A study on development of deaf children fitted with a Cochlear Implant

Oct 15 2009

A multidisciplinary group at Malaga University, headed by Ignacio Moreno-Torres, is collecting information on the milestones that mark the development of deaf children fitted with a Cochlear Implant (CI) and studying to what extent the social and family environment affects this development. This research is funded with 101,000 euro by the Andalusian Regional Ministry of Innovation.

The researchers have observed in this first year of the study that, three months after receiving the implant all the children showed improvement in their perception and ability to detect sounds around them. Children quickly learn that the CI is a device that allows them to hear and if it is deactivated they protest or make gestures asking that it be switched back on.

The first effect of the CI is an increase in the intensity of the sounds made by the children, which gives way to the production of sounds close to vowels. "Later, at between four and six months, sounds similar to syllables appear, such as bababa, mamama, etc. One of the children appeared not to following this sequence of development, as this child already produced abundant syllables before receiving the CI. This could be related to the type of stimulation received (Cued Speech, a system that makes it possible to perceive cued speech by sight through the simultaneous use of lip reading and a limited series of manual cues) although we will have to wait a few months before verifying if this initial progress is long-lasting and if the cause of the phenomenon is Cued Speech," explains Moreno-Torres.

Although there are differences between children, in general the first words usually appear six months following activation. "The only child on whom the study has been completed produced 50 different words in the final session," explained the professor. This datum is encouraging as it indicates that in only twelve months of the auditory experience it is possible to achieve what hearing children usually achieve in 18 months, which means that the initial difference compared to hearing children is being reduced.

Linguistic and cognitive development

Today there are means that enable the deaf to acquire verbal language, among which the Cochlear Implant is key. The Cochlear Implant, which has been in use since 1957, carries out the function of the human ear, transforming acoustic signals into electrical signals that stimulate the auditory nerve. Despite the marked achievements, the implant does not always guarantee linguistic progress equivalent to that observed in hearing people. For this reason, since 2007 this research group at Malaga University have been studying the linguistic and cognitive development of a group of children who received the implant before they were two years old.

Up to now, eleven children (of the planned total of twelve) have taken part or are in the process of being included in the project. Of these, seven received the implant at San Cecilio University Clinical Hospital (Granada) and four at Las Palmas University Hospital. A total of nine data collections are made with respect to each child; the first prior to implantation and the others beginning a month and a half following the date of activation.

In the future and maintaining the same initial hypothesis (critical role of the social and family environment), another study will be carried out that will provide valuable data on the subsequent development stages. Specifically, the aim to study linguistic progress in medium term (phonology, lexis and grammar) after three or four years of use of the Cochlear Implant. Furthermore, they hope to be able to assess to what extent these children are ready to access primary schools in equal conditions to hearing children.

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