Abstract:
A method and apparatus providing a telephone user with a manner in which to send DTMF commands during a call over a communication network by use of a speech-based user interface. The user speaks one or more words corresponding to DTMF commands, and the invention performs speech recognition on the spoken words, generates corresponding DTMF signals, and transmits the DTMF signals over the network.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of telecommunications and more particularly to a method and apparatus for transmitting Dual Tone Multi-frequency (DTMF) signals to an automated system responsive to touch-tone control thereof by using a speech-based user interface. 
     BACKGROUND OF THE INVENTION 
     The use of automated DTMF (i.e., touch-tone) controlled systems is now common throughout much of the industrialized world and still increasing. Such systems are employed for a variety of reasons, including to provide greater convenience to users (e.g., automated after hours services) and to reduce the need for human telephone operators. For example, some mail order companies with limited customer service hours use an automated after-hours system that allows a customer to check on the status of an order 24 hours a day. The customer navigates the automated system by pressing keys on the phone keypad to send DTMF commands in response to a recorded menu of options. However, many telephones of both traditional wireline and the wireless variety (i.e., cordless, cellular, PCS, or satellite) provide the keypad within the handset, thereby making it very inconvenient for the user to send DTMF commands while listening for responses from the automated system. To press a key, the user has to remove the phone from his or her ear to look at the keypad and then return the phone to the ear again to hear the next prompt. During a call in which a number of such commands must be sent to an automated system the user must repeat this back and forth motion frequently. 
     Advances in speech recognition technology over the years have made possible some improvements in the way users submit commands to automated DTMF-controlled systems. For example, some automated DTMF-controlled systems themselves allow the user to speak commands instead of pressing keys on the keypad. In such systems, the user is told, “Press or say ‘9’,” for example. Another approach is to provide an intermediate server in the network between the user and the automated response system to convert spoken commands to DTMF signals, which are then relayed to the automated response system. One disadvantage of this approach, however, is that the user must first call the intermediate server, which in turn calls the desired automated DTMF-controlled system. Sometimes the user does not know a priori whether or not a commercial entity has an automated DTMF-controlled system. Also, users may not want to go through the extra time and steps of dialing an intermediate speech-to-DTMF server. 
     Another manner in which speech recognition technology is used to facilitate the sending of DTMF commands is in voice dialing, a method in which a user may dial a telephone number by speaking the number instead of pressing keys on a keypad. In some implementations this capability even extends to simple spoken labels that represent a number such as “home” to represent user&#39;s home telephone number. This capability may be implemented in either the local terminal or in the network. Once dialing is complete, however, the speech recognition function is turned off, and the speech-to-DTMF capability is not available to the user during a call for use with automated systems responsive to touch-tone control. 
     SUMMARY OF THE INVENTION 
     It is a first object of the present invention, therefore, to provide a speech-based user interface for transmitting DTMF signals during a telephone call to automated systems that can be controlled by DTMF signals. A second object of the invention is to provide such a speech-based user interface without requiring the user to have a priori knowledge of the automated DTMF-controlled system and without the user having to access an intermediate server in the network to access the speech-to-DTMF conversion capability. A third object is to provide the user with simple control over the speech recognition aspect of the invention. Finally, it is an object of the present invention to provide the user with the capability of transmitting multiple DTMF commands with a single activation of the speech recognition circuit. 
     The invention satisfies these objects by providing a telephone apparatus and associated method. The apparatus comprises a microphone for receiving spoken utterances from a user, a speech recognition circuit, and a DTMF signal generator. When the user speaks an utterance corresponding to a DTMF command that the user wants to transmit over a communication network, the speech recognition circuit analyzes the spoken utterance to determine whether or not it matches one of a predetermined set of DTMF commands. If so, the DTMF signal generator outputs the corresponding DTMF signal for transmission over the communication network. 
     In a further embodiment of the present invention, the speech recognition circuit is activated by a push button switch located on the telephone. In another alternative embodiment, the speech recognition circuit responds to a predetermined activation utterance from the user by activating the conversion and transmission of spoken DTMF commands. In yet another embodiment, the user receives confirmation of recognized words via speech synthesis and has the opportunity to cancel the transmission of an incorrect DTMF command. 
     These and other objects of the invention, together with features and advantages therefore, will become apparent from the following detailed specification when read with the accompanying drawings in which like reference numerals refer to like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, reference is made to the following Detailed Description taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a simplified circuit block diagram of one embodiment of the present invention. 
     FIG. 2 is a flowchart illustrating the operation of the circuit block diagram shown in FIG.  1 . 
     FIG. 3 is a flowchart illustrating an alternative operation of the circuit block diagram shown in FIG.  1 . 
     FIG. 4 is a simplified circuit block diagram of another embodiment of the present invention. 
     FIG. 5 is a flowchart illustrating the operation of the circuit block diagram shown in FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, FIG. 1 shows a simplified circuit block diagram of an embodiment of the invention. In this embodiment, the invention resides in a communication device such as a cellular telephone, satellite phone, cordless phone, personal digital assistant (PDA), palmtop computer, or laptop computer equipped with a wireless modem, collectively referred hereafter as a “telephone”  100 . The telephone  100  includes a push button switch  110  conveniently located so the user may press it while holding the telephone  100  to his or her ear. When a user presses push button switch  110  momentarily, controller  120  asserts enable line  125  to enable a speech recognition circuit  130 . Also, the controller  120  activates a tone generator  140 . The output of tone generator  140  is fed to an audio output stage  150 , which in turn drives a speaker  160 . The audible tone is used to signal the user that the speech recognition circuit  130  is ready to accept spoken utterances. Other audible tones of the same or different frequency may be used at other times to signal that word recognition has failed or that the recognition and transmission of a DTMF command was successful. 
     The speech recognition circuit  130  receives the user&#39;s spoken utterances which have been converted to electrical form by microphone  170 . The output  135  of the speech recognition circuit  130  is fed to the controller  120 . If the speech recognition circuit  130  reports that an utterance spoken by the user corresponds to a DTMF command, the controller  120  uses control bus  122  to cause the DTMF signal generator  180  to generate the associated DTMF signal, which is transmitted by RF transmitter  190  over a wireless communication network via antenna  195 . 
     The speech recognition circuit  130  is preferably of the type that does not require prior training to recognize utterances spoken by a particular individual. The speech recognition circuit is also adapted to recognize a small input vocabulary of spoken utterances comprising word names corresponding to the digits “0” through “9”, “#”, “*”, and the word names of the letters “A” through “Z”. For example, a vocabulary such as “one,” “two,” “three,” “four,” “five,” “six,” “seven,” “eight,” “nine,” “star,” “asterisk,” “pound,” “number,” and “A” through “Z” is sufficient for most applications involving DTMF commands. 
     In an alternative embodiment, the telephone  100  does not include push button switch  110 . Instead, the speech recognition circuit  130  responds to a predetermined activation utterance from the user to prepare the speech recognition circuit  130  to receive a spoken utterance corresponding to one of the predetermined set of DTMF commands. In this embodiment, the user might speak, for example, a unique and perhaps unusual word or sound such as “shazam,” then “five” to send a DTMF command for the digit “5” over the network. 
     The operation of the simplified circuit block diagram of FIG. 1 is illustrated in FIG.  2 . This method corresponds to the apparatus in FIG.  1 . Referring to FIGS. 1 and 2, the process begins at inquiry step  210 , in which the user&#39;s press of the push button switch  110  is awaited. Once push button switch  110  is pressed, an audible tone (e.g., a beep) is emitted through the telephone speaker at step  220  to indicate to the user that the speech recognition circuit  130  is ready to accept user input, and the speech recognition circuit  130  is enabled at step  230 . At this point, a timing loop  240  measures the interval from when the speech recognizer  130  was enabled until a spoken utterance is received from the user over microphone  170 . If no spoken utterance is received within a predetermined period, a silence timeout occurs, and processing proceeds to step  250 , in which a distinct audible tone is emitted indicating that no spoken word was recognized and that the speech recognition circuit  130  has been disabled. If the user speaks a sound prior to the timing loop  240  registering a silence timeout, the speech recognition circuit  130  processes electrical input from microphone  170  at step  260  to identify the spoken word. If the spoken utterance is not recognized as belonging to the defined vocabulary (digits “0” through “9”, “#”, “*”, or one of the alphabetic characters “A” through “Z”, for example), processing proceeds to step  250  described above. If the spoken utterance is recognized as a valid command at inquiry step  260 , the corresponding DTMF signal is generated and transmitted in step  270 . Finally, at step  280 , an audible tone is again emitted to inform the user that speech-to-DTMF conversion was successful. 
     In an alternative embodiment, the invention is capable of handling multiple DTMF commands with only a single activation step from the user. The method of this embodiment may be practiced using the apparatus of FIG. 1 with minor modifications in the operations carried out by controller  120 . Referring to FIGS. 1 and 3, the process is initiated at inquiry step  310  by the user pressing the push button  110 . An audible tone is output to the user at step  320  to indicate the speech recognition circuit  130  is ready to receive input, and the speech recognition circuit  130  is enabled at step  330 . If the user speaks an utterance before timing loop  340  measures a period of silence exceeding a predetermined silence threshold, the identified word is queued in step  350 , and processing returns to step  330  in which the speech recognizer is enabled for the recognition of a new spoken utterance. Processing continues in this looping manner from steps  330  through  350  until timeout loop  340  measures an interval of silence greater exceeding a predetermined duration. Thus, the user can send a DTMF command such as “157” in one step by use of this method. The user presses the push button switch  110 , listens for the audible tone, speaks the digits “1”, “3”, and “7”, each separated by a brief period of silence, and pauses after the last digit until the silence timeout occurs. 
     Once the timing loop  340  has measured a silence timeout, the controller  120  checks to determine whether at least one valid DTMF command word was recognized at inquiry step  360 . If not, a distinct beep is output to the user at step  370  indicating failure. Step  370  is also executed if a spoken utterance from the user does not match the defined vocabulary of speech recognition circuit  130 . If one or more valid words corresponding to DTMF commands were recognized, the corresponding DTMF command or commands are generated and transmitted over the network at step  380 . Finally, an audible beep is again output to the user at step  390  to inform the user that speech-to-DTMF conversion was successful. In an alternative implementation of this embodiment, each individual DTMF command in a set of multiple DTMF commands is generated and sent immediately rather than being queued until all DTMF commands have been received. 
     The embodiment providing for multiple DTMF commands with a single activation of the speech recognition circuit  130  (see FIG. 3) may also be combined with the embodiment described above in which an activation utterance from the user alerts the speech recognizer  130  to expect DTMF command input in the next spoken utterance from the user. In this case, the speech recognition circuit  130  responds to a specific, predetermined activation utterance to signify that the next spoken utterance from the user will correspond to a DTMF command, as described above. 
     An alternative embodiment of the telephone  100  is shown in the simplified circuit block diagram of FIG.  4 . This embodiment is similar to that of FIG. 1, except that this embodiment further includes a simple speech synthesizer comprising a digital-to-analog converter (D/A)  410  connected to a waveform memory  420 . When the user speaks an utterance that the user desires to transmit as a DTMF command, a speech waveform corresponding to the spoken word recognized by the speech recognition circuit  130  is played from the waveform memory  420  through digital-to-analog converter  410  to the user through speaker  160 . This confirms to the user that the recognized word is the one intended. If not, the user has the option of canceling the transmission, either by pressing push button switch  110  again within a predetermined period or not pressing it within a predetermined period, depending on the implementation of this feature. 
     FIG. 5 is a flowchart of the operation of the simplified circuit block diagram shown in FIG.  4 . This embodiment is especially useful when reliability is essential, such as banking transactions, in which an incorrect command sent from the user could have serious and undesirable consequences. The operation of this embodiment corresponds closely to that of FIG. 2, except that a speech waveform corresponding to the spoken word recognized by the speech recognition circuit  130  is played to the user from waveform memory  420  through digital-to-analog converter  410  through speaker  160  in step  510  of FIG.  5 . In the preferred form of this embodiment, the user must press push button switch  110  again within a predetermined period (e.g., one second) to confirm the correctness of the speech recognition and authorize transmission of the DTMF signal (see step  520 ). 
     Alternatively, the user can press push button switch  110  again to cancel transmission. In this case, the command is considered confirmed automatically if the user does nothing within the predetermined period. 
     Another alternative implementation of the confirmation step is for speech recognition circuit  130  to respond to a predetermined confirmation utterance spoken by the user. This implementation is consistent with the embodiment described above in which a predetermined activation utterance prepares the speech recognizer circuit  130  to receive spoken utterances corresponding to DTMF commands. For example, a user might speak “shazam” to activate the speech recognition circuit  130 , then “seven” to send a “7” as a DTMF command. When the speech synthesizer plays back the recognized utterance “seven,” the user then says “okay” to confirm the transmission of the corresponding DTMF signal. 
     The embodiment illustrated in FIGS. 4 and 5 may also be combined with the alternative method of FIG. 3 to provide for the transmission of multiple DTMF commands with a single activation of speech recognition circuit  130 . In this case, confirmation via speech synthesis is preferably delayed until all spoken commands have been recognized. In other words, all recognized digits are played back to the user in succession after all input spoken utterances have been recognized rather than immediately upon recognition of each individual utterance. 
     While the present invention has been described with respect to a few preferred embodiments, it will be appreciated by those of ordinary skill in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential character thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive.