Perception and production of emotional and linguistic prosody in children with cochlear implants

Prosody - rhythm, stress and intonation - is the melody of language. It has
many functions, but they can be divided into two types: linguistic and
emotional prosody. Linguistic prosody tells you something about the meaning of
a sentence, whereas emotional prosody tells you something about the speaker. If
you cannot hear prosody, you miss out on essential information such as what the
most important word (*focus*) and what the emotional content of the sentence
is. This is to some extent the fate of users of cochlear implants (CIs), who,
despite the device*s benefits for deaf people, have been shown to have great
difficulties in discriminating several aspects of prosody, most importantly
intonation because it is conveyed by pitch. Children with CIs have problems
hearing emotions and risk having a delayed linguistic and socio-emotional
development. This could in part be due to their lack of experience with
prosody. The link between the way the voice is being perceived by CI recipients
and the development of the communicative functions that are mediated by that
voice is still not understood. This research aims to fill in that gap.

Primary Objective: in what way, if any, do children with cochlear implants
process prosody differently from each other and from normally hearing children?

Secondary Objective(s):
1) is there a processing difference between linguistic and emotional prosody?
2) is there a processing difference between left and right implanted children?
3) is there a processing difference between temporal and pitch related cues?
4a) is there a processing accuracy difference between production and perception
of prosody?
4b) is there a correlation between production and perception accuracy of
prosody?
5) are there interactions in processing difference between any of the above
conditions?

The design of this study is that of a comparison of behavioral intervention in
two experimental groups and three control groups. All groups will perform the
same set of behavioral tests.

The two experimental groups are:
a) a group of children with early cochlear implantation (around 1 year of age)
and
b) a group of children with late cochlear implantation (around 4 years).
They all have equal time of experience (hearing age) with their implant.

The three control groups are groups of normally hearing children matched for
a) hearing age with all the patients
b) chronological age with the early implanted children
c) chronological age with the late implanted children

This design allows for testing if the total time of implant experience
(comparison with hearing-age matched controls) is the factor that determines
performance or if chronological age (i.e., general maturation) also plays a
role (comparison with chronological-age matched controls). If it does, the
study will reveal to what extent, if any, the patients* development is delayed
with respect to that of typically developing peers.

Participants are asked one hour and a half of their time (excluding time for
traveling) to take part in 9 tests assessing accuracy and latencies of
responses and including time for explanation and pauses. Travel expenses are
reimbursed. We test the perception and production of emotional and one type of
linguistic prosody in 4 tests. These 4 tests are preceded by 5 pretests for the
baselines of general object/color naming, non-linguistic emotional processing,
general intonation processing, general linguistic perceptive and productive
developmental level and nonword repetition. Subjects respond by pointing at
pictures on a screen (in some tests) and by giving a verbal reaction to a
question (in other tests). Although responses can be wrong or right, feedback
to the children will always be positive.

There are no risks in relation to participation in this study. The only
discomfort is in spending time; this amounts to two and a half hours at maximum
(including perhaps as much as an hour of pauses) altogether (excluding time for
traveling if necessary). Travel expenses are reimbursed. This time investment
is justified because it is the least that can be done to provide us with
valuable insights into the socio-emotional and linguistic development of
children with and without cochlear implants; with implants, because it shows us
some of their capabilities and limitations in the use of prosody, information
that could focus language and speech therapy onto what they have difficulty
with; without implants, because should they ever acquire socio-emotional or
communicational problems, we have learned that one of the possible factors
correlating with them (i.e., causing them or being caused by them) is the
processing (perception and/or production) of prosody.

This study can only be performed on children with CIs, because it is the only
way to test the role of the sensitive period in early natural language
acquisition (between 0 and 4 years). This is because CI children are the only
population experiencing delayed onset of verbal language acquisition. Secondly,
in order to know if CI children develop differently than normally hearing
children of the same age or the same amount of language experience, real
patients are needed. This could have implications for the way language and
speech therapy for CI children is designed.