PURPOSE: to evaluate how long after activation one can achieve the desired auditory thresholds in individuals multichannel cochlear implant users from different age groups. METHOD: a retrospective cross-sectional from a database, approved by CEP / FMUSP, under number 779/06. Individuals implanted between January 2005 and September 2008, whose files had preoperative audiometric data and 3, 6 and 12 months after CI were included. Seventy-two patients fulfilled the criteria, and they were divided in two groups according to age: group I (17 year old) and GII (18-66 year old). Analysis of variance (ANOVA) of one factor in order to verify the interaction between the mean threshold and time after CI were used. RESULTS: we observed that 15 of the GI have reached around 30dBNA thresholds at 3 months after implant. The same happened to 26 patients of GII. We found significant interaction between time (F (3.140) = 91.973, p = 0.00) and the average hearing thresholds. Post-hoc analysis in the GI group were statistically significant differences for comparisons between HA and 3 months after implantation (p = 0.00) and between 3 and 12 months (p = 0.28). For GII only for comparison between HA and 3 months (p = 0.00). CONCLUSION: a significant hearing change may be observed beginning from three months after IC, but this result is not found in all implanted subjects.