This study presents a case report of an 63-year-old man with profound sensory hearing impairment in both ears. The aim was to assess speech perception after 6 years of cochlear implant activation. The patient was diagnosed with otosclerosis and began using a hearing aid only in the left ear. He used hearing aids for 10 years and then underwent cochlear implant surgery. The procedures used in the assessment of speech perception were as follows: List Sentences and Balanced Words. Both are part of the of adult deaf assessment protocol of the Audiological Research Center, University of São Paulo Bauru campus. During the first 3 years of implant use, the patient scored more than 80% on tests of speech perception. From the fourth year onwards, there was a sharp decrease in levels of speech perception. The optimization of the maps in the cochlear implant and changes in program parameters, such as pulse width, reset of T- and C-levels, balancing of the electrodes, and setting of maxima, were adopted as alternatives for 2 years. Currently, the patient performs quarterly programs, and the balancing of the electrodes was shown to be the factor that was most related to changes in speech perception.