Adaptive speaker verification apparatus and method including alternative access control

A useful, novel, and nonobvious speech verification apparatus, method and media incorporating the same, as well as a secure interactive voice response ("IVR") system. The speaker verification apparatus and method involves a determination whether one or more speech samples captured from a speaker substantially matches a speaker template in a registration database. If no substantial match is found, alternate access control is utilized to allow the speaker to verify herself, without the use of speaker verification techniques. If alternative access control is able to verify the speaker, the captured speech samples are used to modify the corresponding speaker template. The so-modified speaker template may account for acoustic idiosyncrasies or anomalies perceived in the speech samples to improve verification rates in subsequent acoustic attempts.

FIELD OF INVENTION 
This invention is directed to speaker verification through analysis of 
captured speech samples, and is particularly concerned with improving 
speaker verification rates where the speaker requests verification in 
different acoustic environments. 
DESCRIPTION OF THE RELATED ART 
Interactive voice response ("IVR") systems often collect data in 
conjunction with a telephone call. The data may include information such 
as an account number or social security number. This data may be used to 
retrieve information from a secure server related to the caller. 
Since the server data is typically confidential and/or personal in nature 
(e.g. bank records, credit rating, voice mail messages, etc.), most IVR 
systems implement an access control process to prevent unauthorized 
callers from gaining wrongful access to the server data and/or secure 
portions of the IVR system. In the past, this access control process 
typically involved the caller verifying her identity through keying in a 
series of DTMF digits (e.g. an authorization or personal identification 
"PIN" code) from her telephone keypad in response to appropriate prompts 
orchestrated by the access control process. While such keypresses and 
codes are easy to discern and verify, it is difficult for callers to 
always remember the correct sequence and may be inconvenient to punch it 
in, especially when one of the caller's hands is already being used to 
support the telephone handset. 
This problem has been exacerbated by the influx of secure access home and 
office automation tools into the market place. Many of these require 
dissimilar types of authorization code sequencing. As result, users 
wishing secure access are faced with either committing a long list of 
authorization codes to memory, or carrying around PIN code cheat-sheets 
which undermines the security and ease-of-use features these tools 
allegedly offer. 
In response, industry has sought alternative means to offer convenient yet 
secure access control. Since most IVR systems are telephony based, 
acoustic speaker verification appears to be a natural access control 
candidate. Such acoustic speaker verification, in which the speaker speaks 
a predetermined "password" word or phrase that is compared against a 
registration database of speaker templates, offers reasonably secure 
access control, especially when sophisticated template matching techniques 
are utilized. Moreover, the caller wishing to be verified need only do 
what comes naturally over the telephone (speak a predetermined password 
when prompted by the IVR system rather than attempt to punch in an 
authorization code on a keypad). 
However, acoustic speaker verification has not been widely pursued as an 
access control technique because of difficulties faced in handling speech 
variations stemming from changing acoustic environments the speaker is 
speaking from, and even tone or pronunciation variations of the speaker 
herself. As defined herein, the acoustic environment includes the ambient 
environment in which the speaker resides, the perceivable background noise 
emanating from that environment, the voice acquisition and transmission 
quality of intervening communications equipment, and the like. 
While conventional speaker identification algorithms are quite 
sophisticated in comparing captured speech samples to speaker templates, 
Applicants perceive the weak link to be conventional treatment of the 
speaker templates of the registration database. Heretofore, the speaker 
templates of the authorization or registration database remained static 
from their initial creation, or if modified, became largely unmodifiable 
after the first few verification iterations due to template convergence 
effects of known template modification techniques. Where the speaker 
template remains static, the speaker will always be compared against a 
speaker template created within a specific acoustic environment which may 
be acoustically dissimilar from which the speaker is currently calling 
from. Due to the inherent noise sensitivity of known speaker 
identification techniques, a registered speaker may be improperly denied 
access because the acoustic environment in which the pre-established 
password is spoken (e.g. a public phone in a crowded airport concourse) 
does not match the acoustic environment (e.g. a quiet branch office using 
a digital PBX extension) in which the template was created. Although 
several static templates can be defined for each registered speaker, 
accurate verification still relies in part on predicting what kind of 
environment the speaker will be calling from, which in practical terms 
becomes an arduous task in our increasingly mobile society. 
As mentioned previously, conventional adaptive speaker verification 
techniques involve "near static" templates, since they are designed to 
quickly converge towards a template result typically after only four to 
eight verification operations from template creation. This is ostensibly 
done to circumvent long training or break-in periods otherwise required in 
obtaining reasonably accurate speaker verification rates. While improved 
over use of static speaker template comparison since some degree of 
adaptation is allowed, the caller still is required to call in from 
dissimilar acoustic environments early in the template definition and 
modification process in order to improve verification rates when calling 
from different acoustic environments. 
Therefore, it would be desirable to provide a speaker verification 
apparatus or method which can adapt registered speaker templates to 
changing acoustic environments without the aforementioned convergence 
issues. It would also be desirable that a way be provided to verify the 
identity of the speaker through an alternative access control process when 
speaker identification fails due to present acoustic environment and/or 
changes in the speaker's voices. Finally, it would be desirable to provide 
an adaptive speaker verification apparatus or method that can be easily 
implemented in a wide range of secure automation tools and devices. 
SUMMARY OF THE INVENTION 
In accordance with these and related desires, the present invention is 
directed to a useful, novel, and nonobvious speech verification apparatus, 
method and media incorporating the same, as well as a secure interactive 
voice response ("IVR") system including such speech verification 
apparatus. Speaker verification according to the present invention 
involves a determination whether one or more speech samples captured from 
a speaker substantially matches a speaker template in a registration 
database. If no substantial match is found, alternate access control is 
utilized to allow the speaker to verify herself, potentially without the 
use of speaker recognition techniques. If alternative access control is 
able to verify the speaker, the captured speech samples are used to modify 
the corresponding speaker template. The so-modified speaker template may 
account for incorporate acoustic idiosyncrasies or anomalies perceived in 
the speech samples to improve verification rates in subsequent iterations. 
Preferably, this alternative access process involves an interactive keypad 
or keyboard-based session that allows the speaker to communicate access 
information such as a password to the speaker verification apparatus or 
method without requiring further speech capture and template analysis. 
This feature is advantageous in that the speaker is presented with a 
familiar, if less desirable way to input access information that is 
significantly less dependent on the speaker's momentary voice 
characteristics or acoustic environment in which she is communicating. 
Further, preferably, alternative access control should be able to verify 
the speaker using access information corresponding to converted speech to 
text versions of the templates stored in the registration database. This 
feature enhances verification ease-of-use since a common password or 
phrase can be used by the speaker for verification purposes, whether or 
not template matching is successful. 
Further, according to speaker verification of the present invention, 
aforementioned template matching may include using a combination of speech 
recognition and acoustic speaker recognition techniques. 
Other aspects and features of the present invention will become apparent to 
those ordinarily skilled in the art upon review of the following 
description of the specific preferred embodiments of the invention in 
conjunction with the accompanying figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the following detailed description, references are made to the 
accompanying drawings which form a part hereof and in which is shown by 
way of illustration specific embodiments in which the invention may be 
practiced. These embodiments are described in sufficient detail to enable 
those ordinarily skilled in the art to practice the invention, and it is 
to be understood that other embodiments may be utilized and that 
structural, logical, and electrical changes may be made without departing 
from the spirit and scope of the present invention. The following detailed 
description is, therefore, not to be taken in a limiting sense, and the 
scope of the present invention is to be defined only by the appended 
claims. 
An interactive voice response system including the speaker verification 
unit according to the first embodiment of the invention is shown generally 
at 170 in FIG. 1. The system comprises a secure server 110 coupled to a 
telephone switch 100, such as a private branch exchange ("PBX") switch 
having an interface into the server 110 thereby enabling the server in the 
switch to communicate information identifying telephone connections in a 
known manner. In this embodiment, the switch preferably comprises a Nortel 
Meridian 1 Switch available through Northern Telecom Limited of Montreal, 
Quebec, Canada. The secure server 110 is also networked to the personal 
computer indicated at 150. The network 180 can be one of many commercially 
available networks, such as Ethernet, with higher level network software 
comprising Novell Netware or Microsoft NT, for example. Although not shown 
in the Figure, network 180 can be organized as a LAN or WAN with links to 
the Internet, as is well understood in the art. 
The personal computer 150 is represented in block format for convenience, 
and herein comprises an industry standard general purpose digital computer 
including a processor, random access memory (RAM), and one or more 
secondary storage devices such as hard disk drives, CD ROMs, and 
diskettes. In addition, it contains a network card to establish a 
bi-directional communications link with the secure server 110 via the 
network 180. Secure server 110 may also be a standard personal computer, 
but usually has more secondary storage and RAM to enable it to store large 
amounts of data for the personal computer attached to it as well as 
information to which an incoming caller desires access. Both the server 
110 and computer 150 store software and execute it on processors from RAM. 
In the embodiment of FIG. 1, computer 150 comprises an interactive voice 
response ("IVR") system which may be a stand alone device which answers 
incoming calls from callers utilizing local digital extension 120 or 
remote telephone 130 coupled to PBX 100 through the Public Switched 
Telephone Network ("PSTN") 140. Alternatively, the computer 150 may 
comprise a single board computer installed within PBX 100 and/or secure 
server 110. In such case, it may have less memory and local storage 
options than a general purpose PC, but is more tightly integrated with the 
PBX and can more easily leverage PBX resources, so that it can still 
implement the IVR system including the speaker verification unit 160 
according to the present embodiment. 
It should be realized here that local digital extension 120 as well as 
remote telephone 130 comprise conventional telephony devices having both 
voice and at least dual tone multi-frequency (DTMF) signaling capabilities 
initiated through depression of one or more keys of a conventional DTMF 
keypad disposed on each, as is well understood in the art. Accordingly, 
further description is omitted herein. 
The IVR system collects caller/user input and sends user information to the 
secure server 110. Computer 150 also includes a speaker verification unit 
160 according to the present embodiment for verifying the identity of the 
caller calling in from either remote telephone 130 or local extension 120 
to access confidential or sensitive information on the secure server 110 
and/or computer system 150 implementing the IVR response system. 
In this embodiment, the speaker verification unit 160 preferably comprises 
modules or units of programming instructions residing in computer 150 
memory that, when executed by the processor of computer 150, carries out 
speaker verification procedures of the present embodiment described below 
with respect to FIGS. 2 and 3A and 3B. The program statements defining the 
speaker verification unit 160 are usably embodied in a computer-readable 
medium, such as the aforementioned hard disk drive, CD-ROM diskette or 
other storage media (whether accessible locally or remotely through 
network 180) or the aforementioned RAM, as is well understood in the art. 
In other embodiments, the speaker verification unit can also be 
implemented by the preparation of application specific integrated circuits 
or by interconnecting an appropriate network of conventional hardware 
components, devices and circuits or a combination of hardware and software 
components as will be apparent to those ordinarily skilled in the art. 
Further detail of the programming code structure comprising the speaker 
verification unit 160 of FIG. 1 is shown in block diagram form in FIG. 2. 
As is previously stated, such programming code is preferably executed by a 
processor in computer 150 out of RAM. Thus, the blocks in FIG. 2 may be 
loosely thought of as portions of the RAM. However, it is to be understood 
by those skilled in the art that code modules comprising the programming 
code may be stored anywhere in RAM or similar computer readable medium 
locally or remotely accessible to the computer system 150, and the 
functions may be distributed in many different ways within modules without 
departing from the teachings of the invention. 
As shown in FIG. 2, the speaker verification unit according to the present 
embodiment includes a determination unit 200 for capturing speed samples 
acquired from the user and storing them into a temporary buffer 210. Using 
the buffered and captured samples, stored in buffer 210, the determination 
unit 200 communicates with the registration database 250 and compares the 
captured speech samples stored in buffer 210 against the speech templates 
contained in the registration database 250. Based on the results of the 
comparison, the determination unit will either permit caller entry to the 
secure server 110-IVR system 150 or issue a request to the speaker 
identification unit 230 to perform alternate verification (non-speech 
based) verification of the calling party using alternate access unit 220. 
The template modification unit 240 preferably provides code programming 
instructions for the processor of computer 150 to selectively modify 
template entries in the registration database 250 based on the captured 
speech samples contained in buffer 210 when the speaker is verified 
through either determination unit 200 processing or speaker identification 
unit 230 processing in conjunction with alternate access unit 220. Turning 
briefly to FIG. 5, FIG. 5 is a block diagram depicting the internal 
organization of the registration database 250 according to the first 
embodiment of the invention. Each entry 550 of the database 250 includes 
registered speaker information 560 as well as a speech template 570 and 
template text conversion data 580 as indicated in the figure. Here, 
preferably, template 510 of each database entry 550 comprises a model that 
an incoming speech segment is compared against to determine if the speaker 
of the incoming segment is likely to be the same speaker that initially 
created the template. Speaker verification is well known in the art, and 
although there are many variations, speech verification systems have a 
core similarity. In the usual situation, the user articulates a number 
(generally three to eight) of distinct examples of the word or phrase used 
as a password. The password is preferably a relatively long word or a 
phrase so as to ensure sufficient information and redundancy. Appropriate 
signal processing is done on the articulation so as to extract the desired 
acoustic features. Then, an appropriate selection is made of those 
features that are desirable. Finally, a pattern classifier is defined to 
integrate the selected features into a particular space. A threshold is 
then determined that allows the system to separate the appropriate space 
into two categories: "Accept" (the new incoming example is likely to be 
from the speaker who created the model) or "Reject" (the new incoming 
example is unlikely to be from that speaker). Many variations are possible 
for implementing the feature extraction, feature selection, and 
classification. A Fast Fourier Transform can be performed that provides a 
matrix of signal energy levels for a number of frequency bands (e.g., 
eight) crossed by time (e.g., every 15 mS). A model template could thus be 
created by simply averaging these values across all of the samples, and 
then using an algorithm that sums the differences between energy levels 
for each element of the matrix to result in a single numerical score 
reflecting the quality of the match. A threshold is then selected, using 
the variations among the training samples as a guide to expected 
variation. More sophisticated systems may use speech features such as 
pitch that require additional levels of processing and may use decision 
criteria that weight different speech features differently. Some systems 
may use neural networks for the classification and feature selection 
stages, with either conventional feature extractors or neural network 
feature extractors used. Neural networks have the advantage that a 
learning algorithm (e.g., backward propagation) is used to automatically 
create a general model, given a set of examples. A neural network also has 
the ability to determine optimum differential weightings for different 
features and to do this weighting with higher-order factors, not just 
linear. 
Although not shown in the FIG. 5, each registered speaker may have a 
plurality of speaker templates and associated template text defined in the 
registration database 250. 
FIGS. 3A and 3B are related flowcharts detailing speech verification 
processing carried out by the speech verification unit 160, including the 
determination unit 200, the speaker identification unit 230, the alternate 
access control unit 220, and the template modification unit 240 components 
thereof, according to the first embodiment of the invention. Referring 
first to FIG. 3A , speech verification processing according to the present 
embodiment begins at step S300 wherein an iteration index i is 
initialized. The iteration index is used to track the number of times the 
speaker has attempted speaker verification using a spoken pre-established 
password. Control thereafter passes to step S310 in which the speaker or 
caller is prompted for the pre-established password. 
Control thereafter passes to step S315 in which a determination is made as 
to whether the user has depressed a DTMF key (indicating she wants to 
bypass acoustic speaker verification). If so, control passes to step S318, 
in which alternate access control processing procedures are invoked using 
alternate access control unit 220 and as detailed herein below with 
reference to FIG. 3B. Control thereafter terminates naturally. Otherwise, 
control passes to step S320, in which the speech sample preferably 
consisting of a word, phrase or utterance is stored in the determination 
unit buffer 210. Thereafter in step S330, the speech sample stored is in 
buffer 210 including the current speech sample just captured in step S320 
is recognition processed using known speaker-dependent or 
speaker-independent speech recognition techniques. It should be recognized 
that the speech recognition processing step S330 here serves as a first 
pass filtration mechanism used to isolate those entries 550 in the 
registration database 250 whose speaker templates 510 are phonemically 
similar to the captured speech sample. This first pass greatly reduces the 
pool of potential registration database speaker templates 510 which must 
be compared against the captured speech sample using below-described 
speaker verification techniques which, in turn, greatly simplifies 
processing and improves performance over known single-pass verification 
techniques. 
Still referring to FIG. 3A, control thereafter passes to step S360. In step 
S360, the speech verification unit 160 of the present embodiment compares 
the current captured speech samples to the templates isolated during the 
aforementioned speech recognition step S330 using known speaker 
verification techniques. As is well understood in the art, such speaker 
verification techniques can be used to generate confidence levels 
associated with each captured speech sample-speaker template comparison. 
Also, although not preferred, conventional speaker identification 
techniques could be used to generate these confidence match levels. Then, 
the speech verification unit 160 will select the closest match based on 
the so-generated confidence levels and threshold it against a 
predetermined threshold to determine whether in fact verification has 
occurred. 
Control thereafter passes to step S370 in which the determination is made 
whether a template match has been found. If no match has been found, 
control passes to step S410, in which the iteration counter (i) is 
incremented and then control passes to step S420. At step S420, a 
determination is made whether the incremented iteration counter exceeds 
the preferably pre-established limit for allowing speaker verification 
attempts. If that limit has been exceeded, meaning in this embodiment that 
the caller has used up his chances for gaining access through acoustic 
speech verification, control passes to step S430. At step S430, the speech 
verification unit undertakes alternate access processing as specified in 
the alternate access control unit 220 (FIG. 2) and as detailed below with 
reference to the flow diagram of FIG. 3B. Control thereafter terminates 
naturally. 
If, however, in step S420, the determination is made that the incremented 
iteration index does not exceed the pre-established limit, indicating that 
the caller has not yet squandered his chances for speaker verification, 
control instead passes to step S450 in which the speaker is notified that 
the speech verification unit 160 is unable to verify her identity based on 
the captured speech samples and to instruct the speaker to retry speaking 
the pre-established password. Control thereafter leaps back to step S310, 
in which the speaker verification unit again issues a request prompting 
the speaker for the pre-established password. 
If, however, in step S370, a determination has made that a template match 
has been indicated using the aforementioned speaker identification 
techniques, control instead passes to step S380. In step S380, the status 
of the iteration counter is queried to see whether more than one set of 
speech samples has been stored in the buffer 210 of the determination unit 
200 shown in FIG. 2. In this embodiment, if at least two distinct speech 
samples are captured in the buffer 210, control passes to step S390, in 
which the speaker template found a match the current speech sample is 
modified using the speech samples stored in buffer 210. 
According to the present embodiment, the template or templates of the 
matched registered user will be modified by the captured speech samples by 
one of a variety of methods. One method is simply to recompute the model 
using the existing samples and the new sample pooled together, as if all 
samples were present at the initial time of registration. Since this is 
typically computationally intensive, this is typically done by queuing up 
the samples and performing the processing when there is no load on the 
computer 150 processor from ongoing calls. Other methods use feature 
extraction algorithms that create a standard set of parameters for each 
sample, and maintain a template that consists of the "average" set of 
parameters for all samples, and where it is easy to modify the template by 
(for example, recomputing a mean) using only the parameters and not having 
to redo the signal processing for all of the original samples. Note that 
if more than one reference template has been defined for a particular 
individual, the template with the closest match is chosen to be modified. 
Once template modification in step S380 has been performed, control within 
the speaker verification unit 160 passes to step S400 in which access is 
granted to the secure areas of the IVR system executing on computer 150 or 
the secure server 110 as identified in FIG. 1. Control thereafter 
terminates naturally. 
If, however, a determination is made in step S380 that the iteration index 
counter is 1, meaning that the only one speech sample is contained in the 
buffer 210, control instead passes to step S400 without the aforementioned 
template modification being performed. This is because a successful match 
was made the first time, suggesting that the matched speaker template 
accounts for present acoustic environment the registered speaker is 
speaking from. Control thereafter terminates naturally. 
Referring now to FIG. 3B, FIG. 3B is a flow diagram illustrating an example 
access control process carried out by the speech verification unit 160 of 
the present embodiment. When alternate access processing is requested in 
step S430 (FIG. 3B) control begins at step S432 in which a second 
iterative index counter is initialized. This second iterative counter (i) 
is used to trace the number of times that the speaker has attempted 
verification through the alternative access control technique. 
Control thereafter passes to step S434, in which the speaker is prompted 
for a typed version of the pre-established password by prompting the 
speaker therefor. By accepting a typed version of the pre-established 
password, the speaker need only remember one password in order to gain 
access to the secure areas of the server 110 and/or the IVR system 
executing on computer system 150 through either access control process. 
Control thereafter passes to step S436 in which the speaker verification 
unit 160 attempts to capture keypad entry performed by the caller on the 
DTMF keypad associated with the extension 120 or phone 130 (FIG. 1) that 
the caller is using. Control thereafter passes to step S438. At step S438, 
a determination is made whether the captured key pad entries, preferably 
comprising a DTMF sequence, match template text values 580 contained in 
the registration database. In this embodiment, the DTMF tone sequences are 
converted into their corresponding alphanumeric combinations and then 
these combinations are compared against the template text values 580 
stored in the registration database in order to perceive a match. If 
template text matching the keypad entry is not found in the registration 
database, control passes to step S440, in which the second iteration 
counter is incremented and control passes to step S442. In step S442, the 
determination is made whether the caller has exceeded a preferably 
predetermined number of attempts for keying in the typed version password. 
This limit should be less than the speaker verification attempt limit 
described to increase security. If the limit has been exceeded, control 
passes to step S444, wherein the caller is denied access and processing by 
the speaker verification unit terminates naturally. 
If, however, in step S442 a determination is made that the second iteration 
index counter has yet to exceed the predetermined attempt limit, control 
instead passes to step S446 wherein a message is relayed to the speaker to 
retry typing in the registered password. Control is thereafter passes to 
step S434 in which the speaker is prompted for typing in the version of 
the pre-established password and keyboard capture is again attempted as 
described hereinabove. 
If, however, in step S438 it is determined that a match has been made, 
control jumps to step S380 (FIG. 3A). If, in step S380, it is determined 
that the first iterative index (i)&gt;1, it is presumed that at least one 
prior acoustic speaker verification iteration had been attempted without 
success. Accordingly, control passes to step S390 where the captured 
speech sample or samples stored in buffer 210 are used to modify the 
speaker template(s) defined for the registered speaker, identified in step 
S438. It should be noted that the captured speech samples failing acoustic 
verification will be used to alter the speech template of this registered 
speaker to accommodate the noise or acoustic anomalies perceived in the 
captured speech samples to improve future verification rates. Control then 
passes to step S400, in which the user is permitted access to the secure 
areas of the IVR system of computer 150 or the secure server 110. 
Thereafter, speech verification processing according to the present 
embodiment terminates naturally. 
If, however, in step S380 it is determined that i=1, it is presumed that 
the user has bypassed acoustic speaker verification according to the 
present embodiment and has instead chosen to verify exclusively through 
the alternate access control procedures. Since the speaker was 
successfully identified in step S438 without acoustic verification being 
attempted, control passes to step S400 directly without the need for 
speaker template modification discussed hereinabove. Thereafter, speech 
verification processing according to the present embodiment terminates 
naturally. 
FIG. 4 depicts a block diagram of portable information processor 400 such 
as a multimedia laptop computer or personal digital assistant ("PDA") 
implementing speaker verification according to a second embodiment of the 
invention. Information processor 400 includes bus 430, CPU 410 coupled to 
bus 430, primary memory 420 coupled to bus 430, sound interface 440 in 
communication with bus 430 and also being coupled to microphone 450 and 
speaker 460, and drive interface 470 in communication with bus 430 and 
also being coupled to secondary storage drive 480 capable of accessing 
data and instructions stored on a hard disk, or removable media such as 
floppy 490 and CD-ROM 500. Information processor also includes network 
interface 510 coupled to bus 430 for interconnecting the information 
processor 400 to a network 520, such as LAN, WAN or the Internet. 
In this embodiment, bus 430, CPU 410, memory 420, sound interface 440, 
microphone 450, speaker 460, drive interface 470, secondary storage drive 
480, floppy 490, CD-ROM 500, and network interface 510 are conventional 
computer components generally known in the art. Thus, such components will 
not be further described herein except as to amplify upon the principles 
of the present invention. 
In this embodiment, like the previous embodiment, the operational 
components defining the speaker verification unit 160 are carried out by a 
central processing unit 410 executing corresponding instructions in memory 
420, which preferably comprises RAM or EEPROM. In fact, those speech 
verification unit 160 components shown and discussed hereinabove with 
reference to the memory map of FIG. 2 and whose operations are detailed 
hereinabove with respect to FIGS. 3A and 3B will be preferably 
incorporated into the memory 420 of the present embodiment. Alternatively, 
these speech verification components may be usably embodied in a removable 
or fixed computer-readable medium such as CD-ROM 500, a hard disk, or 
floppy disk 490 located within information processor 400 or accessible 
thereto via network 520. 
Unlike the first embodiment, speech samples can be captured directly from 
the speaker using microphone 450 and sound interface 440, and prompts can 
be directly issued to the speaker using acoustic speaker 460. Moreover, 
the speaker verification unit, as part of the portable information 
processor 400, can be carried to the acoustic environment in which the 
speaker seeking verification to secure access to the processor 400, 
thereby reducing the chances for transmission anomalies from interfering 
with the verification process. 
While the invention is described above in terms of specific preferred 
embodiments and associated drawings, those of ordinary skill in the art 
will recognize that the invention can be practiced in other embodiments as 
well. It is felt therefore that the invention should not be limited to the 
disclosed embodiments, but rather should be limited only by the spirit and 
scope of the appended claims.