DOI: 10.22184/1993-7296.FRos.2026.20.2.122.136

Threats to the speech information privacy are often associated with interception (eavesdropping) through the technical channels, including any fiber-­optic communications. The functioning efficiency of the acoustic fiber-­optic channel for speech information leakage, i. e. the interception range, speech intelligibility and other parameters, is largely determined by the noise level of the informative optical signal during formation and propagation in the fiber-­optic channel. The noise interference is related to the penetration of external optical radiation into the leakage channel that can be ignored due to the light-­impermeable protective cable jackets. The noise level are primarily determined by the optical signal distortions in the fiber, exposed to the low-frequency random background physical fields in the environment, and its subsequent decorrelation. The average signal distortion is estimated by the decorrelation coefficient, and the integral noise estimation is based on the leakage channel noise ratio. The proposed method allows for the assessment of specifications of an acoustic fiber-­optic channel for speech information leakage based on its physical parameters.