −0.13 −0.14

0.98* 0.68* 0.64* −0.05 0.04 0.00

0.69* 0.68* −0.04 0.08 0.01

0.76* −0.00 0.01 −0.24

−0.14 0.20 −0.16

0.88* 0.07

0.06

Note: *p < .01. Abbreviations: PLS-4 AC = post-implant PLS-4 AC standard scores; Age Diag = age at diagnosis of hearing loss; Age HA = age at hearing aid fitting; Age CI = age at cochlear implant; Age Enrol = age at enrolment into the communication program; Duration = duration of participation in the communication program; CI Exp = amount of cochlear implant experience; and PTA = pre-implant unaided hearing in the better ear.

Figure 2 (A) Post-implant PLS-4 AC standard scores for 39 children with cochlear implants. (B) Post-implant PLS-4 EC standard scores for 39 children with cochlear implants.

Age at hearing aid fitting was not included because it was so highly correlated with age at diagnosis. After adjusting for the three covariates in the ANCOVA, there was no significant effect for communication program, F(2, 36) = 0.91, p > .05. Once again, standardized residuals were examined and found to be within normal limits. The means and standard deviations of post-implant PLS-4 EC standard scores are displayed in Table 4. Of all the covariates, only family involvement was significantly associated with PLS-4 EC performance, accounting for 19.8% of the variance. Almost half of the SS children, most of AO children, and just over half of the AVT children achieved PLS-4 EC scores that were equal to or greater than a standard score of 85 (Fig. 2B).

Discussion Although previous research had investigated possible child, family, and educational factors that may be associated with language skills (e.g. Connor et al., 2000; Geers et al., 2003c; Schorr et al., 2008), the present study is unique in that it included participants

who were more representative of the current population of Australian children with hearing loss. That is, the majority of participants were diagnosed with hearing loss within the first few months of life and received cochlear implants at much younger ages compared to children in previous studies. The primary aim of this study was to compare post-implant language outcomes of these children who were enrolled in AO, AVT, and SS communication programs. The results showed no significant differences in language scores across the three groups of children, once the effects of potential covariates were accounted for in the analyses. This finding supports the results of Kirk et al. (2002) who investigated the influence of age at implant and communication mode on the speech and language skills of 106 children with prelingual hearing loss. Kirk and colleagues compared pre-implant and postimplant outcomes for 56 children using oral communication to 50 children using total communication. While children in the oral communication group had significantly better spoken word recognition scores,

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50–95 68–127 71.00 99.69 5 13

85.25 96.90

50–94 69–94

8 10

18.47 13.89

50–94 50–88

70.17 85.00

16.90 26.87

6 3

76.86 69.00

79–105 85–105

7 2

14.22 6.61

79–105 85–105

88.67 95.33

9.21 8.53

50–105 68–127 74.43 96.36 14 25

17.35 13.99

84.68 93.41 22 17

17.40 19.09

50–116 50–127

1.49

4.31

0.15