The given research is aimed at registering and analysing speech signal obtained through a microphone placed in the proximity of the vocal folds and comparing it with the output speech signal. The external microphone was located near the lips of the subject. The internal one was located in the proximity of the subjects’s vocal folds by a phoniatrician with the use of special medical equipment. The speech signal containing isolated vowels and connected speech was registered synchronously through both microphones. The main interest of the paper is the acoustic characteristics of these signals, mainly, the vowel formant structure. Besides, the non-linearity of the vocal tract system was considered. The new method of obtaining frequency characteristics of the articulation system is used. The coprocessing of several acoustic realizations helps to elaborate the methods of discrimination and modeling the transfer functions of the voice source and filter components of the vocal tract. The speech signals that are influ