Abstract:
The invention is directed to techniques for suppressing the voice of a user of an audio electronic device, such as a mobile phone, from being heard by an unintended listener. In one arrangement, the invention includes an input microphone, an electronics module, and a suppression speaker. The user speaks into the input microphone, and the electronics module generates an antivoice signal from a voice signal received from the input microphone. The suppression speaker outputs an antivoice output that combines with the voice of the user to form a voice suppression zone next to the speaker. The user thus can carry on his or her conversation in private as long as the unintended listener is within the voice suppression zone. Alternately, the user can avoid distracting other users of similar devices nearby, such as in a crowded office environment with many individuals using telephones at the same time. In another arrangement, the invention includes multiple suppression speakers that can be oriented in different directions to provide one or more voice suppression zones.

Description:
BACKGROUND OF THE INVENTION 
   Telephone technology provides users of the phone with a readily available means of communicating over long distances. A typical telephone or other audio communication device provides a microphone that the user speaks into, a communication link between the user and another party, and a speaker that provides the other party&#39;s voice to the user. Over time, audio communication technology has come to include mobile phones, such as cellular phones, satellite phones, and other devices. 
   Noise cancellation techniques exist to reduce unwanted noise that may interfere with audio communication, such as unwanted noise that interferes with a user listening to another party on a telephone or a headset device. Active noise reduction (ANR) techniques provide a sound wave that is out of phase with the unwanted noise. For example, in an airplane, an ANR technique provides an antinoise sound wave designed to mask or greatly reduce the noise of jet engines so that pilots or passengers in the airplane may use headsets in the airplane without distraction. The ANR technique includes using a microphone to detect a sound, such as the jet engine, electronic circuitry to produce an antinoise sound wave opposite in phase to the noise, and a speaker to broadcast the antinoise sound wave into or near a user&#39;s ear, such as through a headset that the user is wearing or from a location near the user&#39;s ear. The antinoise sound wave destructively interferes with the noise. The result is the reduction of the noise to a more comfortable level for the user. 
   SUMMARY OF THE INVENTION 
   At times, when talking on a mobile phone or other audio communication device, users desire to have a private conversation without strangers overhearing them. For example, an individual may use a cellular phone in a crowded airport, where finding a private room or space is difficult, if not impossible. The user of the cellular phone can turn to face a wall or corner of the room, but a stranger nearby may still overhear the conversation. The user may resort to various strategies, such as referring to topics in a cryptic or clipped manner or speaking in a very soft tone, but these approaches may interfere with the flow of the conversation with the party on the other end of the conversation. Such users desire to have a mobile phone that they can speak into privately and carry on conversations freely without being heard by unintended listeners that the user does not want to overhear the conversation. These same concerns apply to any number of audio electronic devices, such as two-way radios, personal tape recorders, laptop computers, and other devices used in the presence of such unintended listeners. 
   In other situations, users are distracted by conversations occurring near them, such as in a telemarketing office environment, where many workers carry on phone conversations in small cubicles adjacent to each other. Such workers desire to have a less distracting and noisy environment where they may concentrate on their own conversations. Such concerns apply to any environment where workers use telephones in cubicles, where enclosed offices are not available to most workers. In this situation, workers desire to suppress the noise of other conversations so that they may concentrate more effectively on their own work. 
   Thus, there is a need to eliminate or suppress unwanted voices overheard by unintended listeners, both from the standpoint of the users of an audio electronic device and unintended listeners seeking to avoid a distraction. 
   The invention thus provides a way to suppress the voice of the user of an audio electronic device. The invention provides a separate voice suppression speaker that projects an antivoice output directed outwardly away from the audio electronic device into a suppression zone where the antivoice output destructively interferes with the voice of the user. An unintended listener in the voice suppression zone hears a reduced voice that is difficult to hear clearly or understand. The audio electronic device can also include two or more voice suppression speakers which have different orientations from each other. 
   In one embodiment, an audio electronic device comprises an audio privacy feature for suppressing a voice, including an input microphone, an electronics module, and a suppression speaker. The input microphone generates a voice signal in response to a voice input. The electronics module receives the voice signal from the input microphone and generates an antivoice signal based on the voice signal. The suppression speaker receives the antivoice signal from the electronics module and generates an antivoice output from the antivoice signal. The antivoice output combines with the voice to form a voice suppression zone adjacent to the suppression speaker. In the voice suppression zone, the voice is attenuated so that it is difficult to understand by a listener located in the voice suppression zone. 
   The electronics module also includes, in another arrangement, an inverter and a delay module. The inverter inverts the voice signal into the antivoice signal so that the antivoice signal is opposite in phase to the voice signal. The delay module introduces a delay in the antivoice signal so that the antivoice output generated from the delayed antivoice signal is opposite in phase to the voice input. 
   In one arrangement, the delay introduced by the delay module is based on the distance from the input microphone to the suppression speaker. In another arrangement, the delay module controls the length of the signal based on a feedback signal. In alternate arrangements, the feedback signal is based on the antivoice signal or the antivoice output. If based on the antivoice output, the audio electronics device further includes a feedback microphone that receives the antivoice output. 
   Another arrangement of the audio electronics device includes a transmitter, a receiver, and a personal speaker for the user of the device to that the device can communicate with other devices. In other arrangements, the audio electronic device is a phone device, such as a wireless, hand-held phone, or a computerized device. 
   In one embodiment, an audio electronic device comprises an audio privacy feature for suppressing a voice, including an input microphone, an electronics module, and suppression speakers. The input microphone generates a voice signal in response to a voice input. The electronics module receives the voice signal from the input microphone and generates an antivoice signal based on the voice signal. The suppression speakers receive the antivoice signal from the electronics module and generate an antivoice outputs from the antivoice signal. The antivoice outputs combine with the voice to form one or more voice suppression zones adjacent to the suppression speakers. In each voice suppression zone, the voice is attenuated so that it is difficult to understand by a listener located in the voice suppression zone. 
   In one arrangement, the electronics module includes an inverter and a delay module. The inverter inverts the voice signal into the antivoice signal so that the antivoice signal is opposite in phase to the voice signal. The delay module introduces a delay in the antivoice signal so that the antivoice outputs generated from the delayed antivoice signal are opposite in phase to the voice input. 
   In one embodiment, an electronics module for use in a privacy device suppressing a voice includes a voice signal input, an antivoice signal output, and a controller. The controller receives the voice signal from the voice signal input and generates the antivoice signal based on the voice signal. The antivoice signal enables a suppression speaker to generate an antivoice output based on the antivoice signal that combines with the voice to form a suppression zone adjacent to the suppression speaker. 
   In one arrangement, the electronics module also includes a delay module. The controller inverts the voice signal into the antivoice signal so that the antivoice signal is opposite in phase to the voice signal. The delay module introduces a delay in the antivoice signal so that the antivoice output is opposite in phase to the voice input. 
   Another arrangement of the electronics module includes a feedback signal input receiving a feedback signal representative of the delayed antivoice signal. 
   In a further arrangement, the antivoice signal is a digital signal and the electronics modules includes a shift register and a digital-to-analog converter. The shift register introduces the delay into the digital antivoice signal. The digital-to-analog converter generates an analog antivoice signal from the delayed digital voice signal. In another arrangement, the antivoice signal is an analog signal, and the electronics module includes an analog-to digital-converter. 
   In another embodiment, the invention is a method for suppressing a voice received by an unintended listener to the voice. The method includes providing a voice signal based on the voice of a user, generating an antivoice signal based on the voice signal, and generating an antivoice output based on the antivoice signal that combines with the voice in order to suppress the voice received by the unintended listener located in a voice suppression zone formed by the antivoice output. 
   In one arrangement, the method includes inverting the voice signal to provide the antivoice signal so that the antivoice signal is opposite in phase to the voice signal, adding a delay to the antivoice signal, and generating the antivoice output based on the delayed antivoice signal. 
   The method also includes in another arrangement determining the delay based on the distance from the location of voice input to the location of the antivoice output. In one arrangement, this distance is the distance from the input microphone to the suppression speaker. 
   In another arrangement, the method includes controlling the length of the delay in the antivoice signal based on a feedback signal. In alternate arrangements, the feedback signal is based on the antivoice signal or the antivoice output. 
   In a further arrangement, the method includes orienting a direction of the antivoice output to direct the voice suppression zone to encompass a target location. 
   Another embodiment of the invention is directed to a computer program product that includes a computer readable medium having instructions stored thereon for suppressing a voice received by an unintended listener to the voice. The instructions cause a computer to receive a voice signal based on the voice of a user, generate an antivoice signal based on the voice signal, and output the antivoice signal so that the antivoice signal enables the generating of an antivoice output based on the antivoice signal that combines with the voice in order to suppress the voice received by the unintended listener located in a voice suppression zone formed by the antivoice output. 
   In one arrangement, the instructions cause the computer to invert the voice signal to provide the antivoice signal so that the antivoice signal is opposite in phase to the voice signal, add a delay to the antivoice signal, and generate the antivoice output based on the delayed antivoice signal. 
   A further embodiment of the invention is directed to a computer program propagated signal product that is embodied in a propagated medium having instructions stored thereon for suppressing a voice received by an unintended listener to the voice. For example, the propagated signal can be a radio signal carried by a radio wave, or an electrical signal propagated over the Internet or other network. The instructions cause a computer to receive a voice signal based on the voice of a user, generate an antivoice signal based on the voice signal, and output the antivoice signal so that the antivoice signal enables the generating of the antivoice output based on the antivoice signal that combines with the voice in order to suppress the voice received by the unintended listener located in a voice suppression zone formed by the antivoice output. 
   In one arrangement, the instructions cause the computer to invert the voice signal to provide the antivoice signal so that the antivoice signal is opposite in phase to the voice signal, add a delay to the antivoice signal, and generate the antivoice output based on the delayed antivoice signal. 
   The above-described features of the invention are well suited for use with devices manufactured by Cisco Systems, Inc. of San Jose, Calif. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
       FIG. 1  shows, by way of example only, an overhead view of an audio privacy system including a mobile phone device having an input microphone, an electronics module, a personal speaker, and a suppression speaker generating a voice suppression zone encompassing an unintended listener. 
       FIG. 2  shows a block diagram of an arrangement of an audio electronics device, including an input microphone, an electronics module, a suppression speaker, a feedback microphone, and a voice suppression zone. 
       FIG. 3  provides, by way of example only, a block diagram of an electronics module suitable for use as one instance of the electronics module shown in  FIG. 2 , including a computer having a processor and memory. 
       FIG. 4  shows a flow diagram of a procedure performed by the audio electronic device of  FIG. 2  when in operation. 
       FIG. 5  shows, by way of example only, a block schematic diagram of an arrangement of an electronics module suitable for use in the audio electronics device of  FIG. 2 , including a preamplifier, an inverter, a delay module, and an amplifier. 
       FIG. 6  shows a flow diagram of a procedure performed by the electronics module of  FIG. 5  when in operation. 
       FIG. 7  shows, by way of example only, a block diagram of an arrangement of a delay module suitable for use in the electronics module of  FIG. 5  including an analog-to-digital converter, a delay controller, a shift register, and a digital-to-analog converter. 
       FIG. 8  shows a flow diagram of a procedure performed by the delay module of  FIG. 7  when in operation. 
       FIG. 9  shows, by way of example only, a view of an arrangement of a mobile phone device suitable for use in the audio privacy system shown in  FIG. 1 . 
       FIG. 10  shows, by way of example only, an overhead view of an arrangement of a mobile phone device including a plurality of voice suppression speakers generating a plurality of voice suppression zones. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention is directed to techniques for suppressing the voice of a user of an audio electronic device, such as a mobile phone, to provide privacy for the user of the device and prevent an unintended listener from understanding the message delivered by the voice. The techniques involve generating an antivoice signal based on a voice signal representative of the voice of the user, and then outputting the antivoice signal as an antivoice output that suppresses the voice at the location of the unintended listener. The antivoice output and the voice combine to produce a combined sound that is difficult or impossible for the unintended listener to understand. The techniques include providing plural antivoice outputs oriented in different directions. The above-described features of the invention are well suited for use with devices manufactured by Cisco Systems, Inc. of San Jose, Calif. 
     FIG. 1  shows an audio privacy system  20  that is suitable for use by a user  24  speaking with his or her voice  22  into a mobile phone  28  that may be overheard by an unintended listener  26 . The mobile phone  28  includes a input microphone  30  for receiving a voice input  38  from the mouth  40  of the user  24 , an electronics module  32 , a personal speaker  36  for the user  24 , and a suppression speaker  34  that produces an antivoice output  42  that forms a voice suppression zone  46  adjacent to the suppression speaker  34 . 
   In general, the mobile phone  28  is a moveable or portable mobile radio communication system, such as a cellular phone, cordless phone, or other types. In one arrangement, the mobile phone  28  is a wireless phone device, such as a cellular phone or wireless telephone device, capable of two-way radio communication with other devices, including mobiles phones  28 , of the same type. 
   The voice suppression zone  46  is a three dimensional volume defined by the output of the suppression speaker  34  within which the antivoice output  42  from the suppression speaker  34  combines with the voice  22  to form a suppressed voice output  44 . The voice  22  is suppressed by decreasing the volume of the voice  22 , distorting the voice  22 , or otherwise attenuating the voice  22  to produce a suppressed voice output  44  within the voice suppression zone  46 . Typically, the unintended listener  26  is not able to distinguish the content of any message conveyed by the voice  22 , as long as the unintended listener is located in the voice suppression zone  46 . 
   The boundaries of the voice suppression zone  46  are shown in  FIG. 1  by the zone boundaries  48 - 1  and  48 - 2 , which are not meant to be limiting and are shown by way of example only. The zone boundaries  48 - 1  and  48 - 2  in  FIG. 1  are lines representative of a three dimensional boundary zone beyond which the volume of the antivoice output  42  is at a sufficiently low level so that the antivoice output  42  does not combine effectively with the voice  22  to form the suppressed voice output  44 . In other words, at a location just beyond the boundary  48 - 1  or  48 - 2  and outside of the voice suppression zone  46 , the audio pattern of the voice  22  can be detected as opposed to detecting the audio pattern of the suppressed voice output  44 , which is a combination pattern representing the combined voice  22  and antivoice output  42 . 
   The design of the mobile phone  28  places the input microphone  30  closer to the user&#39;s mouth  40  than the suppression speaker  34 . In a preferred arrangement, the input microphone  30  should be as close to the user&#39;s mouth  40  as possible. The design of the mobile phone  28  also provides a physical separation between the input microphone  30  and the suppression speaker  34  to give the electronics module  32  and the suppression speaker  34  enough time to generate an antivoice output  42 . The mobile phone  28  also provides a limited physical barrier to the voice  22 . 
   The user  24  can also move the voice suppression zone  46  by moving the mobile phone  28  (e.g. by redirecting a hand holding the phone) so as to direct the suppression speaker  34  in a particular direction to encompass an unintended listener  26  located in that direction. In one arrangement, the mobile phone  28  has a movable suppression speaker  34  that the user  24  moves in a particular direction to encompass an unintended listener  26 . 
     FIG. 2  provides further details of the invention and illustrates an audio electronic device  60  suitable for use with the audio privacy system  20  of  FIG. 1 . The audio electronic device  60  includes the input microphone  30 , the electronics module  32 , the suppression speaker  34 , and, optionally, a feedback microphone  74 . The input microphone  30  receives the voice input  38  and outputs a voice signal  62  to a voice signal input  64  on the electronics module  32 . The electronics module  32  outputs the antivoice signal  68  through the antivoice signal output  66  of the electronic module  32  to the suppression speaker  34 . The suppression speaker  34  outputs the antivoice output  42  from the suppression speaker  34  to form a voice suppression zone  46  adjacent to the suppression speaker  34 . The electronics module  32  receives a feedback signal  72 - 1  through the feedback signal input  70 . In one arrangement of the invention, the feedback signal  72 - 1  is a feedback signal  72 - 2  based on the antivoice signal  68 . In an alternate arrangement, the feedback signal  72 - 1  is a feedback signal  72 - 3  received from the feedback microphone  74 , which receives a feedback input  76  based on the antivoice output  42 . 
   The voice input  38  is a sound wave produced by the user  22 , and the antivoice output  42  is a sound wave produced by the suppression speaker  34 . The input microphone  30  and feedback microphone  74  are microphones suitable for use with an audio electronic device  60 , such as microphones used with mobile phones as is known to those skilled in the art. The suppression speaker  34  is a speaker suitable for use with the audio electronic device, such as speakers used with mobile phones as is known to those skilled in the art. 
   In one arrangement, the voice signal  62 , antivoice signal  68 , and feedback signal  72  are implemented as digitized electronic signals. In another arrangement, the voice signal  62 , antivoice signal  68 , and feedback signal  72  are implemented as analog electronic signals. In a further arrangement, one or more of the voice signal  62 , antivoice signal  68 , and feedback signal  72  are implemented as a digital signal and one or more of them are implemented as an analog signal. Correspondingly, in one arrangement, the electronics module  32  and its components are implemented using analog circuitry. In another arrangement, the electronics module  32  and its components are implemented using digital circuitry. In a further arrangement, some components of the electronics module  32  are implemented using analog circuitry and some components are implemented using digital circuitry. Thus, for example, in one arrangement, the electronics module  32  receives an analog voice signal  62  and outputs a digital antivoice signal  68 . 
   In another arrangement, the electronics module  32  is implemented on an integrated circuit (IC), such as an ASIC (application-specific integrated circuit) or other IC, installed on a printed-circuit board (PCB) and in communication with the input microphone  30 , the feedback microphone  74 , and the suppression speaker  34  through PCB connections. The use of an ASIC for the electronics module  32  is efficient in terms of cost and power consumption. 
   The electronics module  32  is implemented as any suitable combination of software instructions and hardware circuitry.  FIG. 3  provides, by way of example only, additional detail for an electronics module  80  suitable for use in one arrangement of the electronics module  32  shown in  FIG. 2 . The electronics module  80  includes a computer  82  including a processor  84  and a memory  86 . The electronics module  80  is capable of executing software instructions implementing all or part of its functionality. 
   In one arrangement, a computer program product  88  including a computer readable medium (e.g. one or more CDROMs, diskettes, tapes, etc.) provides software instructions for all or part of the functionality of the electronics module  80 , which can be installed on the computer  82  in the electronics module  80 . Thus, the electronics module  80  is a combination of the computer  82  with installed software instructions. 
   The computer program product  88  can be installed by any suitable software installation procedure as is well known in the art. For example, in one arrangement, the computer program product is a CDROM, and an external CDROM drive is in electrical communication with the mobile phone  28  by a wire that plugs into a jack in the mobile phone  28 . The user  24  can download a computer program or software application  87  including the software instructions for the electronics module  80  from the computer program product  88  on the CDROM to the computer  82  in the electronics module  80  using the jack in the mobile phone  28 . 
   The software instructions can be downloaded over a wireless connection. A computer program propagated signal product  89  embodied on a propagated signal on a propagation medium (e.g. a radio wave, an infrared wave, a laser wave, sound wave, or an electrical wave propagated over the Internet or other network) provides software instructions for all or part of the functionality of the electronics module  80 . The propagated signal is a signal that can be transmitted over the propagation medium over an extended period of time. In alternate arrangements, the propagated signal is an analog carrier wave or a digital signal carried on the propagated medium. For example, in one arrangement, the propagated signal is a digital signal propagated over the Internet or other network. 
   In another arrangement, the electronics module  80  is part of a mobile phone  28 , and the computer application  87  including the software instructions is downloaded as a computer program propagated signal over the radio wave connection to the mobile phone  28  for installation on the computer  82  in the electronics module  32 . If the mobile phone  28  has a wireless Internet connection, in one arrangement, the computer application  87  including the software instructions is downloaded as a computer program propagated signal from a Web site to the mobile phone  28  for installation in the computer  82  in the electronics module  32 . 
     FIG. 4  provides a flow diagram explaining the procedure  90  performed by the audio electronic device  60  of  FIG. 2  when in operation. In step  92 , the input microphone receives a voice input  38  from a user  24  and generates a voice signal  62  based on the voice input  38 . The electronics module  32  receives the voice signal  62  through the voice signal input  64  of the electronics module  32  and generates an antivoice signal  68  based on the voice signal  62  (step  94 ). In one arrangement, the antivoice signal  68  is opposite in phase to the voice signal  62 . Then the electronics module  32  introduces a delay into the antivoice signal  68  (step  96 ). In one arrangement, the delay is based on the distance from the location of the input microphone  30  to the location of the suppression speaker  34 . In step  96 , the electronics module  32  receives a feedback signal  72 - 1  and uses the feedback signal  72 - 1  to tune the delay in the antivoice signal  68 . In one arrangement, the electronics module  32  controls the length of the delay to insure that the antivoice output  42  based on the antivoice signal is opposite in phase to the voice  22  from the user  24 . As described earlier, the feedback signal  72 - 1  is either a feedback signal  72 - 2  based on the antivoice signal, or a feedback signal  72 - 3  based on feedback input  76 , which is in turn based on the antivoice output  42 . In step  100 , the suppression speaker  34  receives the antivoice signal  68  from the antivoice signal output  66  of the electronics module  32 . Then, the suppression speaker  34  generates an antivoice output  42  based on the antivoice signal  68  (step  102 ). In one arrangement, the feedback microphone  74  converts the feedback input  76  into a feedback signal  72 - 3  (step  104 ), which the electronics module  32  receives as feedback signal  72 - 1  at the feedback input  70  of the electronics module  32  (see step  98 ). The antivoice output  42  forms a voice suppression zone  46  adjacent to the suppression speaker  34  (step  106 ). Within the voice suppression zone  46 , the antivoice output  42  combines with the voice  22  to form a suppressed voice output  44  (see  FIG. 1 ). 
   Another arrangement of the audio electronic device  60  is enabled selectively to suppress a selected voice, sound, or noise, such as to suppress certain distracting sounds or noises produced by the user  24 , and serves as a voice correction device rather than as an audio privacy device. In this case, the user  24  is speaking with an intended listener, not an unintended listener  26 , and the user  24  intends for his message to be heard without distraction. For example, a user  24  with a hacking cough, compulsive sneezing, or other intermittent distracting noise, uses an audio electronic device  60 , which has been programmed to produce antivoice output  42  to suppress the intermittent distracting noise, but not to suppress a normal conversational voice. In this case, the audio electronic device  60  is programmed to recognize a certain voice pattern, such as cough, and enables the antivoice output  42  when that voice pattern occurs. In another arrangement, the audio electronic device  60  includes voice recognition software that learns the patterns of the voice  22  of a user  24 , as is known in the art for voice and speech recognition software. 
   In various arrangements, the electronics module  32  of  FIG. 2  is implemented as analog circuitry, digital circuitry, or a combination of analog and digital circuitry. 
     FIG. 5  provides, by way of example only, additional detail for an electronics module  120  suitable for use with the invention as one instance of the electronics module  32  shown in  FIG. 2 . The electronics module  120  in  FIG. 5  includes a preamplifier  122 , an inverter  124 , a delay module  126 , an amplifier  128 , the voice signal input  64 , the feedback input  70 , and the antivoice signal output  66 . 
     FIG. 6  provides a flow diagram explaining the procedure  140  performed by the electronics module  120  of  FIG. 5 . In step  142 , the preamplifier  122  receives the voice signal  62 - 1  through the voice signal input  64  of the electronics module  120 . The preamplifier  122  amplifies the voice signal  62 - 1  to produce the amplified voice signal  62 - 2  (step  144 ). The inverter  124  generates an antivoice signal  68 - 1  based on the amplified voice signal  62 - 2  by inverting the amplified voice signal  62 - 2  to provide an inverted signal or antivoice signal  68 - 1  which is opposite in phase to the amplified voice signal  62 - 2  (step  146 ). The delay module  126  introduces a delay into the antivoice signal  68 - 1  to produce a delayed antivoice signal  68 - 2  (step  148 ). The delay module  126  also receives a feedback signal  72 - 1  through the feedback input  70  of the electronics module  120 . The delay module  126  uses the feedback signal  72 - 1  to tune the delay in the delayed antivoice signal  68 - 2  (step  150 ). The delay module  126  tunes the delay by using the feedback signal  72 - 1  to control a length of the delay in the delayed antivoice signal  68 - 2  by increasing or decreasing the length of the delay so that the antivoice output  42  generated later in the process by the suppression speaker  34  is opposite in phase to the voice  22 . The delay module  126  also uses the feedback signal  72 - 1  to filter out any antivoice output  42  received at the input microphone  30 . 
   In one arrangement, the delay is based on the distance from a location of the input microphone  30  and the location of the suppression speaker  34 . This delay is introduced to account for the faster speed of electronic processing in the electronics module  120  than the speed of sound as the voice  22  travels through the air over the distance from the input microphone  30  to the suppression speaker  34 . If the antivoice output  42  is provided without any delay, then the antivoice output  42  would not be out of phase with the voice  22  and would not effectively suppress the voice  22 . 
   In step  152 , the amplifier  128  then amplifies the delayed antivoice signal  68 - 2  to provide an amplified delayed antivoice signal  68 - 3  (step  152 ). The electronics module  120  outputs the amplified delayed antivoice signal  68 - 3  through the antivoice signal output  66  to provide the basis for the antivoice output  42 . 
     FIG. 7  shows, by way of example only, a block diagram providing additional detail for a delay module  160  suitable for use with the invention as one instance of the delay module  120  shown in  FIG. 5 . The delay module  160  includes circuitry for an analog-to-digital converter  162 , a delay controller  164 , a shift register  166 , and a digital-to-analog converter  168 . The delay module  160  is implemented, in one arrangement, as an ASIC. The delay module  160  provide electrical connections that provide electrical communication among the analog-to-digital converter  162 , the delay controller  164 , the shift register  166 , and the digital-to-analog converter  168 . The analog-to-digital converter  162  and digital-to-analog converter  168  are based on converter circuitry as is well known in the electronics art. The shift register  166  is based on shift register circuitry as is well known in the art. 
     FIG. 8  shows a flow diagram explaining the procedure  180  performed by the delay module  160  of  FIG. 7  when in operation. In step  182 , the delay controller  164  determines a delay to be added to the antivoice signal  68 - 1 . The delay controller  164  determines this delay based on a distance from a location of the input microphone  30  and the suppression speaker  34 , as described earlier for  FIG. 6 . The delay controller  164  then increases or decreases the amount of the delay an additional amount based on the feedback signal  72 . The analog-to-digital converter  162  converts the antivoice signal  68 - 1  to a digital signal (step  184 ). The shift register  166  shifts the digital signal the amount of delay determined by the delay controller  164  (step  186 ). The digital-to-analog converter  168  converts the digital signal to an analog signal to provide a analog delayed antivoice signal  68 - 2  (step  188 ). 
     FIG. 9  shows, by way of example only, a view of a mobile phone device  28  suitable for use with the audio privacy system  20  of  FIG. 1 . The mobile phone device  28  includes an input microphone  30 , an electronics module  32 , a suppression speaker  34 , a feedback microphone  74 , a personal speaker  36 , a phone controller  202 , a transmitter  206 , and a receiver  208 . The input microphone  30  outputs an analog voice signal  62 - 1  to the phone controller  202 . The phone controller  202  is a controller typical of the electronic circuitry used in a mobile phone, such as a cellular phone or satellite phone, that processes an incoming voice signal  62  when preparing a transmit signal  204  to be transmitted by a transmitter  206   
   In alternate arrangements, the electronics module  32  is incorporated into or combined with the phone controller  202 . For example, in one arrangement, the electronics module  32  and phone controller  202  are combined onto one integrated circuit. 
   The transmitter  206  is a transmitter as it typically used in mobile phones, as is well known in the art, to send an outgoing signal  207  to another mobile phone usually by a wireless radio approach. The receiver  208  is a receiver as is typically used in mobile phones, as is well known in the art, to receive an incoming signal  210 , process the incoming signal  210 , and send an output signal  212  to the personal speaker  36  so that the user  24  hears the output signal  212  from the personal speaker  36 . In one arrangement, the volume of the output signal  212  to the personal speaker  36  is increased slightly in comparison to conventional models to make up for a loss in fidelity of the voice  22  in the user&#39;s  24  other ear due to the antivoice output  42 . The phone controller  202  also provides a duplicate signal  214  which is a duplicate of the voice signal  62 - 1 . The phone controller  202  outputs the duplicate signal  214  to the personal speaker  36  so that the user  24  hears a representation of his or her own voice in the personal speaker  36  while he or she is talking into the input microphone  30 . 
   In one arrangement, the phone controller  202  provides voice processing circuitry that produces a digitized voice signal  62 - 2  based on the voice signal  62 - 1 . The electronics module  32  receives the digitized voice signal  62 - 2  and generates an antivoice signal  68  based on the digitized voice signal  62 - 2 . The electronics module  32  outputs the antivoice signal  68  to the suppression speaker  34 . In one arrangement of the invention, the electronics module  32  includes a digital-to-analog converter (see  FIG. 7 ) that converts a digitized signal based on the digitized voice signal  62 - 2  to an analog antivoice signal  68  suitable for use by the suppression speaker  34 . In another arrangement, the electronics module  32  also receives a feedback signal  72 - 3  from a feedback microphone  74 . The electronics module  32  uses the feedback signal  72 - 3  to modify the antivoice signal  68 . 
     FIG. 10  shows, by way of example only, an overhead view of a mobile phone device  28 , including a plurality of voice suppression speakers,  34 - 1 ,  34 - 2 ,  34 - 3 . The mobile phone device  28  includes an input microphone  30  for receiving the voice input  38  from the user  24 , an electronics module  32 , and a plurality of voice suppression speakers,  34 - 1 ,  34 - 2 ,  34 - 3  generating a plurality of antivoice outputs  42 - 1 ,  42 - 2 ,  42 - 3  forming a plurality of voice suppression zones  46 - 1 ,  46 - 2 ,  46 - 3 . The antivoice outputs  42 - 1 ,  42 - 2 ,  42 - 3  combine with the voice  22  to form the suppressed voice outputs  44 - 1 ,  44 - 2 ,  44 - 3 . The unintended listener  26 - 2  cannot understand or has difficulty understanding the suppressed voice output  44 - 2  in the voice suppression zone  46 - 2  that encompasses the unintended listener  26 - 2 . The other voice suppression zones  46 - 1  and  46 - 3  may encompass other unintended listeners  26 - 1  and  26 - 3 . In addition, if the unintended listener  26  moves out of the voice suppression zone  46 - 2 , he or she is likely to encounter another one of the multiple voice suppression zones  46 - 1 ,  46 - 2 ,  46 - 3 . For example, voice suppression zone  46 - 1  encompasses unintended listener  26 - 1  and voice suppression zone  46 - 3  encompasses unintended listener  26 - 3 . Also, at a sufficient distance, or if two or more of the suppression speakers  34 - 1 ,  34 - 2 ,  34 - 3  are located near each other, then a merged voice suppression zone  46 - 4  is produced such as the merger of voice suppression zones  46 - 2  and  46 - 3  for unintended listener  26 - 4 . 
   The invention is not limited to three suppression speakers  34 - 1 ,  34 - 2 ,  34 - 3  located at the front or the sides of the user  24  of the mobile phone  28 , as shown in  FIG. 10 . In another arrangement, the mobile phone  28  includes a different number of suppression speakers.  34 , which are placed on any available position on the mobile phone  28  not facing toward the user  24 . Thus, in alternate arrangements, the suppression speakers  34  can be placed in other locations, such as directed rearward, or in several locations, to provide a circle of 360 degree coverage around the user  24  for the voice suppression zones  46 . In another arrangement, the suppression speakers  34  are in electrical communication with the mobile phone  28  using a radio or other link to one or more suppression speakers  34 , are located at a distance, such as several feet, from the mobile phone  28 . 
   In a further arrangement of the invention, the suppression speakers  34 - 1 ,  34 - 2 ,  34 - 3  are capable of being selectively enabled or disabled and one or more of the suppression speakers  34 - 1 ,  34 - 2 ,  34 - 3  may be selected to provide the antivoice output  42 - 1 ,  42 - 2 ,  42 - 3 . In one arrangement, the user  24  sees an unintended listener  26 - 2  in front of her and selects the voice suppression speaker  34 - 2  to be enabled. Typically, the user  24  makes the selection of the voice suppression speaker  34 - 2  through a switch, button, or voice command that provides a selection signal to the electronics module directing the electronics module to enable the antivoice output  34 - 2  for only that suppression speaker  34 - 2 , while the other speakers  34 - 1  and  34 - 3  remain silent. This selection approach provides a benefit in that power is conserved by not powering all of the suppression speakers  34 - 1 ,  34 - 2 ,  34 - 3 , thus extending battery life. 
   Another arrangement of the mobile phone  28  includes one or more direction detectors that the electronics module  32  uses to detect the directions of one or more unintended listeners  26 . The direction detector uses radar, sonar, infrared radiation detection, or some other method to determine the direction of each unintended listener  26 , as is known in the respective arts. The electronics module  32  then selectively enables one or more of the suppression speakers  34 - 1 ,  34 - 2 ,  34 - 3  in order to encompass the detected unintended listener  26  in one of the voice suppression zones  46 - 1 ,  46 - 2 ,  46 - 3 . If the direction detectors no longer detect an unintended listener  26  after he or she leaves a voice suppression zone  46 - 1 ,  46 - 2  or  46 - 3 , then the electronics module  32  selectively disables whichever voice suppression zone  46 - 1 ,  46 - 2 ,  46 - 3  that the electronics module  32  had previously enabled. 
   In an alternate arrangement, the mobile phone  28  includes one or more direction detectors and a movable suppression speaker  34  capable of being oriented in different directions by signals sent to the suppression speaker  34  from the electronics module  32 . For example, in one arrangement, the suppression speaker  34  includes an electric motor that pivots the suppression speaker  34  so that it faces in different directions in response to a command from the user  24  or the electronics module  32 . 
   The above-described features of the invention are well suited for use with devices manufactured by Cisco Systems, Inc. of San Jose, Calif. 
   While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. 
   For example, it should be understood that the audio electronic device  60  is not limited to a mobile phone  28 , such as a cellular phone or satellite phone. It should be understood that audio electronic device  60  can be any electronic device receiving audio input, such as a hands-free headset, recording device, computer, or other devices. The audio electronic device  60  can be any type of phone device that includes a transmitter  206  that generates a outgoing signal  207  that is capable of being received by another audio electronics device  60 , a receiver  208  that is capable of receiving an incoming signal  210  from the other audio electronics device  60 , and a personal speaker  36 . The transmitter  206  can be a radio-based transmitter, such as in a cellular phone, cordless phone, or a satellite phone, or a transmitter  206  in a desk telephone that sends the outgoing signal  207  over a phone wire connected to a public telephone system. The receiver  208  can be a radio-based receiver or the receiver  208  in a desk telephone. In addition, the transmitter  206  of one audio electronic device  60  and the receiver  208  of another audio electronic device can communicate by infrared radiation, laser radiation, or radiation based on other parts of the electromagnetic spectrum. The audio electronic device  60  can be a computer with an input microphone  30 , such as a laptop computer that a user  24  speaks into to communicate with the computer using speech recognition software. 
   It should be understood that the boundaries  48  of the voice suppression zone  46  shown in  FIG. 1  are shown by way of example only. The suppression speakers  34  can be of different types that can produce voice suppression zones  46  of different sizes with different boundaries  48  than those shown in  FIG. 1 , depending on the type of suppression speaker  34 . 
   The invention is not limited to voice input  38  based on a user  24  speaking an intelligible message. It should be understood that the voice input  38  to be suppressed can include other sounds than intelligible speech. Also, the voice input  38  can include music sung or played by an instrument into the input microphone  30 . For example, the voice input  38  can include a tape recording or music from a radio played into the input microphone  30 . 
   The invention does not require the voice input  38  to be provided by a person. It should be understood that the voice input  38  can be any voice  22  or audio input into the input microphone  30 . The voice input  38  can be noise or sound provided by another living thing, such as an animal. The voice input  38  can be an intelligible message, a sound, or a noise made into the input microphone  30  by another device, such as a computer or a robot having a speaker of its own producing a voice input  38  for the input microphone  30 . 
   It should be understood that all or part of the electronics module  32  can also be implemented as software instructions or program that executes on a general-purpose processor, such as an Intel® Pentium® microprocessor. For example, in one arrangement, the audio electronic device  60  is part of a general-purpose computer and the electronics module  32  is implemented as a software program or application that can be installed on the general-purpose computer from a computer program product. For example, a laptop computer can have an audio electronics device  60  incorporated into the laptop, in which case the electronics module  32  is implemented as a software module executing on the laptop computer. 
   It should be understood that the functional blocks shown in  FIGS. 2 ,  5 ,  7 , and  9  are not definitive and not meant to be limiting in any way. For example, it should be understood that the delay module  160  of  FIG. 6  can be implemented as one circuit or integrated circuit chip. Alternatively, one or more parts of the delay module  160 , such as the analog-to-digital converter  162 , the delay controller  164 , the shift register  166 , and the digital-to-analog converter  168 , can be implemented as one or more circuits or one or more integrated chips. It should also be understood that various modifications can be made to the circuitry of the invention. For example, the circuitry for generating the delay can be placed before the circuitry for generating the antivoice signal  68 . In other words, the voice signal  62  is first delayed, and then a delayed voice signal is inverted to generate the antivoice signal  68 . 
   It should be understood that the invention is not limited to a single input microphone  30  or a single feedback microphone  74 , as shown in  FIG. 2 . Rather, other arrangements of the invention can include multiple input microphones  30  used with a mobile phone  28  or other audio electronic device  60 . In one arrangement, the invention includes multiple input microphones  30  at different positions on the mobile phone  28 , each microphone  30  oriented to receive the voice  22  of the user  24 . In a further arrangement, the mobile phone  28  includes multiple input microphones  30  used with multiple suppression speakers  34 . Each suppression speaker  34  is associated with an input microphone  30 . Typically, each suppression speaker  34  is associated with the input microphone  30  that is closest to it. The electronics module  32  determines the delay for each suppression speaker  34  separately and determines a separate antivoice signal  68  for each suppression speaker  34 . The delay for the antivoice signal  68  for a particular suppression speaker  34  is based on the distance from that suppression speaker  34  to its associated input microphone  30 . 
   In one arrangement, the invention includes multiple input microphones  30  to detect the orientation of the voice  22  relative to the position of the mobile phone  28 . The invention then uses this information on the orientation of the voice  22  to more effectively output the antivoice output  42  into a voice suppression zone  46 . For example, the orientation of one or more suppression speakers  34  may be changed in response to the orientation of the voice  22  to change the direction of the antivoice output  42 . 
   In a further arrangement, the invention includes multiple feedback microphones  74 . For example, a feedback microphone  74  is associated with each suppression speaker  34 . The electronics module  32  uses the feedback signal  72  associated with a particular suppression speaker  34  in determining the delay in the antivoice signal  68  for that suppression speaker  34 .