Investigating language processing efficiency in preschoolers and school-aged children with hearing loss

Spoken language outcomes of children with hearing loss (HL), wearing hearing aids (HAs) and cochlear implants (CIs), have improved with early fitting and intervention. However, delays with language experience early in life and poor acoustic transmission by hearing devices may still pose challenges for real-time language processing. Early in development, slower processing may alter the development of linguistic representations. Later on at primary school-age, slower processing may cause children to miss out on important communicative interactions, and lead to increased listening effort and fatigue.

Early in development, perceiving small phonemic distinctions is necessary to differentiate word meanings, but hearing devices likely reduce this ability. This may lead preschoolers with HL to experience difficulties with real-time word recognition. Chapter 2 of this thesis assessed whether preschoolers with HL have access to lexical processing mechanisms in the same way as NH peers, by investigating real-time word recognition of words in high- and low phonological competition contexts. We found that words in the presence of a phonological competitor (e.g., /bin-pin/ and /map-mat/) altered the processing dynamics for children with HL vs. NH. This suggests that HL may increase difficulty with competitor suppression during word recognition. These results have implications for how efficiently preschoolers with HL can distinguish similar sounding words, refine word representations, and learn new words.

When children with HL reach school age, they have likely acquired functional language capacity, which raises the question of whether they can use this capacity to navigate in the real world. By assessing the language abilities of children with HL in ideal listening situations, we may overlook language processing challenges in everyday situations, where speech may be fast and environments may be noisy. Chapters 3 and 4 of this thesis investigated whether children with HL are slower than NH peers to process sentences spoken at a fast vs. normal speaking rate in quiet (Chapter 3) and in noise (Chapter 4), resembling what they may encounter in the classroom. We found that children with HL, compared to NH peers, experience delays in sentence processing in quiet and noise. Furthermore, in noise, the sentence processing of children with HL and NH was affected by fast speech. However, neither the noise nor the quiet study found evidence that children with HL were more affected by fast speech than NH peers. Together, these results have implications for how well children with HL can access communication in classrooms.