الفهرس 
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Abstract
Speech recognition is the ultimate goal of cochlear implantation. Speech perception in cochlear implants (CI) depends on the resolution of frequencies, exposure time and working memory. Frequency discrimination is especially difficult in cochlear implant which can be explained by poor pitch perception. The limited electrode number may limit accurate harmonic representation of the acoustic signal. Spectral resolution is also limited by the spread and interaction of currents between adjacent electrodes and the uneven neural survival along the length of the cochlea.
Working memory is of a special importance in the process of speech and language development and is expected to contribute to the vast variability in CI speech reception and expression outcome. Working memory is the temporary storage mechanism for signal awareness, sensory perception and information retrieval from long-term memory. Speech requires short-term working memory to encode, store, maintain and retrieve phonological and lexical representations of words for both speech perception and production.
The aims of this study were to evaluate behavioral speech discrimination in cochlear implantees using consonant emphasis materials and to evaluate working memory in those patients and assess its possible effect on their consonant discrimination abilities.
Fifty five CI patients were included in this study. Their aided thresholds were less than 40 dBHL. Consonant speech discrimination was assessed using Arabic consonant discrimination words. Working memory was assessed using Test of Memory and Learning-2 (TOMAL-2).
Subjects were divided according to the onset of hearing loss into prelinguals and postlinguals. Consonant classes studied were fricatives, stops, nasals and laterals. The performance of each group on the list of high frequency CVC words was 64.23% ± 17.41 for prelinguals and 61.70% ± 14.47 for postlinguals. These scores were significantly lower than scores on PBWLs of 79.94% ± 12.69 for prelinguals and 80.80% ± 11.36 for postlinguals. The lowest scores were for the fricatives. Working memory scores were strongly and positively correlated with speech discrimination scores for both lists.