1. Introduction
honological awareness skills, as essential components of phonological processes [1], are a strong predictor of success in children’s acquisition of reading and writing skills [2, 3]. There is a high prevalence of hearing loss in children. Moreover, phonological awareness skills play a predictive role in children’s writing and reading success. Awareness of various aspects of language and speech development, including phonological awareness skills, is critical. Thus, understanding the phonological characteristics of Cochlear-Implanted (CI) children is a crucial prerequisite for planning and designing early and appropriate interventions for these children. The effect of language or culture is important on phonological awareness [22, 23]. However, relevant research in Iran is restricted to children aged over 5 years [5, 17, 21], while the development of these skills initiates at the age of 3 years. Accordingly, the present study aimed to examine phonological awareness skills in CI and Typically-Developing (TD) children, aged 4 to 6 years.
2. Materials and Methods
The study population included 25 CI children and 25 normal TD children, aged 4-6 years, who were monolingual Persian speakers. The selected CI and TD children were selected from the Rehabilitation Center of Naqmeh and the Kindergartens in Mashhad, City, Iran, respectively. The parents of children who met the inclusion criteria were explained on the research process; accordingly, their child would have entered the research after providing an informed consent form. To evaluate phonological awareness skills, the Persian Phonological Awareness Tests (Soleimani et al., 2010) were used [18]. This test consists of 10 subtests that measure a total of 3 critical basic phonological awareness skills, i.e., the knowledge of rhyme, phonological awareness, and the knowledge of syllable units. The Persian Phonological Awareness Test was individually performed on each study subject in a quiet room by a speech and language pathologist. Then, the mean scores of each subtest in the study groups were calculated and compared in SPSS by Mann-Whitney U test at the significance level of 0.05.
3. Results 
In total, the phonological awareness skills of 50 Persian-speaking children, including 25 CI subjects (13 boys & 12 girls) with a Mean±SD age of 59.28±6 6.51 months and 25 TD individuals (13 boys & 12 girls) with a Mean±SD age of 56.42±7 7.65 months were assessed in this study. Considering that special subtests were applicable per explored child in the age group of 4 to 4.11 and 5 to 11.5 years, the obtained results were expressed separately.
Comparing the scores obtained by the research groups in this age range of 4 years to 4 years and 11 months indicated that the mean scores obtained by TD children were significantly higher, compared to their CI peers in all subtests of syllable segmentation, homogeneity detection, Rhyme recognition, and phonological composition (P≤0.000) (Table 1). 


According to Table 2, the study subjects in the age range of 5 years to 5 years and 11 months, the TD group obtained significantly higher mean scores in all subtests, compared to their CI counterparts (P≤0.000). 


Comparing the performance of 4- and 5-year-old children signified that the scores of homogeneity and phonological recognition in the TD and CI groups in the age range of 5 years were higher than those in the 4-year-old age group; however, there was no difference in the rhyme diagnosis subtest.
4. Discussion and Conclusion
The present study evaluated phonological awareness skills between CI and TD children. The explored Persian-speaking 4- to 6-year-olds with implant prostheses performed significantly poorer in phonological awareness skills, compared to their TD counterparts. The present research results were consistent with those of previous research on the phonological awareness skills of CI children; thus, CI children performed poorly in this area, compared to their TD peers [17 ,16 ,4 ,3]. The electrical stimuli generated by the cochlear implant prosthesis cannot represent all aspects of speech signals; speech signals are presented to the child as broken spectral signals. Applying incorrect frequency loci in the auditory system and incomplete neural survival further reduce the signal quality provided to CI users [21]. Such limitations in CI children can adversely influence the strength and accuracy of phonological representation, and the development of phonological skills [18]. Thus, despite the increasing development of cochlear implant instruments and technology and the introduction of surgical intervention and early rehabilitation, CI children encounter difficulty learning oral language and phonological awareness skills as a link between spoken and written language; they even experience further challenges with obtaining syntactic-monolingual and other language skills [24, 25]. Any factor associated with hearing loss and experience, speech comprehension, speech production skills, and lexical resource development might contribute to phonological awareness deficits even in children who receive a cochlear implant early. Due to the impact of phonological awareness in achieving writing and reading skills, special sessions should be allocated in the intervention program for CI children to improve these skills among them.
The obtained data suggested that healthy children presented better performance than the CI children in the phonological awareness test. Poor phonological awareness skills in CI children seem to be associated with hearing deprivation before cochlear implantation; thus, it requires to speed up surgery at an early age and the implementation of an effective rehabilitation program.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Research Ethics Committee of Mashhad University of Medical Sciences (Code: IR.MUMS.REC.1396.263).

Funding
This research was supported by the Mashhad University of Medical Sciences (Grant No. 960624).

Authors' contributions
All authors met the standard writing criteria based on the recommendations of the International Committee of Medical Journal Publishers (ICMJP).

Conflicts of interest
The authors declared no conflicts of interest. 

Acknowledgements
We want to thank the Vice-Chancellor for Research and Technology of Mashhad University of Medical Sciences and the cooperation of Naghmeh Rehabilitation Center for their help.


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