cochlear implants international, Vol. 11 Supplement 1, June, 2010, 336–39
Speech Perception Improvement in Children with Cochlear Implant Nassim Manouchehri and Mansoureh Adel-Ghahraman Department of Audiology, Faculty of Rehabilitation, Tehran University of Medical Sciences, Iran
Farzad Mobedshahi and Masoud Motesadi-Zarandi Cochlear Implant Center, Otolaryngology Research Center, Amir A’lam Hospital, Tehran University of Medical Sciences, Iran
Introduction Previous studies suggest that cochlear implant (CI) alone cannot probably provide all needs of many implanted subjects and more aural rehabilitation is necessary to maximize the benefits of device. Recent studies show that targeted auditory training significantly increases speech perception in CI recipients. The longitudinal studies have demonstrated that the greatest gains in performance occur in the first 3 months of use. The aim of this study was to assess improvement of speech perception in children with cochlear implants.
Method and materials Fourteen children (9 male and 5 female) with mean age 5.5P1.67 years implanted in Amir A’lam hospital from August 2004 to October 2006 were studied. Auditory training sessions was performed in 10 to 43 50-minute (mean 23P8.78) sessions. Sound awareness, speech discrimination, and comprehension were evaluated every 3 months for all recipients on 3 occasions. The third evaluation has been done only for 4 children. At the end of every 3 months, the children were assessed using an evaluation form,. This form consisted of 25 questions relating to 5 subcategories. The subcategories included the following: 1) sound awareness, 2) environmental sound discrimination, 3) speech sound discrimination, 4) auditory memory in close- and open-set 2, 3, and 4 words, and 5) comprehension containing retelling short stories with and without picture, answering to complicated questions, and close- and openset speech perception in noise. Answers were scored as no response=0, weak=1, unstable=2, almost complete=3, and complete=4. Total scores were calculated and compared with previous evaluations. © 2010 W. S. Maney & Son, Ltd
DOI 10.1179/146701010X12671177989714
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Results On average every child underwent auditory training for 6.64 months (with minimum 3 and maximum 12 months). All children obtained a complete score for sound awareness in the first evaluation. For environmental sound discrimination, 71.3 per cent, 84.36 per cent, and 100 per cent of children completely answered the questions for three evaluations. For speech sound discrimination, 34.7 per cent in the first, 57.04 per cent in the second, and 85 per cent in the third evaluation obtained complete scores (Table 1), and for auditory memory, 21 per cent in the first, 57.12 per cent in the second, and 83 per cent in the third evaluation got complete scores (Figure 1). For the skill of story rephrase and comprehension, no child could answer the questions in the first evaluation session; however, 12.83 per cent and 12.83 per cent of children obtained complete scores for the second and third evaluations, respectively. The scores obtained for 5 categories are fully explained in Figure 2. The mean total score of the first evaluation was 43.21 per cent, of the second was 63.76 per cent, and of the third evaluation was 78 per cent (Figure 3). Finally, children’s performance continued to develop, as there was statistically significant difference between the scores of the first and of the second evaluation (P=0.002). No significant difference was found between the second and the third evaluation (P=0.53).
Discussion The previous studies suggest that significant auditory plasticity is observed in CI users. As speech patterns spectrally decrease in cochlear implantation, passive learning via long-term use of the implant may not completely provide learning capability for new stimulation patterns. Contrary to passive learning, active auditory training has presumably required existing CI users’ auditory plasticity and learning of stimulated speech patterns are electrically facilitated. Busby et al. (1991) explained that only little changes occur in speech performance after 10 1-h auditory training sessions in CI patients. Dawson and Clark (1997) noted more results for 50-minute 10 vowel perception training sessions in implanted subjects. Four out of the 5 patients revealed considerable improvement in vowel perception and recoveries were remained 3 weeks TABLE 1 PERCENT OF CHILDREN OBTAINED COMPLETE SCORE FOR SPEECH SOUND DISCRIMINATION IN 3 EVALUATIONS Question
1st
2nd
3rd
Stabilized words discrimination
57.1
91.7
100
Parental and familial sound discrimination
42.9
61.3
100
Tone sound discrimination
64.3
100
100
Similar words discrimination
28.6
69.2
100
Speech/non-speech sound discrimination
28.6
46.2
75
7.1
7.1
50
Singing/light music discrimination Male/female sound discrimination
14.3
23.1
75
Similar phrase and sentences detection
42.9
76.9
100
338
N MANOUCHEHRI et al.
figure 1 Percentage of children who obtained complete scores in auditory memory tasks in 3 evaluations. C-2Ws=close-set 2 words memory, O-2Ws=open-set 2 words memory, C-3Ws=close-set 3 words memory, O-3Ws=open-set 3 words memory, C-4Ws =close-set 4 words memory, O-4Ws=openset 4 words memory.
figure 3
figure 2 Percentage of children who obtained complete scores for 5 categories in three evaluation sessions.
Averages of total scores in 3 evaluations.
after auditory training was finished. In our study, CI users are not able to fully achieve skills of discrimination, recognition, and comprehension after 3 months auditory training and after second evaluation (the second 3 months) significant improvement obtained for discrimination and recognition skills; however, accessing full comprehension skills needs more time. Therefore, it is important to notice the most efficient and effective time course for training. How long or how must auditory training be done to considerably improve function? It is possible to consider previous electrophysiological studies. Wright and Sabin (2007) found that frequency discrimination needed more training than temporal interval discrimination; therefore, proposing that some perceptual actions may need longer periods of training. Nogaki et al. (2007) noted that, for normal hearing subjects in tasks like listening to severely distorted
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acoustical stimuli via implant, the total amount of auditory training may be more significant than its frequency.
Conclusion It seems that sound awareness ability is achieved rapidly. For access to other abilities for speech and environmental sound discrimination, more extensive training is needed. Speech comprehension as the last, and most important ability is not accessible for communication within this rehabilitation period; therefore, the parents should be warned to expect to continue the rehabilitation process.
Acknowledgement This study was supported by Cochlear Implant Center, Otolaryngology Research Center, Amir A’lam Hospital, Tehran University of Medical Sciences, Iran.
Bibliography Busby, P.A., Roberts, S.A., Tong, Y.C. & Clark, G.M. 1991 Oct. Results of Speech Perception and Speech Production Training for Three Prelingually Deaf Patients Using a Multiple-Electrode Cochlear Implant. Br J Audiol, 25(5): 291–302. Dawson, P.W. & Clark, G.M. 1997 Dec. Changes in Synthetic and Natural Vowel Perception After Specific Training for Congenitally Deafened Patients Using a Multichannel Cochlear Implant. Ear Hear, 18(6): 488–501. Nogaki, G., Fu, Q.J. & Galvin, J.J. 3rd. 2007 Apr. Effect of Training Rate on Recognition Of Spectrally Shifted Speech. Ear Hear, 28(2): 132–40. Wright, B.A. & Sabin, A.T. 2007 Jul. Perceptual Learning: How Much Daily Training is Enough? Exp Brain Res, 180(4): 727–36. Epub 27 February 2007.
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