Formant tracker
First Claim
1. A formant tracker for receiving an analog signal, said formant tracker comprising:
- means for tracking a pitch associated with the analog signal and generating a fundamental frequency therefrom; and
means operably coupled to the output of said pitch tracking means for receiving the fundamental frequency of the analog signal to determine at least one formant within a frequency spectrum in which the analog signal is found, said formant determining means includingmeans establishing an integer set including a plurality of integers associated with at least a selected frequency range containing said at least one formant and within said frequency spectrum in which the analog signal is found, andmeans for establishing within said integer set over the plurality of integers contained therein an optimal integer for said selected frequency range within said frequency spectrum from said integer set and a bandwidth associated with said optimal integer;
said formant determining means generating said at least one formant in response to the product of said optimal integer and said fundamental frequency.
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Accused Products
Abstract
A formant tracker for receiving an analog speech signal and generating indicia representative of the formant. A pitch tracker determines the fundamental frequency of the analog speech input. The fundamental frequency is used to control a sinusoidal oscillator in the generation of a sinusoidal signal which when combined with the analog speech input generates a convolution over the chosen formant frequency. The process is repeated for each integer multiple of the fundamental frequency, thereby changing the sinusoidal oscillator. The optimal integer multiple is chosen which generates the formant identification. The optimal integer is also used to generate an appropriate bandwidth. Three formant frequency ranges are used to define human speech. The optimal integers for the other two formant identifications and the appropriate bandwidths are similarly determined. The three optimal integer values are combined with the fundamental frequency to get the three formant values and their associated bandwidths. These formant values and their bandwidths together with the fundamental frequency are communicated as output so as to identify in formant form the analog signal.
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Citations
16 Claims
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1. A formant tracker for receiving an analog signal, said formant tracker comprising:
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means for tracking a pitch associated with the analog signal and generating a fundamental frequency therefrom; and means operably coupled to the output of said pitch tracking means for receiving the fundamental frequency of the analog signal to determine at least one formant within a frequency spectrum in which the analog signal is found, said formant determining means including means establishing an integer set including a plurality of integers associated with at least a selected frequency range containing said at least one formant and within said frequency spectrum in which the analog signal is found, and means for establishing within said integer set over the plurality of integers contained therein an optimal integer for said selected frequency range within said frequency spectrum from said integer set and a bandwidth associated with said optimal integer; said formant determining means generating said at least one formant in response to the product of said optimal integer and said fundamental frequency. - View Dependent Claims (2, 3)
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4. A formant tracker for receiving an analog signal, said formant tracker comprising:
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means for tracking a pitch associated with the analog signal and generating a fundamental frequency therefrom; means operably coupled to the output of said pitch tracking means for receiving the fundamental frequency of the analog signal to determine a plurality of formants within a frequency spectrum in which the analog signal is found, said formant determining means including means establishing respective integer sets each of which includes a plurality of integers and associated with different selected frequency ranges containing respective formants and within said frequency spectrum in which the analog signal is found, and means for establishing within each said integer set over the plurality of integers contained therein an optimal integer for said selected frequency range corresponding thereto within said frequency spectrum from said respective integer set and a bandwidth associated with each said optimal integer; said formant determining means generating said plurality of formants in response to the respective products of each of said optimal integers and said fundamental frequency. - View Dependent Claims (5, 6, 7, 8)
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9. Apparatus for generating indicia representative of an analog signal corresonding to human speech, wherein the indicia includes a plurality of formants within different selected frequency ranges of the analog signal, with each of said formants being contained within a different one of said selected frequency ranges and said formants collectively being definitive of human speech, said apparatus comprising:
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means for determining a fundamental frequency from said analog signal; plural formant determining means operably coupled to the output of said fundamental frequency determining means for respectively identifying individual formants within the frequency spectrum in which the analog signal is found as contained within said different selected frequency ranges, each of said formant determining means including means establishing a respective integer set including a plurality of integers associated with a selected frequency range containing a respective formant and within said frequency spectrum in which the analog signal is found, said selected frequency range being different from the selected frequency ranges of the other formant determining means, means for iteratively generating for each of said plurality of integers within said integer set a sinusoidal signal from said fundamental frequency as multiplied by successive ones of said integers during respectively iterations, means for convolving said sinusoidal signal with said analog signal over the respective selected frequency range containing said formant to obtain a convolution having a variable amplitude, and means for choosing an optimal integer for said selected frequency range based upon the maximum amplitude of said convolution; each of said formant determining means generating a respective one of said plurality of formants in response to the respective products of each of said optimal integers and said fundamental frequency; and means for determining respective bandwidths associated with each of said plurality of formants; and output means operably coupled to said fundamental frequency determining means, said plural formant determining means, and said bandwidth determining means for providing said plurality of formants and said bandwidths respectively associated therewith along with said fundamental frequency as indicia representative of said analog signal. - View Dependent Claims (10, 11, 12, 13)
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14. A method of identifying a formant from an analog signal, said method comprising:
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generating a fundamental frequency of the analog signal by tracking a pitch associated with said analog signal; establishing an integer set including a plurality of integers associated with at least a selected frequency range containing at least one formant and within a frequency spectrum in which the analog signal is found; determining an optimal integer within said integer set from the plurality of integers contained therein for said selected frequency range within said frequency spectrum; and generating said at least one formant by obtaining the product of said optimal integer and said fundamental frequency. - View Dependent Claims (15, 16)
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Specification