Early diagnosis of congenital defect of hearing poses new challenges for a multidisciplinary team of pedoaudiologists, ENT (ear-nose-throat) specialists and speech therapists. This study assessed the perception of phonemes in children with a cochlear implant and the possibilities of applying acoustical solutions in the audiologic evaluation. The participants were 17 implanted children, aged 5-9 years, who received a cochlear implant when they were from 18 months to 3 years old. Detection thresholds and discrimination score were assessed. This study also aimed at verifying the possibilities of applying the digital audioprocessing algorithm in clinical practice. The test based on the phonemes aa, uu, ii, ss, sh (Ling 5 sound test) was used. The test was modified in the frequency domain - the main aim of this modification was to improve the precision of the reconstruction of the audible threshold. The results indicated significant correlations between pure tone audiometry results and thresholds of phoneme detection [dB SPL]. The identification score in this group was 95-100% for sound pressure level 65 dB SPL.