[Improvement of speech perception in children with cochlear implant]

Although the ability of speech perception has been improved in implanted subjects with recent progress in technology, cochlear implantation alone is not enough and more aural rehabilitation is necessary. The aim of this study was to assess improvement of speech perception in children with cochlear implant. Fourteen cochlear implanted children with a mean age of 5.5 years participated in this study. Auditory training was performed in 10 to 43 sessions. Speech recognition and perception were evaluated every 3 months. Third evaluation was done only for 4 patients. Mean total score of the first evaluation was 43.21%, of the second was 63.76%, and of the third evaluation was 78%. All children obtained complete score for sound awareness at the first evaluation. In environmental sounds discrimination, 71.3%, 84.36%, and 100% answered completely to the questions of three evaluations respectively. In speech sounds discrimination, 34.7% in the first, 57.04% in the second, and 85% in the third evaluation obtained the complete score, and in auditory memory, complete responses were 21% for the first, 57.12% for the second, and 83% for third evaluation. In story rephrasing and comprehension, no one answered to questions completely. However, 12.83% obtained the complete score in the second and third evaluations. There were statistically significant differences between the first and the second evaluation [p=0.002]. Sound awareness ability seems to be achieved rapidly. Development of speech and environmental sound discrimination abilities, particularly speech comprehension which is the most important skill, need more impressive training

[Comparison of cognitive potential P300 with high and low frequency stimulus in early onset blind subjects]

Previous studies suggest that auditory stimulus frequency in normal subjects contribute to both P300 amplitude and latency measures. As occipital cortex devotes to other modalities including auditory inputs, the purpose of this study was to determine the effects of stimulus frequency in early blind subjects. Fifteen early blind subjects [8 males and 7 females] with mean age of 25.13 +/- 4.27 years were tested. Cognitive potential P300 was recorded in response to high [1000/2000Hz] and low [250/500 Hz] frequencies auditory stimuli using an oddball task in 70 dB nHL. While participants answered to target stimulus, amplitude and latency of P300 was recorded. With high frequency stimuli, mean amplitude in early onset blind subjects obtained 14.13 +/- 5.53 micro v and was 17.59 +/- 8.17 micro v with low frequency. With high and low frequency, mean latency of P300 obtained 295.60 +/- 31.33 ms and 317.38 +/- 21.71 ms respectively. Comparison of results between two stimuli showed that there were statistically significant differences between amplitudes [p=0.008] and latencies [p=0.001] of cognitive potential P300. Changing low frequency to high frequency results in decreasing both amplitude and latency. It seems that auditory stimuli frequency affect the P300 parameters in blind subjects