$t$	real time in raw signal
$\mathsf{\tau }$	time delay of signal
$W_{j,k}^n\left(t\right)$	wavelet packet kernel function
$j$	wavelet packet index scale
$k$	wavelet packet translation operation
$n$	wavelet packet modulation parameter
$\varphi$	wavelet packet first mother function
$\psi$	wavelet packet second mother function
$h\left(k\right)$	wavelet packet quadrature mirror filter
$g\left(k\right)$	wavelet packet quadrature mirror filter
${\omega }_{j,n,k}\left(t\right)$	wavelet packet coefficient
$P_s^{\prime }\left(w\right)$	signal spectrum denoised by spectral subtraction
$P_s\left(w\right)$	raw signal spectrum
$P_n\left(w\right)$	noise signal spectrum
$\widehat{X}\left(b,a\right)$	wavelet spectrum denoised by spectral subtraction
$Y_s\left(b,a\right)$	wavelet spectrum of raw signal
$N_n\left(b,a\right)$	wavelet spectrum of noise signal
$\alpha$	reduction factor of wavelet spectral subtraction
$a$	wavelet filter location parameter
$b$	wavelet filter scale parameter
$x_1$	number of divisions in time domain
$x_2$	threshold value for parameter to be outstanding
$x_3$	minimum number of outstanding parameters for window to be outstanding
$A$	number of outstanding windows
$A_{norm}$	normalized number of outstanding windows
$D_f$	number of divisions in frequency domain
$C_p$	penalty weight for N-R subtraction
$R_c$	outstanding degree of window
$L_S$	length of synchronized datasets
$N_n$	number of normal datasets
$N_a$	number of abnormal datasets
$N_{n-r,ij}$	number of normal datasets that make window at i-th row and j-th col outstanding in N-R spectrogram
$N_{a-r,ij}$	number of normal datasets that make window at i-th row and j-th col outstanding in A-R spectrogram
$B_{ij}$	counting number of i-th row and j-th col