PURPOSE: To determine whether the severity index that measures the percentage of consonants correct distinguishes children with speech sound disorders (SSD) according to measures of stimulability and speech inconsistency, as well as to the presence of heritability (familial history) and history of early recurrent otitis media. METHODS: Participants were 15 subjects aged between 5 and 7 years and 11 months, diagnosed as phonologically disordered. The PCC-R index was calculated for both words imitation and picture naming tasks, separately. The need to apply stimulability test was considered according to the criteria proposed in previous research for Brazilian Portuguese-speaking children. Speech inconsistency allowed the classification of subjects as either consistent or inconsistent. Data were statistically analyzed. RESULTS: Comparison between PCC-R calculated for picture naming and words imitation tasks demonstrated difference only for the need for the application of the stimulability test. Such difference was not observed in the speech inconsistency test. No difference was found at PCC-R values considering both familial and otitis media histories. CONCLUSION: The present research indicates that children who were submitted to the stimulability test presented lower values of PCC-R. However, PCC-R values were not determinant for differences among children, regarding the speech inconsistency test and familial and otitis media histories.