Evaluation of low-set tongue position using zero-crossing rates and mel-frequency cepstrum coefficients

Tongue-thrust swallowing habit from a low-set tongue position causes open bite when the tongue pushes the upper and lower front teeth. This study aimed to examine tongue position discrimination by speech zero-crossing rates and Mel-frequency cepstrum coefficients (MFCCs). Participants (N = 225) underwent lateral cephalography to measure TPD (tongue-palate-distance) (TPD5). In addition, a trans palatal arch (TPA) was also attached to the oral cavity in nine adult participants (Non group), and a low-set tongue was imitated. Participants’ voices were recorded before and after wearing TPA, and analysis of zero-crossing rates and MFCCs was performed. TPD was measured to be 2.5(0∼16.5) mm from the central tongue, and a significant difference was found in zerocrossing rates and MFCCs between groups. As a result, we found that acoustic changes occurred due to the low-set tongue position. It was suggested that low-set tongue could be identified by speech.