Variables influencing ITA-Matrix: language and cognitive functions in young adults implanted in childhood

Introduction: There is little research on how the ability to recognize speech in noise develops over time in young adults implanted in childhood. Executive functions (EFs) are a set of high order cognitive processes and are considered among variables affecting speech perception in noise (SIN). Aim: To increase knowledge of variables influencing development of speech perception in noise, especially for cognitive variables, to improve theoretical understanding and rehabilitation procedures. Material and methods: 62 subjects aged 18–27 years have been recruited. 50% implanted with AB, 40% with Cochlear and 10% with Med-El devices respectively, with a mean follow-up 22 years. All of them followed oral rehabilitation, none of them had associated disabilities. Audiological tests included SF-PTA, speech perception in quiet, SIN with fixed SNR and adaptive Matrix sentence test. Language competences included lexicon and morphosyntax, while EF included short term and working memory, verbal working memory (VWM), fluid intelligence and auditory attention. Results: Subjects showed nearly 100% for words and sentences in quiet and substantial deterioration for sentences in noise at SNR+10. ITA-Matrix values were significantly worse when compared to normative values, with a median SRT of –1.3 dB SNR for the whole sample. ITA-Matrix is strongly correlated to expressive vocabulary and morphosyntax, and with most executive function outcomes. The linear regression model VWM explained 21% of variance for ITA-Matrix, while in linear regression for audiological variables SF-PTA and sentences recognition in quiet explained 44% of variance. Conclusions: These data contribute to the definition of average SIN long-term outcomes expected in subjects implanted during childhood whilst increasing our knowledge of the effects of variables such as age at CI, language and EF. Innovation of the present study highlights how the development of SIN is influenced by language competences and cognition even adjusting for age at CI and age at implant.