OBJECTIVE: To investigate the prevalence of changes in tone, posture at rest, and in the general aspect of the tongue in the formation of speech. The investigation was based on records obtained during language assessments among children with phonological disorders. METHODS: This is a quantitative, descriptive analysis of secondary data collected from the VALDEF database (FAPERGS - Case number 0904179 and CNPq - process number 483886/2010-6). Notably, identifying a phonological disorder is a diagnosis of exclusion. Those who are unable to form the sounds required for Brazilian Portuguese may also present with structural abnormalities that affect the ability to form sounds. RESULTS AND CONCLUSIONS: The data show that 100% of the study population is considered normal. With regard to the ability to perceive tone, 97.92% were considered as normal and 2.08% presented with hypotonic tongues. The data revealed significant changes in tongue posture at rest: 40.86% were classified as normal, with tongue papillae; 27.95% had tongues that were lowered on the floor of the mouth; 26.88% had the tongue interposed between the teeth; and 4.30% had the tongue against the anterior incisors. The results showed changes in the posture of the tongue at rest, showing that the relationship between phonological and structural aspects must be verified in clinical assessment. These data will also allow us to quantify how such structural abnormalities can negatively affect speech intelligibility.