Unified Speech-Like Interference for Active Protection of Speech Information

Abstract

The paper considers the possibility of creating a speech-like interference for the means of vibro-acoustic protection of speech information based on tables of syllables and words of the Russian language. The choice of research directions and experimental conditions is substantiated: synthesis of sound files by random sampling of speech elements from a database, research of spectra of synthesized noise, algorithm for creating interference of the “speech choir” type, study of autocorrelation functions of synthesized speech-like interference, as well as their probability distribution density. It is shown that the spectral and statistical characteristics of the synthesized speech-like interference type "speech choir" of five voices are close to similar characteristics of real speech signals. At the same time, the speech choir was formed by averaging the instantaneous values of temporary realizations of sound files. It is shown that the spectral power density of the speech-like interference of the “speech choir” type practically is not changed with the number of averaged “voices” starting from five. The probability density distribution of the speech-like interference value with an increase in the number of voices in the “speech choir” approaches the normal law (unlike a real speech signal whose probability density is close to the Laplace distribution). Evaluation of the autocorrelation function gave a correlation interval of several milliseconds. The articulation tests of speech intelligibility using synthesized speech-like interference with different signal-to-noise ratios showed the possibility of reducing the integral noise level by 12-15 dB compared to noise-like interference. The dependencies of verbal intelligibility on the integral signal-to-noise ratio are constructed on the basis of polynomial and piecewise linear approximations. A preliminary assessment of a possible impact of speech-like interference on the psycho-emotional state of a person was performed. The direction of further research on increasing the efficiency of algorithms for generating speech-like interference is discussed.