The Method of the Main Tone Detection in the Structure of Electromyographic Signals for the Task of Broken Human Communicative Function Compensation

Abstract

In the work the method of electromyographic signals processing for the task of broken human communicative function compensation is developed. The method allows to detect the signs of main tone in the structure of electromyographic signals, that were recorded from the surface of patients neck near the vocal folds. Using this signs it is possible to identify the mentally spoken vowel and vocalised consonant phonemes and to identify the speech of patients with broken or lost communicative function. The developed method includes two stages, namely: preparatory and basic. The purpose of the preparatory stage is to obtain data on the individual features of the patient's speach, in particular the approximate value of the main tone frequency and the frequency interval of the main tone frequency when patient is trying to utter test sequences of sounds at certain points in time. These data are necessary to enable the use of the basic stage of the method, which involves the processing of electromyographic signals recorded in an arbitrary attempt to pronounce arbitrary sounds, words or phrases by the patient. It is proposed to processing the electromyographic signals by methods of spectral-correlation analysis using the sliding window method if presenting of such biosignals in the form of a piecewise stationary random process to detect the time intervals of the presence of main tone signs. Within each sliding window the estimates of the power spectral density distribution are calculated and averaged over the frequency and power within the predetermined interval of existence of the main tone frequency. The obtained averaged estimates make it possible to set the time intervals of the main tone presence and, accordingly, the subsequent identification of vowel and consonant vocalised phonemes. The experimentally registered EMG signal was processed by the developed method with different values of the sliding window width.