Method and apparatus for judging voiced and unvoiced conditions of speech signal

Claim 3

The method according to claim 1 wherein said parameter is a normalized value φ(T)/φ(o) of the autocorrelation function at a delay time T corresponding to the pitch period of the speech signal.

Claim 4

The method according to claim 1 wherein said parameter is the normalized value W(T)/W(o) at a delay time T corresponding to the pitch period of the autocorrelation function of the residual signal obtainable by a linear predictive analysis of the speech signal.

Claim 5

The method according to claim 1 wherein said parameter is the value of the average magnitude difference function at a delay time T corresponding to the pitch period obtainable by a linear predictive analysis of the speech signal.

Claim 16

Apparatus for judging voiced and unvoiced conditions of a speech signal, comprising means for deriving a signal representative of a ratio k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for deriving a signal representative of a parameter ρ m extracted from the speech signal by correlation technique and representing the degree of the periodicity of the speech signal, means for combining said k 1 ratio signal with said ρ m signal to derive a resultant signal and means for comparing the resultant signal to a threshold signal t determined by the maximum value of the autocorrelation coefficient of the parameter ρ m when the ratio k 1 is equal to zero to judge whether the speech signal is in a voiced condition or an unvoiced conditon.

Claim 17

Apparatus for judging voiced and unvoiced conditions of a speech signal, comprising means for deriving a signal representative of a ratio k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for deriving a signal representative of a parameter ρ m extracted from the speech signal by correlation technique and representing the degree of the periodicity of the speech signal, means for combining said k 1 ratio signal with said ρ m signal to derive a resultant signal and means for comparing the resultant signal to a threshold signal t determined by the maximum value of the autocorrelation coefficient of the parameter ρ m when the ratio k 1 is equal to zero to judge whether the speech signal is in a voiced condition or an unvoiced conditon.

Claim 18

Apparatus for judging voiced and unvoiced conditions of a speech signal comprising means for deriving a signal representative of a ratio k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at a zero delay time and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for multiplying said k 1 signal with a constant a to obtain a product, means for adding said product to a signal ρ m representative of the normalized value φ(T)/φ(o) of the autocorrelation function of the speech signal at a delay time T corresponding to the pitch period of the speech signal to obtain a sum signal, and means for comparing said sum signal with a predetermined threshold signal t determined by the maximum value of the autocorrelation coefficient of the speech signal when the ratio k 1 is equal to zero to thereby judge whether the speech signal is in an unvoiced condition if said sum is smaller than said threshold value and that the speech signal is in a voiced condition if the said sum is larger than said threshold value.

Claim 19

Apparatus for judging voiced and unvoiced conditions of a speech signal comprising means for deriving a signal representative of a ratio k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at a zero delay time and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for multiplying said k 1 signal with a constant a to obtain a product, means for adding said product to a signal ρ m representative of the normalized value φ(T)/φ(o) of the autocorrelation function of the speech signal at a delay time T corresponding to the pitch period of the speech signal to obtain a sum signal, and means for comparing said sum signal with a predetermined threshold signal t determined by the maximum value of the autocorrelation coefficient of the speech signal when the ratio k 1 is equal to zero to thereby judge whether the speech signal is in an unvoiced condition if said sum is smaller than said threshold value and that the speech signal is in a voiced condition if the said sum is larger than said threshold value.

Claim 20

Apparatus for judging voiced and unvoiced conditions of a speech signal, comprising means for deriving a signal representative of a ratio k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at a zero delay time, and the value φ(τs) of the autocorrelation coefficient of the speech signal at a delay time τs of a sampling period, means for multiplying said k 1 signal with a signal representative of a normalized value W(T)/W(o) of the autocorrelation function at a delay time T corresponding to the pitch period of the residual signal to obtain a product signal, and means for comparing the product signal with a predetermined threshold signal t determined by the maximum value of the autocorrelation coefficient of the residual signal when the ratio k 1 is equal to zero to thereby judge whether the speech signal is in an unvoiced condition if said product signal is smaller than said threshold signal and that the speech signal is in a voiced condition if the product signal is larger than said threshold signal.

Claim 21

Apparatus for judging voiced and unvoiced conditions of a speech signal, comprising means for deriving a signal representative of a ratio k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at a zero delay time, and the value φ(τs) of the autocorrelation coefficient of the speech signal at a delay time τs of a sampling period, means for multiplying said k 1 signal with a signal representative of a normalized value W(T)/W(o) of the autocorrelation function at a delay time T corresponding to the pitch period of the residual signal to obtain a product signal, and means for comparing the product signal with a predetermined threshold signal t determined by the maximum value of the autocorrelation coefficient of the residual signal when the ratio k 1 is equal to zero to thereby judge whether the speech signal is in an unvoiced condition if said product signal is smaller than said threshold signal and that the speech signal is in a voiced condition if the product signal is larger than said threshold signal.

Claim 22

Apparatus for judging voiced and unvoiced condition of a speech signal, comprising means for deriving a signal k 1 representative of a ratio φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of a speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for multiplying said ratio signal k 1 with a constant b to obtain a product signal, adding said product signal with a signal representative of the normalized value W(T)/W(o) of the autocorrelation function at a delay time T corresponding to the pitch period of a residual signal obtained by a linear predictive analysis of the speech signal to thereby obtain a sum signal, and means for comparing said sum signal with a predetermined threshold value t determined by the maximum value of the autocorrelation coefficient of the residual signal when the ratio value k 1 is equal to zero to thereby judge whether the speech signal is in an unvoiced condition or the speech signal is in a voiced condition.

Claim 23

Apparatus for judging voiced and unvoiced condition of a speech signal, comprising means for deriving a signal k 1 representative of a ratio φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of a speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for multiplying said ratio signal k 1 with a constant b to obtain a product signal, adding said product signal with a signal representative of the normalized value W(T)/W(o) of the autocorrelation function at a delay time T corresponding to the pitch period of a residual signal obtained by a linear predictive analysis of the speech signal to thereby obtain a sum signal, and means for comparing said sum signal with a predetermined threshold value t determined by the maximum value of the autocorrelation coefficient of the residual signal when the ratio value k 1 is equal to zero to thereby judge whether the speech signal is in an unvoiced condition or the speech signal is in a voiced condition.

Claim 24

Apparatus for judging voiced and unvoiced conditions of a speech signal comprising means for deriving a signal k representative of a ratio φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of a speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time s of a sampling period, means for multiplying said k 1 signal with a signal representative of the normalized value W(T)/W(o) of the autocorrelation function at a delay time T corresponding to the pitch period of a residual signal obtainable by linear predictive analysis of the speech signal to thereby obtain a product signal, means for comparing said product value with a predetermined threshold value t determined by the maximum value of the autocorrelation coefficient of the speech signal under conditions where the ratio value k 1 equals zero to thereby judge whether the speech signal in in an unvoiced condition if said product value is smaller than said threshold value and that the speech signal is in a voiced condition if the product signal is larger than said threshold signal.

Claim 25

Apparatus for judging voiced and unvoiced conditions of a speech signal comprising means for deriving a signal k representative of a ratio φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of a speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time s of a sampling period, means for multiplying said k 1 signal with a signal representative of the normalized value W(T)/W(o) of the autocorrelation function at a delay time T corresponding to the pitch period of a residual signal obtainable by linear predictive analysis of the speech signal to thereby obtain a product signal, means for comparing said product value with a predetermined threshold value t determined by the maximum value of the autocorrelation coefficient of the speech signal under conditions where the ratio value k 1 equals zero to thereby judge whether the speech signal in in an unvoiced condition if said product value is smaller than said threshold value and that the speech signal is in a voiced condition if the product signal is larger than said threshold signal.

Claim 26

Apparatus for judging voiced and unvoiced conditions of a speech signal, comprising means for deriving a signal k representative of a ratio φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of a speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for multiplying said signal k 1 with a constant a to obtain a product signal, means for subtracting said product signal from a signal representative of a parameter extracted from the speech signal by correlation technique and representing the degree of periodicity of the speech signal to derive a difference signal D (τ) representative of the average magnitude difference function of a residual signal obtained by the linear predictive analysis of the speech signal, and means for comparing said difference signal with a predetermined threshold value t determined by the maximum value of the autocorrelation coefficient of the speech signal when the ratio k 1 is equal to zero to judge whether the speech signal is in an unvoiced condition if said difference signal is larger than said threshold value and that the speech signal is in a voiced condition if said difference signal is smaller than said threshold value.

Claim 27

Apparatus for judging voiced and unvoiced conditions of a speech signal, comprising means for deriving a signal k representative of a ratio φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of a speech signal at a zero delay time, and the value φ(τs) of the autocorrelation function of the speech signal at a delay time τs of a sampling period, means for multiplying said signal k 1 with a constant a to obtain a product signal, means for subtracting said product signal from a signal representative of a parameter extracted from the speech signal by correlation technique and representing the degree of periodicity of the speech signal to derive a difference signal D (τ) representative of the average magnitude difference function of a residual signal obtained by the linear predictive analysis of the speech signal, and means for comparing said difference signal with a predetermined threshold value t determined by the maximum value of the autocorrelation coefficient of the speech signal when the ratio k 1 is equal to zero to judge whether the speech signal is in an unvoiced condition if said difference signal is larger than said threshold value and that the speech signal is in a voiced condition if said difference signal is smaller than said threshold value.

Claim 28

Apparatus for judging voiced and unvoiced conditions of a speech signal comprising partial correlation coefficient analyzer means responsive to an input speech signal to be judged for deriving a ratio signal k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at zero dealy time and the value φ(τs) of the autocorrelation function at the speech signal at a delay time τs of the sampling period, pitch period detector means responsive to the autocorrelation function signal values supplied from said partial correlation coefficient analyzer means for extracting by correlation technique a normalized autocorrelation function value signal ρ m representing the degree of periodicity of the speech signal, and voiced/unvoiced detector means responsive to the ratio signal k 1 and the normalized correlation function value signal ρ m for combining said k 1 and ρ m signals and comparing the resultant signal to a threshold signal t determined by the maximum value of the autocorrelation coefficient values of the residual or the speech signals when the ratio signal k 1 = o to thereby judge whether the speech signal is in a voiced or unvoiced condition.

Claim 29

Apparatus for judging voiced and unvoiced conditions of a speech signal comprising partial correlation coefficient analyzer means responsive to an input speech signal to be judged for deriving a ratio signal k 1 = φ(τs)/φ(o) between the value φ(o) of the autocorrelation function of the speech signal at zero dealy time and the value φ(τs) of the autocorrelation function at the speech signal at a delay time τs of the sampling period, pitch period detector means responsive to the autocorrelation function signal values supplied from said partial correlation coefficient analyzer means for extracting by correlation technique a normalized autocorrelation function value signal ρ m representing the degree of periodicity of the speech signal, and voiced/unvoiced detector means responsive to the ratio signal k 1 and the normalized correlation function value signal ρ m for combining said k 1 and ρ m signals and comparing the resultant signal to a threshold signal t determined by the maximum value of the autocorrelation coefficient values of the residual or the speech signals when the ratio signal k 1 = o to thereby judge whether the speech signal is in a voiced or unvoiced condition.

Claim 30

Apparatus according to claim 16 wherein the normalized value signal ρ m is a normalized value of the autocorrelation function value φ(T)/φ(o) of the speech signal at a delay time T corresponding to the pitch period of the speech signal.

Claim 31

Apparatus according to claim 16 wherein the normalized value signal ρ m is a normalized value of the autocorrelation function W.sub.(T) /W.sub.(O) of the residual signal at a delay time T corresponding to the pitch period of the autocorrelation function of the residual signal obtainable by a linear predictive analysis of the speech signal.

Claim 32

Apparatus according to claim 16 wherein the normalized autocorrelation function value signal ρ m is the value of the average magnitude difference function D(τ) of the residual signal at a delay time T corresponding to the pitch period obtainable by a linear predictive analysis of the speech signal.

Claim 33

Apparatus according to claim 17 wherein the voiced/unvoiced detector means includes multiplier means for multiplying the ratio signal k 1 by a constant a representing the slope of a straight line between voiced and unvoiced regions of the speech signal and adder means for adding together the product signal (a × k 1 ) and the normalized autocorrelation function value signal ρ m to derive a resultant signal (a × k 1 ) - ρ m for comparison to the threshold signal t to thereby judge that the speech signal is in an unvoiced condition when the resultant signal is smaller than said threshold signal and that the speech signal is in a voiced condition when the resultant signal is larger than the threshold signal.

Claim 34

Apparatus according to claim 16 wherein the voiced/unvoiced detector means includes multiplier means for multiplying the ratio signal k 1 times the normalized autocorrelation function value signal ρ m and means for comparing the product signal to the threshold signal t to thereby judge that the speech signal is in an unvoiced condition when the product signal is smaller than the threshold signal and in a voiced condition when the product signal is in larger than the threshold signal.

Claim 35

Apparatus according to claim 18 wherein the voiced/unvoiced detector means includes multiplier means for multiplying said k 1 ratio signal with a constant b representing the slope of a straight line between voiced and unvoiced regions of the speech signal to thereby obtain a product signal (b × k 1 ) and adder means for adding the product signal (b × k 1 ) to the normalized autocorrelation function value signal ρ m to derive a resultant signal (b × k 1 ) + ρ m for comparison to the threshold signal t to thereby judge that the speech signal is in an unvoiced condition when the resultant signal is less than t and that the speech signal is in a voiced condition when the resultant signal is greater than t.

Claim 36

Apparatus according to claim 18 wherein the voiced/unvoiced detector means includes multiplier means for multiplying the ratio signal k 1 times the normalized autocorrelation function value signal ρ m and means for comparing the product signal to the threshold signal t to thereby judge the speech signal is in an unvoiced condition when the product signal is smaller than the threshold signal and in a voiced condition when the product signal is in larger than the threshold signal.

Claim 37

Apparatus according to claim 1 wherein the voiced/unvoiced detector means includes multiplier means for multiplying said k 1 ratio signal by a constant a representing the slope of a straight line be between voiced and unvoiced portions of the speech signal and subtractor means for subtracting the value D(τ) of the average magnitude difference function of the residual signal to obtain a difference signal, and comparison means for comparing the difference signal to the threshold signal t to thereby judge that the speech signal is in an unvoiced condition when said difference signal is larger than the threshold signal and in a voiced condition when the threshold signal is larger than the difference signal.