In the study for the first time on the material of the Russian language, acoustic (spectral and temporal) characteristics of stressed vowels from word cut from spontaneous speech of children aged 14-16 years, recognized by auditors with different probability, aredescribed on the basis of the Russian language. Perceptual analysis of children’s speech was conducted, aimed at recognizing the meaning of adolescent’s words by adults. For words recognized with different probabilities (0.75-1.0 and 0-0.25), the values of the duration of the stressed vowels, the duration of their stationary sections, the pitch frequency value (F0) are described, the values of the formant frequencies (F1, F2). Formant triangles of coordinated vowels for the Russian language (a, y, u) are constructed and their areas are defined.