Research on denoise algorithm of water flow sound in coal mining face
The water damage accident at the coal mining face is preceded by the sound of water flowing. To reduce the influence of noise interference of common mechanical equipment on the sound recognition of water flow, this paper proposes an improved wavelet threshold noise reduction method. To compensate the loss of high-frequency signals in the process of water flow sound acquisition, pre-emphasis, framing, and windowing are pre-emphasized. The compromise method of wavelet soft and hard threshold functions is employed to improve the threshold function, avoiding the additional oscillation problem caused by signal processing. The number of decomposition layers j is introduced into the fixed threshold, and the variable threshold maximizes the separation of the water flow acoustic signal from the noise signal. Our results show the hard threshold function improves the output signal-to-noise ratio by more than 1 dB and reduces the noise by about 15％ when compared with those of spectral subtraction, subspace method and wavelet threshold method. Compared with the soft threshold function of the wavelet threshold method, the output signal-to-noise ratio increases by over 1 dB when the input signal-to-noise ratio ≥0 dB. The improved wavelet threshold noise reduction method effectively reduces the noise interference of mechanical equipment in the water flow acoustic signal.
water flow soundnoise reductionwavelet transformthreshold functionsignal-to-noise ratio
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