IDENTITY VERIFICATION BY VOICE SIGNALS IN THE FREQUENCY DOMAIN

• US 3,673,331 A
• Filed: 01/19/1970
• Issued: 06/27/1972
• Est. Priority Date: 01/19/1970
• Status: Expired due to Term

• Current Assignee: Halliburton Company
• Original Assignee: George D. Hair, James U. Kincaid
• Inventors: Hair, George D., Kincaid, James U.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Leaheey, Jon Bradford
• Application Number:
  US05/003,991
• Time in Patent Office: 890 Days
• Field of Search: 179/15A,1VS,15B 340/146.3,148,149,152,153 324/77
• US Class Current: 704/246
• CPC Class Codes: G06F 3/16 Sound input; Sound output speech processing G10L
• CPC Class Codes: G07C 9/257 electronically G07C9/26 takes precedence
• CPC Class Codes: G10L 17/02 Preprocessing operations, e.g. segment selection; Pattern representation or modelling, e.g. based on linear discriminant analysis [LDA] or principal components; Feature selection or extraction

Abstract

Voice verification is accomplished at a plurality of spaced apart facilities each having a plurality of terminals. Multiplexing structure interconnects the terminals through a communications link to a central processing station. Analog reproductions of voices transmitted from the terminals are converted into digital signals. The digital signals are transformed into the frequency domain at the central processing station. Predetermined features of the transformed signals are compared with stored predetermined features of each voice to be verified. A verify or non-verify signal is then transmitted to the particular terminal in response to the comparison of the predetermined features.

Claims

1. A method of voice verification comprising:

converting analog reprEsentations of a voice into digital signals, transforming said digital signals into the frequency domain, comparing predetermined features comprising corresponding points of a spectral estimate of said transformed signals which are characteristic of differences between individual voices with stored predetermined features of the voice to be verified, and generating a verify or non-verify signal in response to the comparison of said predetermined features.

2. The method of claim 1 wherein said step of transforming comprises Fourier transformation.

3. The method of claim 1 wherein said corresponding points comprise selected segments of selected phonemes.

4. A method for verifying the voice of an individual comprising:

converting the voice into analog electrical signals, converting said electrical signals into digital signals, sampling spaced apart portions of said digital signals, Fourier transforming the sampled portions of said digital signals into the frequency domain, smoothing the frequency transformed signals, forming a spectral estimate of the smoothed signals, comparing the spectral estimate with a stored spectral signal representative of the individual, and generating a verify or non-verify signal in response to the comparison.

5. The method of claim 4 wherein said Fourier transforming utilizes the Cooley-Tuckey algorithm.

6. The method of claim 4 wherein said step of smoothing comprises:

convolving a real smoothing function with said frequency transformed signals.

7. The method of claim 4 wherein said step of forming a spectral estimate comprises:

multiplying the smoothed signals by the complex conjugate of said signals.

8. The method of claim 4 wherein said step of comparing comprises:

computing a non-negative single valued function of the Euclidian distance between vectors corresponding to said spectral estimate and said stored spectral signal.

9. The method of claim 8 an further comprising:

generating a verify signal only if said non-negative single valued function of the Euclidian distance is equal to or less than a preset threshold value.

10. The method of claim 4 and further comprising:

updating said stored spectral signal in response to variations in said spectral estimate and said stored spectral signal.

11. A method of voice verification for a plurality of stations comprising:

transmitting station and person identification signals from a station to a central processing station, in response to said identification signals generating signals representative of a predetermined series of words to be spoken by the identified person, displaying the series of words to the identified person, transmitting spoken words by the identified person to said processing station, comparing said spoken words with stored representations of the words previously spoken by the identified person, and transmitting verification signals in response to the comparison to the station.

12. The method of claim 11 wherein said station and person identification signals are transmitted in response to insertion of a uniquely coded card into a station.

13. The method of claim 12 wherein said station and person identification signals are transmitted in response to operation of numerical registers at the station.

14. The method of claim 12 wherein said predetermined series of words are visually displayed from a panel at the station in a random manner.

15. The method of claim 12 and further comprising:

transmitting additional numerical signals from a station to the central processing station, wherein operations may be performed thereon if the identity of the person is verified.

16. A system for voice verification comprising:

means for converting analog reproductions of a voice into digital signals, means for transforming said digital signals into the frequency domain, means for comparing predeteRmined features of said transformed signals which are characteristic of differences between individual voices with stored predetermined features of the voice to be verified, fast Fourier transformation means for transforming said digital signals into the frequency domain, means for forming a spectral estimate of points of selected phonemes of said digital signals, and means for comparing the Euclidian distance between points of said spectral estimate and corresponding points of said stored predetermined features, and means for generating a verify or non-verify signal in response to the comparison of said predetermined features.

17. A system for voice verification comprising:

means for converting analog reproductions of a voice into digital signals, means for transforming said digital signals into the frequency domain, means for comparing predetermined features of said transformed signals which are characteristic of differences between individual voices with stored predetermined features of the voice to be verified, means for generating a verify or non-verify signal in response to the comparison of said predetermined features, and means for varying the stored predetermined features in response to the comparison of said predetermined features.

18. A system for verifying the voice of an individual comprising:

means for converting the voice into analog electrical signals, means for converting said electrical signals into digital signals, means for sampling spaced apart portions of said digital signals, Fourier transform means for transforming the sampled portions of said digital signals into the frequency domain, means for smoothing the frequency transformed signals, means for forming a spectral estimate of the smoothed signals, means for comparing the spectral estimate with a stored spectral signal representative of the individual, and means for generating a verify or non-verify signal in response to the comparison.

19. The system of claim 18 wherein said Fourier transform means operates according to the Cooley-Tukey algorithm.

20. The system of claim 18 wherein said means for smoothing comprises:

means for convolving a real smoothing function with said frequency transformed signals.

21. The system of claim 18 wherein said means for forming a spectral estimate comprises:

means for multiplying the smoothed signals by the complex conjugate of said signals.

22. The system of claim 18 wherein said means for comparing comprises:

means for computing a non-negative single valued function of the Euclidian distance between vectors corresponding to said spectral estimate and said stored spectral signal.

23. The system of claim 22 and further comprising:

means for generating a verify signal only if said non-negative single valued function of the Euclidian distance is equal to or less than a preset threshold value.

24. The system of claim 18 and further comprising:

means for updating said stored spectral signal in response to variations in said spectral estimate and said stored spectral signal.

25. A system for voice verification comprising:

a plurality of spaced apart facilities each requiring verification of the identities of a predetermined group of people, each facility having a plurality of terminals for receiving identification and voice information and for indicating verification signals, multiplexing means interconnecting the terminals at each facility to a communications link, a central processing station for receiving and transmitting signals over the communications link, means at said central processing station responsive to identification information from a terminal for requesting voice information at said terminal, frequency conversion means at said central processing station for converting voice information transmitted from said terminal into the frequency domain, means at said centraL processing station for comparing the frequency converted information with stored identification information, and means for generating verification signals for transmission to said terminal in response to said comparison.

26. The system of claim 25 wherein each of said terminals at a facility are connected via wirelines to said multiplexer.

27. The system of claim 25 wherein said communications link comprises an electromagnetic wave communication system.

28. The system of claim 25 and further comprising:

reversible multiplexer means located at said central processing station.

29. The system of claim 25 and further comprising:

gate means at said terminals for allowing entrance only upon the receipt of favorable verification signals.

30. In a system for voice verification, the combination comprising:

a terminal for connection through a communications link with a central voice verification station, means at said terminal for transmitting a unique identification signal representative of an individual to the central station, display means at said terminal responsive to a control signal from the central station for displaying in random order a plurality of required words to be spoken by the individual, microphone means at said terminal for transmitting the spoken required words to the central station, and means at said terminal for indicating verification signals transmitted from the central station in response to the spoken required words.

31. The combination of claim 30 wherein said display means comprises:

a panel located on said terminal and including a plurality of selectively energizable word display portions,said control signal sequentially energizing said portions in a random order to reduce the possibility of fraudulent operation of the system.

32. The combination of claim 31 and further comprising:

keyboard means disposed on said terminal to enable the transmission of supplemental information to the central station.

33. The combination of claim 30 wherein said means for transmitting a unique identification signal comprises circuitry responsive to the insertion of a coded card.

34. The combination of claim 30 wherein said means for transmitting a unique identification signal comprises selectively operable register means disposed for manual operation on said terminal.

35. The combination of claim 30 wherein said means for indicating verification signals includes means for controlling the unlatching of a passageway.

36. The combination of claim 30 wherein said means for indicating verification signals energizes a visual sign.