Abstract:
A voice biometric authentication system and method. An authentication system is provided for authenticating a user of a telephonic device, comprising: a setup system for capturing and storing an authentic user voice sample; a comparison system that compares the authentic user voice sample with an inputted voice sample and generates a comparison result; and a control system for controlling access to the telephonic device, wherein the control system: analyzes the comparison result for an initial inputted voice sample received when a telephone call is initiated; and periodically analyzes comparison results for ongoing inputted voice samples received during the telephone call.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates generally to authenticating a person&#39;s voice for accessing a device, and more specifically relates to a continuous voice authentication system and method for telephonic devices. 
   2. Related Art 
   As new telephony technologies continue to emerge, the ability to authenticate users will become more and more important. For instance, as wireless devices become smaller, they become much easier to steal, misplace or lose. If such devices can only be utilized by authorized users, the owners or service providers of the devices need not be concerned about unauthorized use. In addition to the actual devices themselves, the information being transmitted is also susceptible to unauthorized use. Accordingly, systems are required to ensure that an individual receiving information over a telephone network is authorized to receive it. 
   Numerous technologies exist for utilizing voice recognition to authenticate users. For instance, U.S. Pat. No. 6,393,305 B1, “Secure Wireless Communication User Identification by Voice Recognition,” issued to Ulvinen et al., on May 21, 2002, which is hereby incorporated by reference, discloses a method of authenticating a user of a wireless device using voice recognition. Similarly, U.S. Pat. No. 5,499,288, “Simultaneous Voice Recognition and Verification to Allow Access to Telephone Network Services,” issued to Hunt et al., on Mar. 12, 1996, which is hereby incorporated by reference, discloses a voice recognition system for enabling access to a network by entering a spoken password. 
   While such prior art references address the need for authenticating users of telephonic systems using voice recognition, the authentication processes are limited in that once a user is initially authenticated, no further steps are taken to ensure the validity of the user. Thus, if an unauthorized user could overcome the authentication process once (e.g., by speaking a password in a manner to fool the system), the user would have unimpeded access to use the device or the information available over the network. 
   Accordingly, a need exists for a voice recognition system that provides a higher degree of authentication for users of telephonic systems. 
   SUMMARY OF THE INVENTION 
   The present invention addresses the above-mentioned problems, as well as others, by providing a voice biometric authentication system that continuously analyzes input voice samples for authenticating users of a voice based system. In a first aspect, the invention provides an authentication system for authenticating a user of a telephonic device, comprising: a setup system for capturing and storing an authentic user voice sample; a comparison system that compares the authentic user voice sample with an inputted voice sample and generates a comparison result; and a control system for controlling access to the telephonic device, wherein the control system: analyzes the comparison result for an initial inputted voice sample received when a telephone call is initiated; and periodically analyzes comparison results for ongoing inputted voice samples received during the telephone call. 
   In a second aspect, the invention provides an authentication system for authenticating a plurality of users accessing a conference call, comprising: a setup system for capturing and storing an authentic voice sample for each of the plurality of users; and a control system that controls user access to the conference call based on comparison results of inputted voice samples with the authentic voice samples, wherein the control system includes: a system for analyzing the comparison results for an initial inputted voice sample for a joining user when the joining user joins the conference call; and a system for periodically analyzing comparison results for ongoing inputted voice samples for each user during the conference call. 
   In a third aspect, the invention provides a method for authenticating a user of a telephonic device, comprising: capturing and storing an authentic voice sample for the user; initiating a telephone call on the telephonic device; comparing an initial inputted voice sample with the authentic voice sample; deciding whether to terminate the telephone based on the compare step for the initial inputted voice sample; periodically comparing ongoing inputted voice samples obtained during the telephone call with the authentic voice sample; and deciding whether to terminate the telephone based on the periodic compare step for the ongoing inputted voice samples. 
   In a fourth aspect, the invention provides a method for authenticating a plurality of users accessing a conference call, comprising: capturing and storing an authentic voice sample for each user; initiating access of a joining user to the conference call; comparing an initial inputted voice sample of the joining user with the authentic voice samples; deciding whether to allow access to the conference call based on the compare step for the joining user; periodically comparing ongoing inputted voice samples for all joined users obtained during the conference call with the authentic voice samples; and deciding whether to terminate access to the conference call for any of the joined users based on the periodic compare step. 
   In a fifth aspect, the invention provides an authentication system for authenticating a user of a voice processing system, comprising: a setup system for capturing and storing an authentic user voice sample; a system for obtaining inputted voice samples; a comparison system that compares the authentic user voice sample with an inputted voice sample and generates a comparison result; and a control system for controlling access to a device associated with the voice processing system, wherein the control system periodically analyzes comparison results generated for ongoing inputted voice samples in order to continuously control access to the device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings in which: 
       FIG. 1  depicts a telephone system having a voice biometric authentication system in accordance with the present invention. 
       FIG. 2  depicts a flow diagram for authenticating a cell phone user in accordance with the present invention. 
       FIG. 3  depicts a flow diagram for authenticating conference call users in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings,  FIG. 1  depicts a telephone system  10  having a voice biometric authentication system (VBAS)  11  for authenticating users of telephone system  10 . Telephone system  10  may comprise any type of telephonic device through which voice information can be communicated, including, e.g., a wireless or cellular phone, a satellite phone, a multi-user phone system such as a company-based phone system, a conference call system, a land-line based telephone, an internet telephone, a network, etc. Note that while the invention is described herein with reference to a telephone system, the biometric authentication features and concepts described herein could be embodied in any voice processing system. For instance, the voice biometric authentication system of the present invention could be embedded in a smartcard that included an embedded voice biometrics reader to aurally authenticate the holder of the card. 
   Set-up 
   As an initial step, VBAS  11  must first store one or more authentic voice samples  35  that can later be used as a reference to determine authenticity of the user. In the exemplary embodiment of  FIG. 1 , telephone system  10  includes a set-up system  12  having a reference voice sampler  14  for capturing and sampling one or more authentic voice inputs  34  for each authorized user of the telephone system  10 . Captured authentic voice inputs  34  are then stored as authentic voice samples  35  in storage device  16 . In an exemplary embodiment involving a cellular phone, authentic voice samples  35  can be captured and stored by an authorized user by, e.g., speaking a phrase into the receiver during a set-up procedure. The digital signature of each authorized user can then be stored in the existing hardware of the cell phone. In another exemplary embodiment involving a multi-user phone system, authentic voice samples  35  for each authorized user can be stored in a central location or server utilized by the phone system (e.g., similar to a voice mail system). Obviously, any method for capturing and storing authentic voice samples could be utilized with departing from the scope of the invention. 
   Once the set-up is complete and an authentic voice sample  35  is stored for each authorized user, any individual, or group attempting to utilize the telephone system  10  can be authenticated. If authentication fails, access to telephone system  10  can be denied or terminated, e.g., by denying access to a feature, by terminating the call, removing the individual from a conference call, etc. 
   Authentication 
   In order to authenticate users, VBAS  11  includes an input voice sampler  20  for receiving and sampling conversation input  36 ; voice biometric comparison system  18  for comparing inputted voice samples with authentic voice samples  35 ; and a control system  26  for analyzing comparison results  32  from voice biometric comparison system  18 . 
   Input voice sampler  20  may include: (1) an initial voice sampler  22  for sampling an initial conversation utterance from a user, and (2) a periodic voice sampler  24  for sampling ongoing conversation input from the user. (The input voice sampler  20  may be implemented together with the reference voice sampler  14 .) The initial conversation utterance can comprise any initial voice input, such as the first few words spoken by the user, or a code word or phrase spoken by the user. Ongoing conversation input generally comprises aural information spoken by the user during the lifetime of the conversation. Periodic voice sampler  24  can collect input voice samples at any interval, or in any manner, e.g., every N seconds, each time the user speaks, etc. 
   After an input voice sample is collected, it is passed to voice biometric comparison system  18 . Generally, each voice has its own unique signature measurable in frequency and amplitude. Voice biometric analysis is a fairly well developed field, and techniques for comparing signatures are known in the art. Voice biometric comparison system  18  can utilize any known or later developed mechanism, system or algorithm for comparing the input voice sample of the user with the authentic voice sample(s)  35  saved in storage  16 . In the exemplary embodiment, voice biometric comparison system  18  generates comparison results  32  for each compare. Comparison results  32  can comprise any type of information that reflects the analytical results of comparing two voice samples. Possible result formats may include a binary outcome such as “match” or “no-match”; a raw score indicating a probability of a match, such as “70% match”; an error condition, such as “invalid sample”; etc. 
   Comparison results  32  are forwarded to control system  26 . Control system  26  includes an analysis system  28  that examines the comparison results  32  and either allows the call to proceed or terminates the call (or denies access to the call) using termination system  30 . An important aspect of the invention is the fact that authentication of the user is continuous. Specifically, because the control system  26  receives ongoing or periodic comparison results  32  for the accessing user, the control system  26  is able to terminate access to the system  10  at any time during the conversation. Thus, while an unauthorized user may be able to trick the system to gain initial access, ongoing access can be terminated at any time during the call if one of the ongoing inputted voice samples fails to match one of the authentic voice samples  35 . 
   Analysis system  28  may include various modules for analyzing or responding to comparison results  32 . For instance, in the case of an initial inputted voice sample, the analysis system  28  may cause an additional voice sample to be collected and analyzed in the event of a “no-match” situation. Alternatively, analysis system  28  may simply cause access to the telephone system  10  to be denied. 
   In the case of ongoing inputted voice samples, analysis system  28  may collect and analyze multiple, or a series of, comparison results  32 . Thus, the analysis system  28  can achieve a much higher level of confidence in authenticating a user. For instance, analysis system  28  could average probability scores for a set of comparison results  32 . The average could then be compared to a threshold value to determine whether or not to terminate access. 
   Assume an average probability score of 0.75 is required to maintain access to telephone system  10 , and voice comparison system  18  generated a set of comparison results  32  for five sequential inputted voice samples as follow: R 1 =0.7, R 2 =0.6, R 3 =0.9, R 4 =0.9, and R 5 =0.9. The average value would be 0.8, which would pass the threshold of 0.75, indicating a “match” situation. Note however that if only result R 1  or R 2  were used, a “no-match” situation would arise, potentially resulting in an unwarranted denial of access. It should be recognized that any algorithm or system for analyzing a set or series of comparison results could be utilized without departing from the scope of the invention. 
     FIG. 2  depicts a flow diagram for a method of making a telephone call from a cell phone utilizing the principals of the present invention. It is assumed that the cell phone has already been through the set-up procedure and an authorized voice sample has been stored. At step S 1 , the call is initiated. Next, at step S 2 , an initial voice sample is inputted into the receiver of the phone. At step S 3 , the initial voice sample is compared to the authorized voice sample and access is denied at step S 4  if they do not match. If they do match, access to the cell phone is allowed, and the conversation begins at step S 5 . 
   During the conversation an ongoing voice sample is obtained at step S 6 . At step S 7 , the ongoing voice sample is compared to the authorized voice sample. If a match does not exist, further access is terminated at step S 8 . Otherwise, logic flows back to step S 6 , where the sample and test procedures of steps S 6  and S 7  are continuously repeated during the conversation. Accordingly, a continuous authorization process is provided. 
     FIG. 3  depicts a flow diagram for a method of making an N-way conference call utilizing the principals of the present invention. It is assumed that the phone system has already been through the set-up procedure and each of N authorized voice samples have been stored. At step S 10 , the N-way call is started, and an input voice sample # 1  for the first participant is captured at step S 11 . At step S 12 , a test occurs to determine if input voice sample # 1  matches one of the authorized voice samples. If no match is found, access for the first participant is terminated at step S 13 . If a match is found, the first participant is allowed access to the conference call at step S 14 . 
   Next, at step S 15 , an input voice sample #n is captured for the nth participant. At step S 16 , a test occurs to determine if input voice sample #n matches one of the authorized voice samples. If no match is found, access for the nth participant is terminated at step S 17 . If a match is found, the nth participant is allowed access to the conference call at step S 18 . Subsequently, the logic continuously repeats for each of the n participants to ensure that each is an authorized participant throughout the course of the conference call, thus providing continuous testing throughout the conference call. 
   It is understood that the systems, functions, mechanisms, methods, and modules described herein can be implemented in hardware, software, or a combination of hardware and software. They may be implemented by any type of computer system or other apparatus adapted for carrying out the methods described herein. A typical combination of hardware and software could be a general-purpose computer system with a computer program that, when loaded and executed, controls the computer system such that it carries out the methods described herein. Alternatively, a specific use computer, containing specialized hardware for carrying out one or more of the functional tasks of the invention could be utilized. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods and functions described herein, and which—when loaded in a computer system—is able to carry out these methods and functions. Computer program, software program, program, program product, or software, in the present context mean any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: (a) conversion to another language, code or notation; and/or (b) reproduction in a different material form. 
   The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teachings. Such modifications and variations that are apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.