This article describes a method of diagnosis of speech disorders, the results of their own research, as well as a method of modernization of the prosthesis of the obturator to correct speech disorders. The study was conducted with the help of the developed tables that contain the two-letter syllables. Diagnostic sounds at the beginning of the syllable contains an open vowel. Special attention is paid explosive consonants as characteristic sounds in the diagnosis of speech disorders in patients with acquired defects of the upper jaw of the second group C.Y. Courland. To identify the quality of speech used quantitative parameters, among which: • frequency characteristics of each sound; • the ratio of the rise time of the envelope sound intensity to the total duration of the sound; • the ratio of the duration bows explosive consonants to the duration of the pronunciation of the sound (for smycnyx consonants); • the ratio of the amplitude of the sound intensity of the explosion to the amplitude of the noise components during the bows. The evolution of the recovery process speech formulated in four audio recordings made at different stages of complex rehabilitation ofpatients. Write vowels were used to identify speech rate and save formant frequencies in different periods of life of the patient. Frequency analysis was performed to control the absence of the influence of the established prostheses sounds that should not be changed in this scheme ofprosthetics. As a result of inadequate prosthesis in the process of speech occurs the flow of air from the oral cavity into the nasal cavity. This effect causes the presence of the nasal formant in the acoustic component of the voice. Pronunciation of smycnyx consonants are analyzed in part two-letter syllables, where SMACNA followed by a vowel. The end of the vowel sound means the beginning of bows, formed the increased pressure in the oral cavity and subsequent explosion in the opening of the lips. Expert evaluation revealed no significant differences in the sound of the syllables containing Nesmachnyi consonants pre-and final phases of complex rehabilitation. Selective instrumental analysis coincides with an expert assessment: differences in the spectral characteristics of the sounds are practically absent. For the full differentiation of the oral cavity from the nasal cavity of the proposed use adhesive paste-like consistency of the material. The result of the execution of measures for sealing the mouth shows a significant improvement in speech quality. The result is confirmed by the expert and instrumental evaluation of audio recordings.