Identifiability and intelligibility of the speech of children with a cochlear implant: a comparison with normally hearing children and children with an acoustic hearing aid

Date: 8 July 2020

Venue: Online defence - Blackboard Collaborate - - -

Time: 3:00 PM

PhD candidate: Nathalie Boonen

Principal investigator: Steven Gillis & Hanne Kloots

Short description: PhD defence by Nathalie Boonen - Faculty of Arts


This dissertation investigated the speech and language of hearing-impaired primary school aged children. They were born with a hearing impairment and their hearing was aided very early on in life. Two issues pertinent to their long-term speech outcomes were studied. The first one related to the speech intelligibility of these hearing-impaired children: is their speech as intelligible as that of their normally hearing peers? The second one related to the children’s speech identifiability and addressed the question whether the speech of hearing-impaired (HI) children is distinguishable from the speech of normally hearing (NH) peers? For both topics, the speech of hearing-impaired children with cochlear implants (CI) and acoustic hearing aids (HA) was compared to that of NH peers.

The studies on speech intelligibility resulted in two important findings. On the one hand, it was found that the speech intelligibility of seven-year-old children with CI had not yet reached NH children’s level. As a group, their intelligibility scores were significantly lower than those of NH peers. On the other hand, intelligibility scores exhibited substantial individual variation: some children with CI scored well within the range of children with NH, while others clearly lagged behind.

In the studies on speech identifiability, it was found that listeners reliably differentiated the speech of NH and HI children, indicating that their speech was indeed identifiable. This result indicated that HI children’s speech contains marking cues that are salient to listeners. Future research has to investigate which cues are most salient to listeners. In the group of HI children, the results showed an effect of the length of device use for children with HA as well as for children with CI. Interestingly, this effect was far more pronounced in the latter group. Moreover, the results indicated that experience with the speech of (HI) children or familiarity with the native language of the child did not affect the judgements considerably.