To provide a technique for automatically configuring a whitening filter with a frequency warping parameter optimized for increasing the resolution of a frequency band with a concentration of poles to a required level.
A system is so configured that a signal passed through an all-pass filter with a warping parameter λ is processed by a whitening filter and that an all-pass filter with a warping parameter -λ is then applied to restore a frequency axis, and thereby an optimum value of λ is determined to optimize the whitening filter. Firstly to that goal, an AR order p is automatically estimated with λ=0. A spectral distance dλ is calculated using a discrete Fourier transform spectrum value passed through the all-pass filter with the warping parameter λ and a discrete AR spectrum value passed through the all-pass filter with the warping parameter λ. A value of λ which minimizes the spectral distance dλ is set as the warping parameter, and the whitening filter is configured with the optimized warping parameter.
Tasaichi Tanae
Yoshihiro City
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