Ann E. Geers, Ph.D.
Center for Applied Research on Childhood Deafness
Central Institute for the Deaf, St. Louis, MO
The advent of cochlear implants has had a dramatic effect on the achievements of young profoundly deaf children. Spoken language competence is now available to many children who previously depended primarily on sign language for communication. Deaf children who receive an implant early in life, followed by a period of appropriate rehabilitation, achieve speech intelligibility and conversational fluency that exceeds levels observed in profoundly deaf children with hearing aids.
In 1996 the Center for Childhood Deafness at Central Institute for the Deaf began a study, funded by the U.S. National Institutes of Health, entitled: Cochlear Implants & Education of the Deaf Child. This study is designed document the effects of various education and rehabilitation models on the deaf child's ability to understand, produce and read English while using a cochlear implant.
All children included in the study were 8 or 9 years old, deaf before 3 years of age, were implanted under age 5 and had used an implant for 4 to 6 years. Children who met these criteria and also exhibited normal intelligence and came from an English home environment were recruited through cooperating implant centers across the US and Canada.
Testing of children occurred at cochlear implant research camps held in St. Louis each summer for the past 5 years. Approximately 15 children and a parent, attended each summer camp. All expenses were paid, including transportation, hotel accommodations for 4 nights and daily entertainment activities. Testing took place 2 hours each day for 3 days. Children were tested individually in their hotel rooms, which were converted to testing suites each morning. The parents attended educational seminars during this time and completed questionnaires and signed release forms for questionnaires sent to implant centers and therapists. In the afternoon, families participated in fun activities in and around the city of St. Louis.
A total of 180 families from 33 States and 5 Canadian provinces attended a research camp over the past 5 years. These children do not represent any single program or method, but rather come from the vast variety of educational settings represented across the United States and Canada. Data analysis for this study is still in progress and final results are not yet available. So far results have been analyzed for 136 children who ?were tested between 1997 and 1999.
Child and Family Characteristics
One-hundred two of the 136 children were known or presumed to be deaf from birth, 12 were deafened before 1 year of age, 15 between 1 and 2 and 7 became deaf at the age of 2. Most (57) were implanted at 3 years of age. An additional 43 were implanted at age 2 and 36 at age 4. All but nine of the children obtained a Performance IQ on the Wechsler Intelligence Scale for Children within or above the average range for their age. Most of the children were being raised in 2-parent families with 2 children. Only 11 of the 136 children were from single parent families. This group of parents were among the first to seek out a cochlear implant for their child, so they represent a highly educated group, with over half having at least one college graduate as a parent. The median family income was between $50,000 and $80,000, with 35 families making more than $80,000 per year.
Implant Characteristics
All 136 children had used the same electrode array, the Nucleus 22 from Cochlear Corp., for four to six years. Almost half of the children tested were at 5 years of implant use. Many of these children were first fitted with the MSP processor and later received the newer SPEAK processor. All but 20 of the children had switched to the SPEAK strategy by the time of the study. Fifty of them had used SPEAK for 4 or more years. Almost half had a fully active array with 20+ electrodes in their map. Only 12 of the 136 children had fewer than 16 active electrodes. The majority of children exhibited a wide dynamic range of over 1000 clinical units when summed across the electrode array. This indicates that a wide range of loudness levels in speech was available to these children from their processor.
Educational Factors
On average, these children received between 1 and 2 hours per week of therapy each year post implant, continuing into the year just completed before they attended camp. Therapist experience ranged from the lowest 5% who had no prior experience with either deaf children or cochlear implants to the top 50% of therapists with experience teaching more than 10 deaf children, including those with implants. On average, parents reported that they worked with their child daily for the first 2 years post implant, and between daily and weekly for the third year post and the year just completed. The percentage of children enrolled in full time special education classes decreased from about 60% before implant to about 20% at the time of the study. By the time of the study, over half of the children were fully mainstreamed.
Methodology was assessed with a rating that was designed to reflect the amount of emphasis on speech and auditory skill development. In mostly sign programs sign-only was often used for communication during some of each day. In speech and sign programs speech almost always occurred simultaneously with each signed word and sign-only or speech-only were rarely used. In speech emphasis total communication programs, speech-only was used for communication during some of each day. In cued speech programs a system of manual cues was used to complement lipreading but no sign was used. In auditory-oral programs the child was encouraged throughout the day to both lipread and listen to the talker with no signs provided.. In auditory-verbal programs the child was taught to rely on listening alone to understand speech.
A rank between 1 and 6 was assigned to each instructional mode for each year. . The mode score was averaged over 5 rating periods between pre-implant and the year just completed. Since a number of the children changed placement over time, this average score reflects the cumulative emphasis on speech and auditory skill development. Children with MODE scores of 4 or higher had spent most of their years in an oral setting, while those with mode average scores below 4 had been mostly in total communication settings.
Results
The outcome variables included in this study consist of batteries of tests designed to measure speech perception, speech production, language and reading. The analysis examines the effects of three independent variables: method, class placement and therapy on the outcome variables of speech perception, speech production, language and reading, correcting for any influence of characteristics of the child, the family and the implant. The conclusions that are supported by the data so far are as follows:
Children who obtained the greatest auditory benefit from their implant had higher communication mode scores (indicating more emphasis on speech and audition than on sign), a fully active electrode array, greater learning ability (I Q), a well-mapped implant device, earlier age at implantation and later onset of deafness.
Intelligible speech was associated with a well-functioning implant and families whose smaller size and higher income permited them to focus their efforts on supporting the childĄs development. With implant and family characteristics held constant, the most important factor associated with developing intelligible speech was enrollment in an oral educational program that emphasized speech over sign language. Therapy and parent intervention were also important, particularly during the first year post implant. Children who achieved the most intelligible speech were more likely to be placed in mainstream classes by the third year post implant. However mainstream placement throughout the childĄs post-implant educational experience is most conducive to speech development when the childĄs therapist had extensive experience teaching deaf children and working with children who had cochlear implants.
Children with the highest spoken language scores were those with fully active electrode arrays who were enrolled in oral communication programs.
Children with the highest reading scores were older (9 as opposed to 8 years old), had later onset of deafness, higher IQs, oral education, a fully functioning electrode array and mainstream placement, especially in the more recent years.
In summary, the child characteristics associated with better performance on the outcome measures were onset of deafness after birth, early implantation and good learning ability. The important implant characteristics included a full electrode insertion and a well-fitted map that allowed a full range of perceived loudness as stimulus intensity increased. When these factors were controlled for, the primary rehabilitative factor associated with performance outcome was educational emphasis on oral-aural communication. In addition, children who were most successful with their implant were placed in mainstream classes with relatively little sign language use by the time they reached 8 or 9 years old.