Digital filter design method and apparatus
First Claim
1. 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.
1 Assignment
0 Petitions
Accused Products
Abstract
A digital filter design apparatus for noise suppression by spectral subtraction includes a first spectrum estimator for determining a high frequency resolution noisy speech power spectral density estimate from a noisy speech signal block. A second spectrum estimator determines a high frequency resolution background noise power spectral density estimate from a background noise signal block. Averaging units form a piece-wise constant noisy speech power spectral density estimate and a piece-wise constant background noise power spectral density estimate. These averaging units are controlled by devices for adapting the length of individual segments to the shape of the high frequency-resolution noisy speech power spectral density estimate and for using the same segmentation in both piecewise constant estimates. A piece-wise constant digital filter transfer function is determined using spectral subtraction-based on the piece-wise constant noisy speech power spectral density estimate and the piece-wise constant background noise power spectral density estimate.
26 Citations
20 Claims
-
1. 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. - View Dependent Claims (2, 3, 4)
-
-
5. A digital filter design method for non-linear echo cancellation, including the steps of:
-
determining a high frequency-resolution speech power spectral density estimate from a residual echo containing speech signal block;
forming a piece-wise constant speech power spectral density estimate by averaging power densities within frequency bin segments of said speech high frequency-resolution power spectral density estimate;
determining a high frequency-resolution residual echo power spectral density estimate from an echo signal block;
forming a piece-wise constant residual echo power spectral density estimate by averaging power densities within frequency bin segments of said high frequency-resolution residual echo power spectral density estimate;
determining a piece-wise constant digital filter transfer function using said piece-wise constant speech power spectral density estimate and said piece-wise constant residual echo power spectral density estimate;
wherein said step of forming a piece-wise constant speech power spectral density estimate includes adapting the length of individual segments to the shape of said high frequency-resolution speech power spectral density estimate; and
wherein said step of forming a piece-wise constant residual echo power spectral density estimate includes using the same segments for both said high frequency-resolution speech power spectral density estimate and said high frequency-resolution residual echo power spectral density estimate. - View Dependent Claims (6, 7, 8)
-
-
9. A digital filter design method, including the steps of:
-
determining a high frequency-resolution power spectral density estimate from an input signal block;
forming a piece-wise constant power spectral density estimate by averaging power densities within frequency bin segments of said high frequency resolution power spectral density estimate;
determining a piece-wise constant digital filter transfer function using said piece-wise constant power spectral density estimate;
wherein said step of forming a piece-wise constant power spectral density estimate includes adapting the length of individual segments to the shape of said high frequency-resolution power spectral density estimate. - View Dependent Claims (10)
-
-
11. A digital filter design apparatus for noise suppression by spectral subtraction, including:
-
means for determining a high frequency-resolution noisy speech power spectral density estimate from a noisy speech signal block;
means for 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;
means for determining a high frequency-resolution background noise power spectral density estimate from a background noise signal block;
means for 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;
means for 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 back ground noise power spectral density estimate;
means for adapting the length of individual segments to the shape of said high frequency-resolution noisy speech power spectral density estimate; and
means for 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. - View Dependent Claims (12, 13, 14)
-
-
15. A digital filter design apparatus for non-linear echo cancellation, including:
-
means for determining a high frequency-resolution speech power spectral density estimate from a residual echo containing speech signal block;
means for forming a piece-wise constant speech power spectral density estimate by averaging power densities within frequency bin segments of said speech high frequency-resolution power spectral density estimate;
means for determining a high frequency-resolution residual echo power spectral density estimate from an echo signal block;
means for forming a piece-wise constant residual echo power spectral density estimate by averaging power densities within frequency bin segments of said high frequency-resolution residual echo power spectral density estimate;
means for determining a piece-wise constant digital filter transfer function using said piece-wise constant speech power spectral density estimate and said piece-wise constant residual echo power spectral density estimate;
means for adapting the length of individual segments to the shape of said high frequency-resolution speech power spectral density estimate; and
;
means for using the same segments for both said high frequency resolution speech power spectral density estimate and said high frequency resolution residual echo power spectral density estimate. - View Dependent Claims (16, 17, 18)
-
-
19. A digital filter design apparatus, including
means for determining a high frequency-resolution power spectral density estimate from an input signal block; -
means for forming a piece-wise constant power spectral density estimate by averaging power densities within frequency bin segments of said high frequency-resolution power spectral density estimate;
means for determining a piece-wise constant digital filter transfer functions using said piece-wise constant power spectral density estimate; and
means for adapting the length of individual segments to the shape of said high frequency-resolution power spectral density estimate. - View Dependent Claims (20)
-
Specification