Detection of Voice Activity Based on the Angle of the Slope of the Approximating Line of the Eigenvalues
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Abstract
The article discusses a method for detecting voice activity with the aim of improving the effectiveness of noise reduction methods in the conditions of low signal-to-noise ratio. The presence of acoustic disturbances limits the use of VAD (Voice Activity Detection) and degrades the performance. Special attention in the study is given to VAD methods that work in the interest of noise reduction systems, for estimating noise in noisy speech signals. The high efficiency of subspace-based noise reduction methods, based on the Karhunen–Loève transform, has prompted the search for a simple and reliable VAD for them. The method proposed in the article for voice activity detection does not require additional transformations of the noisy speech and facilitates the detection of voice activity in subspace-based noise reduction methods.
The proposed VAD utilizes the slope angle of the approximating line of the adjusted eigenvalues as the classification feature for speech frame classification during voice activity detection. The implementation of this approach involves an adjustable eigenvalue spectrum. By subtracting the noise variance from the eigenvalues of the input data covariance matrix, the reduction of noise energy in the observation is achieved. The use of the improved estimation of the noise variance takes into account the presence of additive noise components in the signal space. An adaptive threshold based on the input signal-to-noise ratio is proposed as the decision criterion in the study. A comparative analysis of the performance of the proposed VAD under the influence of color noise was conducted compared to the G.729 VAD codec. The implementation of the VAD models was done in MATLAB and evaluated using objective parameters for assessing erroneous decisions in noisy conditions. The presented simulation results indicate the effectiveness of the proposed method at low signal-to-noise ratios (down to 0 dB). The proposed method for voice activity detection increases speech detection accuracy and reduces the number of VAD erroneous decisions. The conducted research can be used to improve noise suppression systems.
