Patent ID: 6564184
Filing Date: 2003-05-13
Classification: G10L,H03H

Abstract:
A digital filter design method for noise suppression by spectral subtraction, including the steps of:determining a high frequency-resolution noisy speech power spectral density estimate from a noisy speech signal block; forming a piece-wise constant noisy speech power spectral density estimate by averaging power densities within frequency bin segments of said noisy speech high frequency-resolution power spectral density estimate; determining a high frequency-resolution background noise power spectral density estimate from a background noise signal block; forming a piece-wise constant background noise power spectral density estimate by averaging power densities within frequency bin segments of said high frequency-resolution background noise power spectral density estimate; determining a piece-wise constant digital filter transfer function using spectral subtraction based on said piece-wise constant noisy speech power spectral density estimate and said piece-wise constant background noise power spectral density estimate; wherein said step of forming a piece-wise constant noisy speech power spectral density estimate includes adapting the length of individual segments to the shape of said high frequency-resolution noisy speech power spectral density estimate; and wherein said step of forming a piece-wise constant background noise power spectral density estimate includes using the same segments for both said high frequency-resolution noisy speech power spectral density estimate and said high frequency-resolution background noise power spectral density estimate.