Speech and Sign Perception
in Deaf Children with Cochlear Implants
Although a cochlear implant (CI) restores access to sound and speech for
profoundly deaf children, there is substantial inter-individual variation in
outcomes and many children with a CI continue to be delayed in their spoken
language development. This suggests that they may benefit from alternative
modes of communication such as sign language. However, the role of signed
input in the education of children with a CI is much debated.
The aim of the present thesis was two-folded: to explore underlying proces-
ses in speech perception that may help to explain inter-individual variation
in outcomes, and to obtain insight into the effects of signed input on spoken
language abilities. To that end, this thesis investigates speech and sign per-
ception in 5- to 6-year old children with a CI. More specifically, it examines
and interrelates the use of acoustic and visual cues in phonetic categorization
and the representation of phonetic contrasts in novel words and signs. Additi-
onally, it investigates the effects of bimodal (i.e., simultaneously spoken and
signed) input on speech perception.
The analyses show that children with a CI have fuzzy boundaries between
sound categories and have difficulties to represent phonetic detail in novel
words. Weakly-specified auditory phonological-lexical representations likely
negatively impact speech processing. Importantly, signing experience did not
negatively affect their speech perception and bimodal input seemed to even
facilitate spoken word recognition. Together, these findings form an argu-
ment for bilingualism in a spoken and a signed language as the ultimate
goal in the rehabilitation and education of children with a CI.