Linguistic and Metalinguistic Profiles of PersianSpeaking Children with Hearing Impairment: A Systematic Review of Observational Studies

Abstract

Background and Aim:  Numerous studies have investigated the linguistic characteristics of Persian-speaking children with hearing impairment. Given the variability of findings across these studies, a systematic review is required to both identify research gaps and synthesize existing results. This systematic review aimed to answer the following question: in Persianspeaking children with hearing impairment compared to typically hearing Persian-speaking children, what is the profile of linguistic skills (phonology, morphosyntax, semantics, pragmatics) and metalinguistic skills (phonological awareness, syntactic awareness, semantic awareness)?

Recent Findings: Persian-speaking children with hearing impairment experience significant delays across most linguistic domains, particularly in phonetics/phonology (55% of studies), morphosyntax (16%), and semantics/pragmatics (13%). The most consistent deficits were observed in vowel production and perception, phonological awareness, grammatical omissions, tense marking errors, and comprehension of non literal meanings. Children with cochlear implants outperformed hearing aid users, and early implantation (before age 2) was associated with more favorable outcomes.

Conclusion: Persian-speaking children with hearing impairment demonstrate significant and persistent delays in both linguistic and metalinguistic skills compared to typically hearing peers. Early cochlear implantation and linguistically rich educational environments (e.g. mainstream schools) are associated with better language outcomes. Clinically, comprehensive language assessments should include both receptive and expressive skills, with targeted interventions focusing on phonological awareness, morphosyntax, and pragmatic abilities. Future research should prioritize neglected age groups (6–8 years and 10–15 years) and the understudied semantic-pragmatic domain.