Background: Rapid palatal expanders have a screw that covers the palate and may affect speech. Methods: RPEs were treatment planned for 22 patients. Speech recordings were completed at 6 different time points. Analysis for speech acceptability, /i/ vowel formants, and /s/ and /∫/ fricative spectra were analyzed. Results: When the appliance was inserted, speech acceptability deteriorated but improved over time. For vowel /i/, the first formant increased and second formant decreased. For fricatives (/s/, /∫/), low to high frequency ratios indicated that the sounds were distorted when the appliance was inserted. The formants and ratios returned to normal levels over time. Examination of the four spectral moments found the spectral mean decreased, standard deviation increased, skewness became more positive, and kurtosis decreased at appliance insertion. Repeated measures ANOVAs found significant effects for time for all acoustic measures. Conclusions: Speech was altered when the appliance was inserted, but improved over time.

Background: Rapid palatal expanders have a screw that covers the palate and may affect speech. Methods: RPEs were treatment planned for 22 patients. Speech recordings were completed at 6 different time points. Analysis for speech acceptability, /i/ vowel formants, and /s/ and /∫/ fricative spectra were analyzed. Results: When the appliance was inserted, speech acceptability deteriorated but improved over time. For vowel /i/, the first formant increased and second formant decreased. For fricatives (/s/, /∫/), low to high frequency ratios indicated that the sounds were distorted when the appliance was inserted. The formants and ratios returned to normal levels over time. Examination of the four spectral moments found the spectral mean decreased, standard deviation increased, skewness became more positive, and kurtosis decreased at appliance insertion. Repeated measures ANOVAs found significant effects for time for all acoustic measures. Conclusions: Speech was altered when the appliance was inserted, but improved over time.